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- Fertilization system and soil-climatic conditions
- Zonal peculiarities of fertilizer systems
- Fertilizer efficiency depending on agrotechnical factors
- Efficiency depending on the amount and quality of fertilizer
- Methods for determining fertilizer doses
- Methods and timing of fertilizer application (Русская версия)
- Fertilization system and soil-climatic conditions
- Zonal peculiarities of fertilizer systems
- Fertilizer efficiency depending on agrotechnical factors
- Efficiency depending on the amount and quality of fertilizer
- Methods for determining fertilizer doses
- Methods and timing of fertilizer application (Русская версия)
Critical and maximum period
Critical period is the period of plant vegetation when the lack of any element has the most negative effect on growth, and the subsequent optimization of nutrition does not fully correct this effect. The critical period of nitrogen and phosphorus nutrition for most crops falls within 10-15 days after sprouting. Lack of potassium in the first phases of plant development reduces yields, but improving potassium nutrition in subsequent phases allows to correct the negative impact.
Deficiencies in nitrogen and phosphorus are often evident in early spring, when low soil temperatures reduce the activity of microorganisms that mineralize soil organic matter.
The maximum period is the period in plant nutrition at which the average daily intake of nutrients is maximal. Most often, the maximum falls on the period of the highest growth of dry matter.
Fertilizer application methods
There are three basic methods of fertilizer application:
- pre-sowing (row), or pre-planting;
- post-sowing (top dressing).
The basis for calculating the rates of fertilizers for crops are the physiological needs of plants in elements of nutrition. In the absorption of nutrients are distinguished critical and maximum periods.
Creating an optimal regime of plant nutrition during the growing season, taking into account the implementation of the potential productivity of plants in terms of quantity and quality of yield is possible with a rational combination of all methods of fertilization.
Under conditions of low moisture and arid climate the splitting of the total dose of the main fertilizer and top dressing, most often, agronomically and economically unreasonable.
According to the method of fertilizer incorporation, a distinction is made:
- local – in rows, sockets or wells;
For soluble and soil-absorbed fertilizers, local and local-tapered are effective methods of application. The main fertilizer for crops with a row seeding method can be applied by local-taper method with special devices for plows and cultivators-ploughs. With local application the nutrients are less fixed by the soil and are more accessible to the plants, increasing their utilization factor.
Table. Influence of fertilizer application methods on consumption of main nutrition elements by spring wheat, in % of absolute dry matter weight (according to Y.V. Evtefeev, 1971)
The uptake of nutrients by spring wheat increases with the local-tape method of application of the main fertilizer compared with the spreading method. At the same time grain yield of wheat increases by 0.05-0.11 t/ha.
Table. Effect of methods of fertilizer application on the yield of spring wheat, 1969-1970. (according to Y.V. Evtefeev, 1971)
|Control (plowing land without fertilizer)|
|Р10 in the rows when sowing|
|N60P60K60 in a spreading method under the autumn plowing|
|N60P60K60 locally-tapered method under the autumn plowing|
|N60P60K60 locally-tapered method under the autumn plowing + P10 in the rows when sowing|
Organic fertilizers are embedded deeper into the soil, especially on light soils. In humid climates, shallow incorporation is preferred on heavy soils to accelerate mineralization. Mineral fertilizers, especially nitrogen fertilizers, are applied together with organic fertilizers to reduce nitrogen consumption from the soil humus.
Main (pre-sowing) fertilizer
The main, or pre-sowing, fertilizer is designed to meet plant nutrient needs after seedlings until the end of the growing season. For most crops under conditions of sufficient moisture or irrigated agriculture the main fertilizer accounts for 60-90% of the total dose, under conditions of insufficient moisture – 90-100%.
The main organic and phosphorus-potassium fertilizer is usually carried out in autumn, nitrogen – in spring under the pre-sowing tillage in areas of sufficient moisture or with others – in autumn under the main tillage in areas of insufficient moisture with embedding implements scattered or locally. The effectiveness of deep embedding of fertilizers before sowing increases with increasing soil moisture deficit and aridity of the climate.
The main (pre-sowing) fertilizer is embedded with the plow during autumn plowing. Before sowing of any crop and during the growing season plants must be provided with a certain amount of nutrients in each period. This is achieved by mobilizing the natural fertility of the soil, or by fertilizing.
The correct ratio of nutrients is important, and its violation makes it difficult for the plant to use them. For example, the lack of phosphorus causes excessive accumulation of nitrate nitrogen in plants. The combined application of phosphorous and nitrogen fertilizers normalizes the nitrate nitrogen content in plants. The optimal ratio of nutrients affects their arrival in the plant, the direction of the synthesis of organic compounds, the growth and formation of yield and product quality.
Even J. Liebich noted that fertilizers work most favorably if they are used to establish the correct ratio of nutrients in the soil. This was also pointed out by D.N. Pryanishnikov, who wrote that the effect of phosphorus fertilizers depends on the provision of plants with other elements, primarily nitrogen.
Before sowing, most of the total dose of fertilizer provided for the crop is usually applied.
Timing of the main fertilizer and method of embedding are determined by climatic conditions of the zone, the properties of soil and fertilizers, and biological characteristics of crops. For example, in the forest-steppe of European Russia, where the best moisture conditions, 60-70% of the total dose of fertilizers is used in the main application, the rest is applied in rows at sowing and in top dressing. For row crops in this zone, deep autumn plowing of fertilizers has an advantage over spring plowing during the cultivation of the autumn tillage.
In the zone of sod-podzolic soils with sufficient moisture and irrigation, the fertilization system of crops consists of three methods: the main, pre-sowing and top dressing. In this zone, about 50% of the total rate is applied before sowing.
In the zone of sufficient moisture, on heavy waterlogged soils, re-tillage of autumn plowing is usually carried out in spring. This is done when preparing the soil for row crops with a well-developed root system. In this case, the fertilizer is applied in spring when plowing the tilled soil in autumn. In these conditions, the high efficiency of fertilizers is observed when they are applied in the spring before sowing with subsequent embedding by the cultivator.
Cultivation of fertilizers applied before sowing is also acceptable in the forest-steppe for winter cereals. Here, during harvesting of late fallow-occupying crops and when there is a lack of moisture to avoid drying out the soil is limited to surface pre-sowing tillage, such as discing, cultivation, deep discing. In this case, the fertilizer intended for the main reception, applied after harvesting of the winter predecessors.
The choice of optimal timing of application is determined by the properties of the soil, especially granulometric composition. Thus, on light soils and with sufficient moisture most of the nutrients, especially nitrogen, will migrate along the soil profile outside the root layer. Therefore, embedding, especially nitrogen fertilizers, is carried out in spring.
In determining the timing and method of application of fertilizers are also based on the properties of the fertilizer itself. Phosphate fertilizers are well absorbed by the soil at the point of application, phosphorus little migrates along the soil profile, quickly fixed by the chemical absorption, especially on soils with high absorption capacity and the degree of saturation of the bases. Danger of phosphorus leaching on such soils is almost absent. Potassium is well kept by soil, except for light soils with low absorption capacity. Nitrogen fertilizers are the most mobile.
Almost all agricultural regions of Russia noted the effect of phosphorus, and often potassium fertilizers with the fall with the subsequent incorporation of the plow when plowing the soil tilled in autumn. Nitrogen fertilizers in areas of sufficient moisture, especially on light soils, is made in spring with subsequent incorporation of the plow when plowing the soil tilled in autumn, or cultivator. For winter cereals, a portion of nitrogen fertilizer is applied before sowing to create optimal conditions for development in the fall.
When applying nitrogen fertilizers, take into account the characteristics of crops. For example, under row crops with a well-developed root system, the best effect is achieved by deep embedding the fertilizer. Also take into account the form of fertilizers. Thus, ammonia forms of nitrogen fertilizer fertilizers made and from autumn, as ammonium is well retained by soil. Nitrate nitrogen is not adsorbed by the soil, so it moves with the soil solution. Therefore, the application of nitrate forms of nitrogen fertilizer in autumn with sufficient moisture, especially on light soils leads to significant losses of nitrogen.
Potassium fertilizers often contain a large amount of ballast elements, so the introduction of chlorine fertilizers under the culture, negatively reacting to chlorine, leads to a decrease in yield and quality problems. If it is necessary to apply chlorine-containing potash fertilizers, they are applied in autumn under autumn plowing. In this case, chlorine poorly adsorbed by the soil is washed into the underlying layers and does not have a negative effect on the yield. It is especially inadmissible to apply chloride-containing potash fertilizers to chlorophobic crops during the growing season.
Local application of the main fertilizer – by tapes, cords on the bottom of the furrow – is effective. With these methods fertilizers are not mixed with soil, are closer to the feeding part of the root system and are used by plants more effectively. Increased efficiency from the tape application of fertilizers associated with the localization of phosphate fertilizers. With this method phosphate fertilizers have less contact with the soil, resulting in water-soluble calcium phosphates are less converted to hard-soluble forms and are more fully assimilated by plants.
Local application of the main mineral fertilizer has a positive effect on the growth and physiological state of leaves, causes increased water retention capacity, increases the productivity of photosynthesis.
The advantage of the local method of fertilizer application is a higher coefficient of fertilizer use compared to the spreading method. The fertilizer dose with local application can be reduced by 30-50% compared to the spreading method.
More promising is a two-layer local fertilizer application before sowing crops.
Two-layer local application provides an intensive supply of nutrients during the entire growing season, which increases the effectiveness of this technique before both scattered and local application of fertilizers in one layer.
Table. Effectiveness of two-layer local application of mineral fertilizers
Spreading is less effective, but has been used in Russia for decades. The basic fertilizer is applied by scattered mix seeders, spreaders of mineral fertilizers and aerial spreaders.
Depending on natural and economic conditions, the main (pre-sowing) fertilizer is applied annually to each crop, sometimes, for example, under spring cereals with undersowing of perennial grasses – immediately under the cover crops contribute a total dose of phosphorus, sometimes combined with potassium, for her and the cultivated grasses of one or two years. This method is called a periodic, or reserve, application. This technique includes phosphoritization of soils, application of organic fertilizers, or special application to one annual crop of a dose calculated for three crops at once.
Numerous experiments comparing the equivalent doses in different soil and climatic zones show that the periodic (once every 3 years) application of phosphate fertilizers for annual crops is usually more effective than the annual. Under perennial forage and fruit crops, this method is even more effective.
When making the main fertilizer in the calculated rates for cereal crops efficiency row method of application is reduced. For example, rowwise application of granulated superphosphate at a dose of 10 kg/ha against the background of the main fertilizer N60P60K60 did not provide a significant increase on the leached chernozem of the experimental field of the Altai Agrarian University.
Pre-sowing (row fertilization) or pre-planting fertilizer
The pre-sowing (row fertilizer) or pre-planting fertilizer is designed to meet plant nutrient requirements during the period from germination to the appearance of full seedlings. As a rule, it does not exceed 2-10% of the total dose. Water-soluble phosphorus, less often phosphorus-nitrogen or phosphorus-nitrogen-potassium fertilizers are used more often.
It is a local most effective way of application simultaneously with the sowing of seeds in the form of a string (strip) under them or on the side at a distance of 2-3 cm. It is also called the first mandatory method of fertilizing under all crops in all soil and climate zones. Doses of fertilizers in any method of application, especially in row application, should be optimal, since the increased concentration of soil solution and osmotic pressure can lead to thinning, and in excess to the death of crops and reduce overall productivity.
Table. Optimal and maximum doses (kg/ha a.s.) and composition of pre-sowing fertilizer of main crops in the Non-Black Soil zone of RussiaYagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
|Beets (all types)|
The main task of pre-sowing fertilization is to improve root nutrition in the first period of plant life. This method was developed in Russia by A.E. Zaykevich in 1880. For the first time fertilizers were introduced into the rows during the cultivation of sugar beets; later superphosphate was used for sowing cereals and other crops. Currently, there are special combined seeders for simultaneous sowing of seeds and fertilizer. In this method, fertilizer can be applied directly into the wells when planting potatoes or seedlings. This method uses small doses of fertiliser.
When fertilising with a combination drill, the seeds are separated from the fertiliser by a layer of soil. During germination, seeds and young seedlings, which are very sensitive to high salt concentrations, do not come into contact with fertiliser. This sensitivity is usually higher in small-seeded plants.
Providing plants with nutrients during the first period of life is important for later development. As young plants are particularly sensitive to nutrient deficiencies. Row or nest fertilization during sowing creates favorable nutritional conditions for the young plants, so they grow faster and more easily tolerate adverse conditions.
Favorable nutritional conditions at the beginning of growth allow young plants in a shorter time to develop a strong root system, which makes it possible to better use the nutrients of the soil and the main fertilizer in the future.
There is an increased need of plants for phosphorus fertilizers in the early period of vegetation, which is associated with the participation of phosphorus in the processes of synthesis and hydrolysis of carbohydrates. The breakdown of stored polysaccharides into monosaccharides is due to phosphorolysis. Phosphorous fertilizers introduced into rows with seeds contribute to economical expenditure of plastic substances of seeds due to slower hydrolysis of starch and reduced activity of oxidative enzymes. When assimilating apparatus appears in plants, phosphorus leads to increased hydrolysis of starch of seed, which is spent on growth processes more effectively.
Under the influence of nitrogen, starch hydrolysis, respiration rate and activity of oxidative enzymes increase, which leads to premature consumption of plastic substances of the seed. To eliminate the negative effect of nitrogen on the transformation of substances in the seed before the formation of photosynthetic apparatus, some isolation of fertilizer nitrogen from the seed is necessary. Count on the sustained positive effect of row application of nitrogen fertilizers close to the seeds can be expected only for non-acidic soils saturated with calcium, sufficiently supplied with phosphorus available to the plant and in need of nitrogen, as well as for plants with seeds with large reserves of carbohydrates (wheat, oats, barley).
Nitrogen application in nutrient solution significantly increases the phosphorus content in nitrogen fractions of organophosphorus compounds, primarily in the nucleoprotein fraction – substances that play a role in the differentiation of meristematic tissues, that is, the ways of effective fertilizer impact on the form-forming processes in plants.
Violation of the optimal ratio of nitrogen and phosphorus at the beginning of growth leads to disruption of the synthesis of amino acids, nucleoproteins, which determine the initial growth of plants. Therefore, on soils poor in nitrogen, it is proposed to apply small doses of nitrogen at sowing in conjunction with phosphorus fertilizer. On soils with low fertility and low nitrogen content it is recommended to make during sowing in addition to phosphorus-potassium fertilizer and nitrogen fertilizer in the dosage of 5-10 kg/ha of nitrogen.
As pre-sowing fertilizer is recommended ammophos, nitrophoska. High efficiency of pre-sowing fertilizer is confirmed by numerous data obtained in different regions of Russia and abroad. There is also a high payback of fertilizers made in the rows during sowing.
The composition of fertilizers applied by row and their effectiveness is determined by the biological characteristics of crops, agrochemical properties and soil fertility, the properties and forms of fertilizers, prefertilization of fields. There is a high effect of granulated superphosphate introduced into the rows during sowing. This is due to the increased need of crops in phosphorus at the beginning of the growing season and, thanks to granulation and topical application, the processes of retrogradation of phosphoric acid superphosphate proceeds slower due to less contact with the soil absorbing complex. Due to the water-soluble form of P2O5 in superphosphate and its proximity to the root system, it is actively used by plants. The utilization rate of P2O5 superphosphate at local application is 2-3 times higher than at scattered application. Phosphorus improves the development of the root system, thereby increasing the resistance of plants to drought and other adverse conditions.
Table. Comparative effectiveness of granulated superphosphate when applied in rows and scattered under the cultivatorAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov, etc.; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
Pre-sowing (row fertilizer) fertilizer during sowing of cereals, in the wells (sockets) during planting of vegetable crops is applied locally, which increases the rate of use of nutrients. Doses of row fertilizer – 5-10 kg of nitrogen, phosphorus and potassium per 1 ha.
With row fertilization the most effective phosphate fertilizers – granulated superphosphate, ammophos. On soils with a low content of available phosphorus row fertilizer superphosphate is carried out at a dose of 10 kg a.s./ha, which provides an increase in grain yield of spring wheat by 0.26 t / ha.
Post-sowing fertilizer (top dressing)
Post-sowing fertilization, or top dressing, is used to obtain a high yield and improve its quality. The technique allows to strengthen plant nutrition in certain periods of development, complements or improves the effect of the main fertilizer. The combination of these methods can provide optimal nutrition of plants during the growing season. Fertilizing accounts for 20-30% of the total dose.
Fertilizing is carried out on the surface, embedded in the soil, scattered and local, dry and liquid fertilizers, root and foliar. Fertilizing with nitrogen fertilizers is necessary for winter cereals and perennial grasses.
Fertilizing is especially important on soils of light granulometric composition, in areas with sufficient moisture. Thus, when cultivating winter cereals and row crops on sod-podzolic soil and in the northern forest-steppe, top dressing on sandy loam soils with low absorption capacity, which require fractional fertilizer application, is effective. Application of the full rate of fertilizers in these areas in the main reception leads to large losses of nutrients by leaching from the root layer, reducing the effectiveness of fertilizers and increasing the negative impact on the environment.
Sometimes there are conditions for feeding row crops in areas with insufficient moisture: with sufficient soil moisture during the spring-summer vegetation and insufficient fertilizer application in the main reception. Fertilizing can be carried out superficially on the soil, in the soil during the vegetation of plants, and foliar, in which the fertilizer solution is applied directly to the vegetative parts of plants.
Surface dressing is used mainly for crops of continuous sowing. For example, an effective technique for winter wheat is early spring top dressing. Fertilizers are applied by fertilizer machines – by ground method or specially adapted for this purpose planes and helicopters.
Fertilization of row crops such as sugar beet, cotton, corn and potatoes is widely used. Fertilizers are applied by plant fertilizers or special devices for inter-row cultivation tools.
On the efficiency of top dressing affect natural conditions, moisture during the growing season, soil fertility and granulometric composition, biological characteristics of crops, properties of fertilizers, conditions of agrotechnics.
The efficiency of fertilizing depends on the type and forms of fertilizers. Phosphate fertilizers full rate is often made in the main reception before sowing, which as a result of chemical fixation, almost not lost from the soil. Also there is no significant loss of potassium when using potassium fertilizers in the main application, with the exception of light soils and sufficient moisture. Therefore, most of the dose of these fertilizers is applied before sowing.
The most mobile – nitrogen fertilizers, as all forms of nitrogen in good moisture and optimal temperature as a result of nitrification converted to nitrate form, which is not bound to the soil and migrates through the profile with moisture. Therefore, the full application of nitrogen fertilizer before sowing in winter can lead to significant losses of nitrogen with melt water.
Feeding of winter cereals and row crops is primarily carried out with nitrogen fertilizers in nitrate forms, which quickly migrate with soil moisture and reach the active absorbing part of the root system.
Many crops by their biological peculiarities cannot tolerate high concentration of salts, especially at the beginning of vegetation. Therefore, the application of increased doses of mineral fertilizers before sowing can have a negative impact on initial development, and in subsequent periods, increased amounts of nutrients are required. Therefore, feeding allows you to regulate plant nutrition by growth phases.
The effect of feeding is determined by the application of a set of agricultural techniques. Thus, under irrigation of cereal crops, top dressing is a method of increasing yield and improving grain quality. In areas of old irrigated agriculture when cultivating cotton, application of full dose of nitrogen before sowing always leads to lower results than application in several methods. This is explained by the fact that during irrigation nitrogen fertilizers migrate with irrigation water along the soil profile, and in spring with rising water currents they rise to the surface and concentrate in the upper layers, where there is almost no root system.
Late foliar top dressing of crops is carried out with fertilizer solutions. Late foliar fertilization has the greatest practical importance for increasing grain protein content and improving other indicators of wheat quality.
The best fertilizer for foliar feeding of wheat is urea, which gets on the leaf surface and is directly used by wheat for protein synthesis, which explains the positive effect of foliar feeding of wheat with urea during spike emergence and flowering. At the beginning of milk ripeness grain contains up to 40-50% of all the nitrogen at full grain ripeness, at the beginning of wax ripeness – up to 80%, the rest of the nitrogen goes to the grain at wax ripeness. Application of nitrogen fertilizers in the period of milk ripening increases the nitrogen content in grain and increases the yield.
The positive effect of urea is explained by the fact that it is a source of nitrogen nutrition and physiologically active substance, activates the processes of nitrogen metabolism, in particular the formation of sulfhydryl groups of amino acids methionine, cysteine and tripeptide glutathione. Amino acids containing SH-groups are involved in the processes of metabolism, growth and the formation of reproductive organs. Urea also affects the water regime of plants: late nitrogen fertilization increases hydration of colloids by increasing the total amount of nitrogen, water-soluble and non-extractable proteins. The amount of firmly bound water also increases and the water-holding capacity of leaves increases.
The mechanism of mineral uptake by leaves is similar to that of roots. The first step in the absorption of ions from the solution is exchange adsorption – the process proceeds very quickly on the absorbing surface. In roots and leaves, the absorption of salts from a solution depends on the pH of the medium, solution concentration, salt composition, duration of contact of the solution with the absorbing surface, and the age of the absorbing organ.
In a plant, there is a relationship between all vital processes, including root and foliar nutrition. Therefore, foliar fertilization increases, under certain conditions, the efficiency of fertilizers applied to the soil and the efficiency of soil fertility use. The link in this case is photosynthesis.
A foliar top dressing, increasing the intensity of photosynthesis, provides an influx of organic matter and energy material to the roots, which leads to increased respiration, rapid growth of roots, increasing their absorptive surface, which in turn leads to increased absorption of minerals. On the other hand, inflow of nutrients to leaves results in binding and retention of photosynthesis products at the place of their formation, which should have a negative effect on root activity and lead to a decrease in yield. Negative effect of foliar fertilizer on plant productivity is usually observed when it is used in the first half of the growing season, when synthetic processes prevail. A positive effect, especially on the quality of yield, appears when foliar dressing is carried out after flowering, in the period of predominance of hydrolysis processes.
The presence of an increased amount of sugars in plants after flowering allows more intensive absorption of nitrogen applied to the leaves, without compromising nitrogen absorption by the roots. Considering that by this period the absorptive activity of the roots decreases, the competition for sugars as a product of photosynthesis between the leaves and the roots is weaker. Nitrogen that entered through the leaves is well distributed throughout the plant. Normal distribution of phosphorus between the parts of the plant is possible when it comes through the roots.
Nitrogen top dressing of wheat during spike formation and flowering is an additional application in the fertilization system, but does not exclude the main fertilization, late autumn and early spring fertilization.
Yield increase from foliar fertilizing of winter wheat with urea occurs due to increase of absolute grain weight. foliar feeding provides an increase in grain yield by 150-300 kg/ha. Foliar top dressing of wheat with urea at the phases of spike formation, flowering and the beginning of milk ripening increases the protein content of grain by 1.5-2%. When foliar top dressing of sugar beet before harvesting with phosphorus-potassium fertilizer the yield increased by 10%, sugar content – by 1%.
Foliar top dressing of winter wheat with urea solution is carried out with the help of aircraft. The concentration of the solution in this case can be brought to 30%. Superphosphate solution in a 1:4 ratio, with a concentration of P2O5 about 5%, is prepared for 1-2 days because of the slow dissolution, with periodic shaking. Potassium salts are well soluble in water, so their solutions can be prepared the day before spraying. The concentration of potassium chloride solution is 3%, or 25-30 kg of potassium chloride per 800 liters of water. When spraying from an airplane, the flight altitude should be about 5 m. The AN-2 aircraft capacity is 8-10 ha per flying hour or 50-70 ha per working day; the solution consumption is 800 l/ha.
Post-sowing fertilization is effective in conditions:
- Early spring feeding of winter crops and perennial grasses with nitrogen fertilizers at a dose of 30 kg a.s./ha. For top dressing ammonium nitrate, ammonium sulfate, urea are used.
- Row crops top dressing with nitrogen and potassium fertilizers on light soils in the conditions of sufficient moisture and irrigation. Dose of fertilizers in the top dressing N – 30-40 kg/ha, K2O – 30 kg/ha.
- At high calculated rates of fertilizers for crops sensitive to high concentrations of salts in the soil solution.
- On long-term cultivated hayfields and pastures. When high estimated rates of fertilizers and applying them in one go increases the content of nitrogen and potassium in the pasture forage, which leads to animal disease. Therefore, the calculated rate is divided into several doses and applied fractionally after each mowing or grazing cycle.
- Nitrogen foliar fertilizing of winter and spring wheat according to the results of plant diagnostics during earing – milky ripeness to increase protein content and gluten quality in grain.
Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. – Moscow: Kolos, 2002. – 584 p.: ill.
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.
Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.
All methods of determining fertilizer doses are based on data from long-term or episodic field and production experiments, and differ in the completeness and accuracy of reflecting the patterns of relationships of plants, soils and fertilizers.
All existing methods and their modifications for determining fertilizer doses can be divided into:
- methods of generalizing the results of experiments with empirical fertilizer doses;
- methods of generalizing the results of experiments with the help of balances of nutrients.
All of the above methods of optimizing fertilizer doses can fairly objectively predict the value of crop yields. But despite this, they require improvement in terms of a comprehensive approach, taking into account the conditions of growing crops and economic payback of fertilizers.
Methods based on generalization of data with empirical fertilizer doses
Generalization carried out under the methodological guidance of the Geographical Network of experiments All-Russian Institute of Fertilizers and Agrochemistry (VIUA) in all soil and climate zones with different crops, the results of field experiments allowed to determine the effectiveness of certain types of fertilizers on different types of soils and doses of organic and mineral fertilizers for major crops on different types and subtypes of soils. Subsequently, differentiation of doses within the varieties (subtypes) of soils, taking into account the provision of nutrients to preceding crops and varietal characteristics was carried out.
Based on the generalized results of the experiments doses, optimum timing and methods of fertilizing before sowing, during sowing and after sowing for the main crops in all soil and climatic zones were also developed.
According to the Geographic Network of Experiments VIUA and agrochemical service CINAO, for the main soil and climatic zones of Russia on the prevailing types of soils with an average content of mobile phosphorus and exchangeable potassium recommended optimum doses of macrofertilizers for major crops, as well as doses and methods of making microfertilizers.
Table. Optimal doses of mineral fertilizers (kg/ha) for main crops (generalization by Litvak, 1990)
|Winter wheat||Non-Black Earth|
|Silage crops||Non-Black Earth|
|Sugar beet||Non-Black Earth|
Table. Doses and methods of microfertilizer application for major crops (summarized by Litvak, 1990)
|Beets (all types)|
|Vegetables and potatoes|
Regional research institutions offer more specific recommendations for crops, types, subtypes and varieties of soils, indicating the levels of planned yields, cultivation of soils and in combination with doses of organic fertilizers.
In each set of specific natural and economic conditions of territories based on the results of at least 7-10 reproducible experiments with one crop or variety the regional institutions of the Geographic Network of Experiments and Agrochemistry Service determine the quantitative indicators of fertilizer efficiency:
- yield increase from the optimal dose;
- element removal per unit of main and by-products and coefficients of soil element and fertilizer use;
- coefficients of return or intensity of element balance;
- correction coefficients to doses depending on soil class;
- rates of mineral fertilizer inputs to produce a unit of increase and yield as a whole;
- optimum levels of nutrients in soil;
- standard costs of fertilizers per unit of change in the content of mobile forms of elements in the soil;
- key indicators of product quality;
- economic indicators of fertilizer efficiency;
- mathematical models characterizing the relationship between crop productivity, soil fertility, fertilizer doses, weather and agrotechnical factors;
- levels of environmental constraints in fertilizer application.
Based on the results, specific recommendations for doses and ratios of fertilizers are developed, but even in this case it is necessary to correct the doses in relation to a specific enterprise, agrocenosis and field.
This group of methods also includes calculations of doses according to the standards of mineral fertilizer inputs for the whole crop according to the formula:
D = Y⋅H1⋅Kn,
or an increase in the harvest:
D = ΔY⋅H2⋅Kn,
where D – the dose of N, P2O5, K2O for the desired yield or gain, kg/ha a.s.; Y and ΔY – desired yield or gain respectively, t/ha; H1 and H2 – rates of fertilizer costs per unit yield and gain, kg a.s.; Kn – correction factor for soil class of phosphorus and potassium availability; when calculating nitrogen doses Kn = 1.
Norms of fertilizer application and correction factors to fertilizer doses are specified in the regional recommendations of research institutions, agricultural experimental stations, centers and stations of Agrochemical Service.
The third direction of the group of methods based on the generalization of data with empirical doses of fertilizers is the search for mathematical dependencies of yield on doses of fertilizers. The first such attempt was made in 1905 by German scientist E.A. Mitscherlich, who proposed the following equation:
lg(A – Y) = lgA – K⋅x,
where A – the maximum possible yield; Y – the actual yield; K – the coefficient of proportionality, which characterizes the relationship between yield and fertilizer dose; x – fertilizer dose.
The fourth direction of the group of methods is the development of regression models based on the results of planning, carrying out and statistical evaluation of the results of multifactor experiments with empirical doses of fertilizers. Equation with powers of 0.5 and 1 for factors and 0.5 for pairwise interactions proved to be the best mathematical model for determining quantitative dependence between yield and fertilizer doses:
Y = а0 + а1N0,5 + a2N + a3P0,5 + a4P + a5K0,5 + a6K + a7(NP)0,5 + a8(NK)0,5 + a9(PK)0,5,
where Y is yield; a0 is a free term of the equation; a1, a2, …, a9 are terms of the equation characterizing the effect and interaction of factors; N, P, K are fertilizer doses.
The fifth direction of this group of methods is the development of mathematical models with the use of computer technology to determine the optimum doses of fertilizers for crops, taking into account the functional dependence on many environmental factors:
Y = f(xn),
where Y is the yield; xn are the variables affecting the yield, such as doses and ratios of fertilizers, soil class and granulometric composition, weather conditions, varietal characteristics, predecessors, etc.
Various research institutions, based on the generalized results of field experiments, analyses and observations, have developed software packages for determining fertilizer doses. Thus, CINAO developed the RADOZ (abbreviation for “rational doses”) software complex, which was upgraded to RADOZ-2 and later to RADOZ-3. The modernization is related to the increase in the number of factors affecting crop yields.
Practical application of any of these methods and modifications makes it possible to avoid gross errors in the application of fertilizers. However, they are determined empirically without taking into account the biological needs of crops in nutrients and do not provide an answer to the question of soil conditions; according to them, despite the correction factors, it is impossible to quantify the balance of elements without special calculations.
Methods based on the generalization of data using balance sheet calculations
In this group of methods the biological characteristics of crops and varieties in the consumption of nutrients to create the planned high quality yields with simultaneous regulation of soil fertility (class, cultivation) for specific natural-economic conditions are the basis for determining the optimal doses of fertilizers. Consumption of soil nutrients and fertilizers by crops is determined by the results of field and production experiments, which transforms the field method from empirical to analytical, which allows to pass from the statement of yield increments to the prediction of their efficiency.
This group of methods is promising first of all for regions with sufficient moisture and irrigated agriculture, where the limiting factor for high and sustainable yields is the lack of nutrients, and fertilizer availability is high enough – not less than 100 kg/ha a.s.
Detailed soil characteristics are available in soil and agrochemical maps, which should be in each farm. The use of soil nutrients by specific crops is determined by coefficients of utilization (CUE) or by correction factors to the doses depending on the fertility of a particular soil.
Differences in effective fertility and cultivation of soils can also be taken into account through differentiated balance coefficients of use of mineral and organic fertilizers of relative balance indicators, i.e. return coefficients, intensity of balance and difference coefficients of fertilizer use.
There are many methods and modifications of balance calculations to determine optimal fertilizer doses.
Table. Differentiated by soil fertility differential coefficients of the use of nutrient elements of organic and mineral fertilizers in Non-Black Soil Zone (average for the rotation of crop rotations), % Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Ed. by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
Example. It is necessary to determine optimal doses of mineral fertilizers in combination with 20 tons/ha of half-decomposed manure containing 0.4% N, 0.2% P2O5 and 0.5% K2O to obtain 4.0 t/ha of grain with a grain:straw ratio of 1:1.5, winter wheat variety Mironovskaya 808 on sod-podzolic medium loamy calcareous soil with phosphorus and potassium (according to Kirsanov) respectively 70 and 100 mg/kg (3rd class) and salt extract pH 6.2 (6th class), precursor – vetch-oat mixture, under which N60P60K60 was introduced.
Maps of soil hydrolysable and mineral nitrogen supply are usually not made due to the high variability of these indicators even during one month, so the provision of soil with hydrolysable nitrogen is determined analytically or tentatively by the content of organic matter, total nitrogen or by phosphorus or potassium, which are at a minimum. Since the content of nitrogen in humus is an average of 4%, and, according to generalized information of the All-Russian Institute of Fertilizers and Agrochemistry, its hydrolysable forms of 4-7%, then at 2.5% of soil humus content of total nitrogen will be 0.1%, and hydrolysable – 0.004%, or 40 mg/kg. In order to determine nitrogen availability for the element that is in the minimum according to the adopted soil classification, its content corresponding to the same class as the element that is in the minimum is used.
In all methods and modifications determine the economic removal of a crop or variety in nutrients to create the planned yield at the cost per unit of the main and the corresponding amount of by-products from zonal, regional directories and recommendations. Or select a field in the farm, where a close level of yield of a variety is already achieved, take samples of grain and straw and subject them to chemical analysis. At the content of N, P2O5 and K2O in grain, respectively, 2.5; 0.8 and 0.6% and in straw 0.5; 0.2 and 1.2%, the economic yield with the planned yield will be:
N 130 (2,5-40 + 0,5-60) kg,
Р2O5 46 (0,8-40 + 0,2-60) kg,
К2O 96 (0,6 -40 + 1,2-60) kg,
and the cost of 1 ton of grain with the corresponding amount of straw, respectively, N 130:4 = 33 kg, P2O5 46:4 = 12 kg, K2O 96:4 = 24 kg.
Then the main methods are calculations of the elementary balance, on the surplus, on the relative indicators of the balance, based on one or a combination of several methods.
Elementary balance method
The method of elementary balance is the most common and the least accurate method, because it uses highly variable under the influence of many factors coefficients of use of soil elements (CUE) and more stable differential coefficients of fertilizer use. The calculations are carried out according to the formula:
where D – dose of N, P2O5 and K2O, kg/ha a.s.; RY – economic removal of an element with the planned yield, kg/ha; S – stock (content) of mobile forms of an element in the soil, kg/ha; KU – coefficient of element use from soil, fractions of one (at 10% – 0.1; 20% – 0.2, etc.); W – amount of an element in organic fertilizer, kg/ha; KW – difference coefficient of organic fertilizer element use, fractions of one; P – amount of an element in forecrop fertilizer and/or in post-harvest forecrop residues, kg/ha; K1 – difference coefficient of fertilizer and/or forecrop residues use, fractions of one; E – pre-sowing (row) fertilizer, kg/ha a.kg/ha; KE – difference coefficient of utilization of pre-sowing fertilizer, fractions of one; K2 – difference coefficient of fertilizer utilization at pre-sowing application, fractions of one.
For this example, optimal doses according to this method on the background of 20 t/ha of manure are as follows:
This method is widespread because it accounts for all nutrient inputs and outputs.
The elementary balance method takes into account:
- nutrient removal by the crop;
- content of mobile nutrients in the soil;
- coefficient of utilization of nutrients from soil;
- coefficient of nutrient use from fertilizers;
- mass of arable soil layer or soil layer for which the calculation is made.
Agrochemical indicators of soil supply maps of nitrogen, phosphorus and potassium in mg per 100 g of soil are translated into kg/ha by multiplying by the coefficient corresponding to the soil difference and the depth of the calculated arable layer. For example, for the 0-22 cm tilled layer of sod-podzolic soils it is 30, that is the mass of 1 ha of tilled layer of sod-podzolic soil is considered equal to 3000 t, for a layer up to 30 cm – the coefficient is 40.
This balance method is also applied with clarifications and modifications. Objectivity of the method depends on the reliability of the listed data, which can vary significantly depending on soil properties, weather conditions, doses and forms of fertilizer, term and method of application and other factors.
Method of calculations on the planned yield
The method of calculations on the planned yield increment is more accurate method compared to the previous one, as it takes into account the provision of soil with nutrients with the help of correction factors to doses, which are less dependent on various factors than the coefficients of useful use. However, for this method it is necessary to know the yield without fertilizers, which is best determined by data from experiments with fertilizers, based on which in the case under consideration it is equal to 2.0 t/ha. The yield can also be determined by the element that is in the minimum, using the coefficient of its use (CUE). The calculations are carried out according to the formula:
where D – the dose of N, P2O5 and K2O, kg/ha a.s.; Rp – element removal with the planned yield increase, kg; W – amount of element in organic fertilizer, kg/ha; KW – difference coefficient of organic fertilizer element use, fractions of one; P – amount of element in the predecessor fertilizer and/or post-harvest residues of the preceding crop, kg/ha; K1 – difference coefficient of fertilizer and/or residues of the preceding crop, fractions of one; E – pre-sowing (row) fertilizer, kg/ha a.s.; KE – difference coefficient of use of pre-sowing fertilizer, fractions of one; K2 – difference coefficient of use of fertilizer at pre-sowing application, fractions of one; K3 – correction coefficient to dose depending on soil class, (for the 3rd class for cereals, legumes and grasses equals 1).
For the above example according to this method optimal doses of mineral fertilizers on the background of 20 t/ha of manure will be:
In the above methods, when calculating fertilizer doses for the planned yield or increment, the fertilization of the preceding crop must be taken into account. If the preceding crops were grown on fertilized soils, to the soil nutrients calculated from the yield of the crop in the current year, add the effect of fertilizers applied at a rate of 10-15% of the original amount of the active substance in them.
For example, on unfertilized soil you get 20 tons/ha of green mass of corn, which yields 50 kg N, 20 kg P2O5 and 70 kg K2O. Corn is placed after the sugar beet, under which 150 kg N, 80 kg P2O5 and 150 kg K2O were brought; 15% of this amount will be 22,5 kg N, 12 kg P2O5 and 22,5 kg K2O. Thus, placing corn after the sugar beet, you can harvest about 30 tons/ha of green matter without additional fertilization. With a planned yield of 50 t/ha, the estimated dose for the formation of an additional 20 tons of green mass will require an additional 50 kg N, 20 kg P2O5 and 70 kg K2O.
Calculation of optimum doses with the help of balance coefficients of fertilizer use, differentiated by soil fertility
Calculation of optimum doses with the help of balance coefficients of fertilizer use, differentiated by soil fertility is the best method, because it allows you to simultaneously regulate the provision of soil with nutrients. Calculations to obtain the planned yield are carried out according to the formula:
where D – the dose of N, P2O5 and K2O, kg/ha a.s.; RY – economic removal of the element with the planned yield, kg/ha; W – the amount of element in the organic fertilizer, kg/ha; K1 – the difference factor of fertilizer and/or residues of the previous crop, fractions of one; K2 – the difference factor of fertilizer use at preplant application, fractions of one.
On the background of 20 t/ha of manure, mineral fertilizer doses are as follows:
Calculation of optimum fertilizer doses with return rates or balance intensities
The calculation of optimum fertilizer doses with return rates or balance intensities is more complicated, because these indicators are difficult to take into account the effect of fertilizers by years: for this purpose additional indicators are introduced, such as distribution coefficients of fertilizer action by years, which are derivatives of difference coefficients and have the same disadvantages.
Methods for determining doses of fertilizers, taking into account the annual increase in soil fertility and the removal of a nutrient element by the crop
Example. D = 80 kg/ha – amount of fertilizer (a.s.) to be applied annually to the soil; L = 4 years – number of years after the survey; R = 30 kg/ha – removal of nutrients on average per year, kg/ha; C = 50% (0.5) – proportion of the nutrient element going to replenish soil nutrients in the arable layer, from the value characterizing the positive balance; I – planned increase of the nutrient element, mg per 100 g of soil in the arable layer.
Content of nutrition elements in arable layer equivalent to 1 mg per 100 g of soil equivalent to 30 kg of phosphorus in arable layer is equal:
that is in 4 years phosphorus reserves in the soil increases by 3.3 mg per 100 g of soil, or annually by 0.8 mg per 100 g of soil. Using this formula determine the dose of phosphorus fertilizer (kg/ha), assuming that the average yield of phosphorus will be 30 kg/ha per year and its content in the soil should increase in 5 years by 4 mg/100 g (I), for example:
This method allows you to determine the dose of fertilizer for the planned yield, as well as the rate of growth of nutrients in the soil and its state of cultivation.
According to N.N. Mikhailov’s method, fertilizer doses for cereal crops on soils with low nutrient content, and for row crops – with average content are calculated for the planned yield, taking into account the increase of soil fertility.
Calculations of phosphorus and potassium requirements for the planned yield of winter rye are presented in the table.
Table. Demand and supply of phosphorus and potassium in winter rye yield planning 4 t/haAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
|needed to form a harvest, kg|
|Possible removal from the soil, kg|
|is required to provide at the expense of fertilizers|
|Supply with 20 tons of manure|
|Mineral fertilizers are required|
Nitrogen in this case is better optimized using the NMIH method (see “Nitrogen fertilizers“).
Although this method takes soil fertility into account when calculating nutrient requirements for the planned yield, it is also not highly accurate, as it uses too wide ranges of plant use of phosphorus and potassium from the soil. Also rather relative coefficients of nutrient use from organic and mineral fertilizers are taken.
Over a rotation, mineral fertilizer nitrogen is used by an average of 60%, phosphorus by 35% and potassium by 75%. Nitrogen and phosphorus of organic fertilizers is used by 50%, potassium – by 75%. Systematic determination of nitrogen, phosphorus and potassium content in the crop allows for annual adjustment of utilization rates and compilation of more reliable balances of nutrients.
The balance data allows you to more accurately calculate the dose of mineral fertilizers, depending on the specific conditions and the goal. Doses of fertilizer calculated to obtain the planned yield and a given content of nutrients in the soil are determined by the formula:
where D – nutrient dose, kg/ha; R – nutrient removal by the planned harvest, kg/ha; K1 – coefficient of nutrient use with regard to aftereffect; SS – the specified nutrient content in the soil, mg/100 g; SF – actual nutrient content in the soil, mg/100 g; K2 – coefficient of conversion mg/100 g to kg/ha; K3 – coefficient of fertilizer consumption to increase nutrient content in the soil; t – time for which the target nutrient content in the soil is to be obtained.
Example. It is necessary to obtain 4 t/ha of grain of winter wheat and achieve in 10 years, the actual content of phosphorus (SF) 10 mg per 100 g of soil. With a grain yield of 4 t/ha, winter wheat takes out 48 kg/ha of P2O5 (R). To determine the dose of phosphorus, removal (48 kg/ha) divided by the coefficient of its use by plants from fertilizers, taking into account the effects, provided that 2/3 of phosphorus is made with mineral and 1/3 with organic fertilizers, the coefficient of use is 0.4 (K1). In this case you need to apply 120 kg/ha of P2O5.
The average content of mobile phosphorus for 10 years (t) increase to 10 mg, or 5 mg per 100 g of soil (SS), which corresponds to 150 kg/ha (5 mg⋅30).
According to long-term studies, about 0.4 of the amount of phosphorus (K3) applied in excess of the dose for the planned yield goes to increase its assimilable forms in the soil. To achieve a given level of content of mobile forms of phosphorus in the soil over 10 years will require 375 kg/ha of P2O5 (150 kg: 0.4), or an average of 37.5 kg/ha for the year while maintaining the level of planned yields. Given this amount, the required dose calculated to obtain the planned yield and a given nutrient content will be 157.5 kg/ha (120 + 37.5):
Calculation of fertilizer doses according to soil evaluation
T.N. Kulikovskaya recommends to calculate fertilizer doses according to the point assessment of soils. On the basis of experimental data the price of arable land score, kg of production per score was developed.
Example. Planned yield of winter wheat 5 t/ha of grain. Soil is sandy loamy, arable score Sa = 58, price score for winter wheat PS = 34 kg.
Agrochemical properties of the soil: pH 6.0; humus – 1.8%; P2O5 – 14 and K2O – 12 mg per 100 g of soil; bulk weight 1.3 g/cm3; weight of 20 cm of arable layer 2600 t. Correction factor for agrochemical properties K = 1.23.
First, determine the amount of yield that can be obtained at the expense of effective soil fertility:
Y = Sa⋅PS⋅К = 58⋅34⋅1,23 = 2.42 t/ha.
Consequently, when fertilizer is applied, grain gain will be 2.58 t/ha (5.0-2.42) (table).
Table. Calculation of fertilizer doses for the planned yield of winter wheat 5 t/ha dry matter from 1 haAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
|Planned increase in grain yield, t/ha|
|Removed from 100 kg of grain, kg|
|Total yield per increment, kg/ha|
|Utilization factor from mineral fertilizers, %|
|Required to contribute with regard to the utilization factor, kg/ha|
Thus, to get 5 tons of grain we put N151P124K143, or a total of 418 kg/ha NPK.
According to studies of the Belarusian Research Institute of Soil Science and Agrochemistry, for different soils determined the payback of mineral and organic fertilizers.
Table. Recoupment of fertilizers by yield, kg production per 1 kg NPK and 1 ton of organic fertilizersAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
Using rates of recoupment of a unit of nutrients, calculate the dose of fertilizer for an additional yield of 2580 kg of grain of winter wheat. So, for 1 kg of NPK applied to loamy soil, 6 kg of grain, 2580 kg will require 430 kg/ha (2580:6). Knowing the optimum ratio of nutrients, which for winter wheat is N:P:K = 1,0:0,9:1,2, respectively – for 5 tons/ha of grain N139P125K166.
The calculation method is based on a large number of experimental data, and the dose is largely consistent with the biological characteristics of the crop.
Method for determining the really possible yield
The method for determining the really possible yield (RPY) by the content of nutrients in the soil was proposed by Ermokhin, Neklyudov, and Krasnitsky in 2000. The method is based on the fact that the content of nutrients in the soil is a limiting factor and determines the really possible yield.
The approach of the method allows us to estimate the natural fertility of the soil and determine the possible yield without fertilizers and then predict the effectiveness of fertilizers.
The authors propose a formula for the calculation:
where RPYNS – really possible yield due to soil nutrients (without fertilizers), t/ha; m – nutrient content in the soil, which is in the minimum, mg/100 g; h – depth of arable layer, cm; d – volume mass of arable layer, g/cm3; Ku – coefficient of plant nutrient use from soil; H – nutrient consumption by plants to create a unit of main production, including the side, kg/t.
In addition to the content of nutrients in the soil it is necessary to know the ratio of elements that take part in the formation of yield and their availability to plants.
For the conditions of Western Siberia the ratio of nutrients in the soil, which characterizes the balanced nutrition and allows to determine which of the elements is in the first minimum, was determined.
The optimum ratio of these elements in the soil layer 0-30 and 0-40 cm is equal:
P2O5 mg/100 g ≈ 10⋅NO3 mg/100 g ≈ K2O mg/100 g.
The balanced ratio of P2O5:NO3 is 10, P2O5:K2O is 1. If the P2O5:NO3 ratio is less than 10, it indicates a phosphorus deficiency, if more than 10, the soil contains nitrogen in the minimum. The ratio of K2O to NO3 is similarly characterized.
To determine which element is at a minimum, the action factor of the element to be applied as a fertilizer is established. The highest action coefficient (Kd) indicates that this element is at a minimum and will limit the yield of the cultivated crop.
Example. When the content in the soil N-NO3 – 0.7 mg/100 g; P2O5 – 10.5 mg/100 g; K2O – 10.0 mg/100 g; the ratio of nutrients will be: P2O5:N-NO3 = 10.5:0.7 = 15; K2O:N-NO3 = 10.0:0.7 = 14.3. Consequently, the limiting crop yield on this soil is nitrogen.
When using fertilizers the authors recommend for the soils of Western Siberia to use the optimal levels of nutrients established for grain crops A.E. Kochergin (mg/100 g): N-NO3 – 1,5; P2O5 – 15,0; K2O – 15,0.
The coefficient of action of a nutrient element can also be determined by another method: by the ratio of the optimal and actual content of the nutrient element in the soil:
From these data, it follows that the limiting factors limiting yield in this soil are all three nutrients, most of all nitrogen, as the Kd of nitrogen has the highest value of 2.14.
For Siberia Y.I. Ermokhin with co-authors (2000) give the following coefficients of utilization of nutrients by plants from soil reserves: nitrate nitrogen – 0,6-0,8 (60-80%), mobile phosphorus – 0,1 (10%), exchangeable potassium – 0,2-0,3 (20-30%). Knowing these indicators, determine the really possible yield (for example, barley) without the use of fertilizers.
N-NO3 = 0,7 mg/100 g
P2O5 = 10,5 mg/100 g
K2O = 10,0 mg/100 g
h = 30 sm
d = 1,2 g/sm3
HN = 35,6 kg/t
HP = 12,1 kg/t
HK = 25,1 kg/t
КП N = 0,6
КП P = 0,1
КП К = 0,3
Determine the RPY, t/ha = ?
Taking into account the current nitrification (NT = 70 kg/ha) RPY will be in nitrogen:
Consequently, with this characteristic of the soil, the possible barley yield would be 1.6 t/ha.
Methods of calculating fertilizer doses for the planned yield (N.K. Boldyrev)
N.K. Boldyrev in 1962 on the basis of complex methods of leaf and soil diagnostics proposed methods of calculation of fertilizer doses for the planned yield.
A simplified method of calculating fertilizer doses according to the chemical composition of leaves and mobile nutrients of soil is based on establishing the degree of need (DN) for a nutrient element by equation:
DN = OC : AC,
where OC is the optimal content of the element, AC is the actual content of the element.
The degree of need is specified by another element in relative abundance, or by the optimal ratio between the norms of elements in the leaves, given the equality:
%N (L) = 12% Р (L) = 1,2% К (L) or %N (L) = 5,2% P2O5 (L) = %К2O (L).
%N = 12⋅%P = 1,2⋅%K = 12⋅%S = 12⋅%Mg = 6⋅%Ca.
N.K. Boldyrev called the equation of the optimal balance of elements in the leaves of cereal crops during the flowering phase. The optimal ratios of elements for other crops have been developed.
Table. Indicators of normal levels of elements and the optimal ratio between them in the leaves of some cropsAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
|Spring and winter wheat|
|Corn for silage|
|Corn on grain|
|Sunflowers for grain|
|Cereal perennial grasses|
*In parentheses is the value of the coefficient of action of the balanced element in the leaves (CABEL, or “B”), corresponding to a certain level of plant yield
N.K. Boldyrev gives three tables with the ratio of NPK in leaves in three growth phases: tillering, piping, and the end of flowering. In the center of each table the optimal ratio of elements (NPK in leaves in the three growth phases) is given. Up and down from the center grows the imbalance associated with element deficiency (degree of need < 1) or excess (degree of need > 1).
Table. Ratio between nitrogen and phosphorus (% P) in leaves (tillering, tubing and late flowering phases) as a basis for assessing nutritional conditions and determining the degree of need (DN) and fertilizer rates for cereal crops (by N.K. Boldyrev)
Table. Ratio between nitrogen and potassium (% K) in leaves as a basis for assessing nutritional conditions, determining the degree of need (DN) and fertilizer rates for cereal crops (by N.K. Boldyrev)
Table. Ratio between potassium (% K) and phosphorus (% P) in leaves as a basis for assessing nutritional conditions, determining the degree of need (DN) and fertilizer rates for cereal crops (by N.K. Boldyrev)
Knowing the Needs Degree (DN) values, determined by the equation DN = OC : AS or tables, you can calculate the fertilizer dose.
If DN < 1, the plants do not need this element and the calculation of a dose is not carried out. If the value of DN is from 1.1 to 3-4, the indicator is included in the formula:
D (kg/ha) = DN ⋅ MN,
where D is the dose of the active substance (a.s.); MN is the minimum dose (kg a.s.) used in the main fertilizer, the value of which is set in field experiments.
The value of MN in the basic fertilizer for cereals, corn and peas is usually 30 kg/ha a.s., for potatoes and vegetables – 45 kg/ha a.s. under normal growing conditions to get the yield to 4 t/ha of grain, 25 t/ha of potatoes and 50 t/ha of cabbage. Under irrigation conditions the minimum dose (MN) can be 1.5-2 times more. In the complex method of leaf diagnostics the dose adjustment of the missing element by other basic elements in some excess or deficiency is given.
Example. Calculation of nitrogen rate to produce 4 t/ha of spring wheat grain.
For the tillering phase optimum content in leaves N = 5%, P = 0.43%, K = 4.2%. Equilibrated element (nitrogen) action coefficient in leaves B = 0.5 for 3.2-4.0 t/ha yield, 0.63 for 4.1-5.0 t/ha yield, and 0.8 for 5.5-6.0 t/ha yield. Nitrogen requirement of spring wheat per 100 kg of grain with 4 kg of straw. The coefficient of use from mineral fertilizers N – 63%, P2O5 – 20% and K2O – 63%. Minimum nitrogen rate NMIN = 45 kg.
For the phase of the end of flowering the optimal content of elements in the leaves N = 3%, P = 0.25%, K = 2.5%. The coefficient of action of elements in leaves (B) for yields of 4.0 t/ha is 0.8, for yields up to 5.0 t/ha of grain is 1.0, for yields of 5.1-6.0 t/ha is 1.25. Other indicators are the same as for the tillering phase.
The actual indicators of the chemical composition of leaves of the unfertilized variant in the phase of tillering are N = 3.92%, P = 0.46%, K = 4.3%, in the phase of the end of flowering N = 2.10%, P = 0.29%, K = 3.74%.
Then, for the tillering phase the degree of need for nitrogen is:
For the late blooming phase, the degree of nitrogen requirement will be:
This degree of wheat’s need for nitrogen must be corrected for the lack of phosphorus in the leaves or in the soil if this deficiency cannot be overcome. Considering that the degree of need N = 1.7,
From there, the nitrogen dose would be N kg/ha = DN ⋅ 45 = 1.02 ⋅ 45 = 46 kg/ha instead of 80 kg/ha. This correction is important when determining nitrogen doses for winter and spring crops whose fields have less than the norm content of mobile phosphorus or potassium.
Thus, the dose of nitrogen by leaf chemistry in the phase of tillering is N kg/ha = DN ⋅ MN = 1.4 ⋅ 45 = 63 kg/ha, in the phase of end flowering N kg/ha = DN ⋅ MN = 1.7 ⋅ 45 = 76 kg/ha, the average – 70 kg/ha.
If we take into account the excessive content of potassium in leaves compared with the optimal content, then
and the nitrogen dose will be N = 2.1 ⋅ 45 = 94 kg/ha.
According to the sum of the three calculations, adjusted for some excess of phosphorus and potassium in the two phases of growth, the nitrogen rate will average (63 + 76 + 94) : 3 = 78 kg/ha.
By analogy with the complex method of analytical leaf diagnosis N.K. Boldyrev recommends to calculate fertilizer doses by the content of mobile nutrients in the soil, i.e. to apply a complex method of soil diagnosis. The method is based on determining the normal nutrient composition of the “soil”, which provides a high yield of grain, for example, 4 t/ha of grain of spring wheat. They can be called the optimal parameters of soil fertility by mobile forms of nutrients.
Table. Indicators of the normal nutrient composition of different types of soils, ensuring the receipt of 4 tons of spring wheat and the corresponding level of yield of other cropsAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. - 854 p.
*For yield levels of 5.0-5.5 t/ha of winter wheat grain, the content corresponds to 35 mg/kg of soil
The table is supplemented by indicators of the optimum ratio between the elements in the soil, which are necessary for subsequent calculated adjustments of fertilizer doses by ratios between mobile nutrients.
Table. Relationship between mobile nutrients in the soil as a basis for assessing nutritional conditions and determining the degree of need for fertilizers cereal cropsAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
*NO – nutritional optimum in terms of nutrient ratios. Designations: 1 NO – balanced nutrition, defined by the equation: mg/kg P2O5 – 7,2⋅Nnit mg/kg K2O; 2 – nutrition imbalance is weak; 3-4 – medium; 5-7 – strong.
Table. Relationship between potassium and nitrate nitrogen in the soil as a basis for assessing nutritional conditions, determining the degree of need DN and norms of the missing element in fertilizerAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al; ed. by V.G. Mineev. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, … Continue reading
Table. Ratio between mobile phosphorus and exchangeable potassium (according to Chirikov) as a basis for assessing nutritional conditions and determining the degree of need of DN in the missing elementAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. - 854 p.
N:P2O5:K2O ratios in soil characterize the qualitative side of plant nutrition and its balance. The ratio between the optimal and actual content of Nnit and P2O5, between Nnit and K2O is expressed by quantitative indices of the degree of need for the missing element, which are used as correction factors for adjusting the fertilizer rate.
Optimal ratios between mobile nutrients of the soil are set in field experiments with varying doses of fertilizers on the factorial or conventional schemes by determining the correlation relations graphically or by grouping between the indicators of relations of pairs of elements and the amount of yield. Optimal ratios between mobile nutrients of soil for grain crops on some types of soils are expressed by the equations of nutrient balance.
For ordinary and leached chernozems (Chirikov’s method for phosphorus and exchangeable potassium) equality:
P2O5 mg/kg of soil = 7,2⋅N-NO3 mg/kg = K2O mg/kg.
For carbonate chernozems and chestnut soils (Machigin’s method for phosphorus and potassium):
Р2O5 mg/kg of soil = N-NO3 = K2O : 10.
Indicators of optimum soil nutrient composition and optimum ratio between mobile nutrients are used to determine fertilizer doses in other calculation methods as well. Calculation of fertilizer doses according to agrochemical soil analysis is carried out by analogy with the method of leaf diagnostics.
The norm of the missing element is determined by multiplying by the minimum dose of MN element, equal to 30.
For nitrogen under irrigation conditions Mn is differentiated taking into account the planned yield and is: MN = 30 for yields up to 3.6-3.8 t/ha; MN = 45 for yields 4.0-5.0 t/ha and MN = 60 for yields above 6.0 t/ha. For phosphorus MH under irrigation is 45 kg P2O5.
Initial data of soil analysis are taken for ordinary chernozem and getting the planned yield of spring wheat grain at irrigation 4.0 t/ha. Humus content in the layer 0-30 cm is 6.0%, the content 7-10 days before sowing nitrate nitrogen (N-NO3) – 14.0 mg/kg; P2O5 and K2O (by Chirikov) – 182 and 1176 mg/kg respectively. The volume mass of 1 cm3 of the analyzed layer d = 1.05, the depth of the analyzed layer h = 30 cm. Mass of the analyzed soil layer in million kg per 1 ha to convert nutrients from mg/kg to kg/ha, i.e. the conversion factor for the mass of the layer Ml, is determined by the formula:
For chestnut soil and irrigation for nitrate nitrogen using 0-60 cm definition layer at d = 1.2 g/cm3, Ml will be 7.2.
Procedure for determining the fertilizer dose
1. Comparison of actual data on N-NO3, P2O5 and K2O with optimum values – 25, 180, 180 mg/kg respectively indicates that wheat plants for 4.0 t/ha yield does not need phosphorus and potassium fertilizers and only need nitrogen.
2. The degree of plants’ need for nitrogen is determined using the equation
correction for phosphorus
The degree of needing N adjusted for the ratio of K2O and N-NO3 because of the excess of exchangeable potassium reaches a very large value.
Correction for potassium
Therefore, the equilibration of nitrogen nutrition is an excess of potassium in the soil, when the correction for potassium exceeds 3, DN for phosphorus is (180 : 182) = 0.99, and for potassium DN = (180 : 1176) = 0.15, that is, the need for these elements is absent.
3. The dose of nitrogen in the basic fertilizer is determined by the formula
DN kg/ha = DN ⋅ MN,
where DN = 1.8, the minimum dose (MN) is 30 kg/ha or 45 kg/ha of nitrogen, N kg/ha = 1.8 ⋅ 30 = 54, N kg/ha = 1.8 ⋅ 45 = 81.
These calculated doses equal to 54 and 81 kg/ha of nitrogen almost coincide with the optimal doses identified in field experiments. There was no need to apply phosphorus and potassium fertilizers.
Based on many years of research of Kazakh Agrotechnical University (KATU) made by V.G. Chernenok, gradations of soils by P2O5 content were corrected for conditions of Northern Kazakhstan.
Table. Gradation of dark chestnut and chernozem soils of Northern Kazakhstan on the content of P2O5 and the effectiveness of phosphorus fertilizersAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. - 854 p.
Application of balance methods of calculations
The disadvantage of all balance methods is that they do not take into account the previous crops, agrochemical indicators, the state of soil cultivation and other indicators affecting the coefficient of use of nutrients by plants from soil and fertilizer. Therefore, they are considered as indicative, especially if the data for calculations are taken from reference materials. In practice, they give satisfactory results and streamline the application of fertilizers.
The objective of the above calculation methods is to obtain a yield in the current year using the natural fertility of the soil. Fertilizers compensate for the amount of nutrients that cannot be obtained from the soil. In this case there is no systematic improvement of fertility and replenishment of nutrients that are used to form the crop.
Balance calculations of fertilizer doses for the planned yield, taking into account the increase in fertility, have options:
- Obtaining high yields by applying small doses with simultaneous depletion of soil nutrients.
- Obtaining high yields while maintaining effective fertility at the initial level.
- Obtaining the maximum possible yields of the given crop with simultaneous increase of effective fertility.
Determination of phosphorus fertilizer doses
Based on the correlation analysis of experimental data was established quantitative relationship between the content of nutrients in the soil and crop productivity, defined the optimal parameters for different crops and proposed a way to achieve them.
Table. Optimal levels of nutrients in the soil for different crops (V.G. Chernenok, 1993, 2009)
This allowed us to propose a new and more accurate way to determine the deficiency of phosphorus in the soil and fertilizer doses for crops by the optimization formula:
DP (kg a.s./ha) = (Poptimal – Pactual) ⋅ K,
where the difference (Poptimal – Pactual) shows the deficit of phosphorus in the field in mg/kg of soil, the coefficient of K = 10 in zonal soils, DP – the amount of phosphate fertilizers, which should be made to eliminate the deficit and create optimal conditions for nutrition phosphorus for crops in this field.
When calculating fertilizer doses, the lower indicator of the optimal level should be included.
If the phosphorus deficiency is very high and it is not possible to bring its content to the optimal level in one application, it can be done in several applications, bringing in the first stage to the average level – 25 mg/kg of soil.
Creating an optimal level of phosphorus in the soil allows the crop to realize the potential of forming the maximum yield in all conditions of moisture.
The optimum regime of phosphorus nutrition contributes to the effective consumption of moisture. For example, at a low level of nutrition on average over 20 years, the coefficient of water consumption was 20 mm, at an average – 12 mm, the optimum – 8 mm.
If there is a large deficit of phosphorus in the soil, when it is not possible to bring the content to the optimal level in one go, you can determine the dose of fertilizer for a certain increase in yield
Example. To increase the yield by 0,5 t it is necessary to increase the content of phosphorus in the soil by 6 mg (5 t⋅1,2 mg P2O5), for this purpose 60 kg a.s. of fertilizer (6⋅10) should be applied.
Table. Relation of spring wheat yield to P2О5 content in soil (KATU, Chernenok, 1970-1990).
|Consumption mg Р2О5 per 100 kg of harvest|
Determination of nitrogen fertilizer doses
Thanks to many years of research (Chernenok 1993,1997), 4 main factors of effectiveness of nitrogen fertilizers: nitrate content in the layer 0-40 cm, the content of mobile phosphorus, their ratio and moisture conditions were determined. A quantitative relationship between these factors has been established, which allows us to determine the needs of crops in fertilizers and ensure their effectiveness.
Taking into account these factors a zonal scale of soil nitrogen and phosphorus availability was developed.
Table. Gradation of grain crops nitrogen availability, according to the content of N-NO3 mg/kg of soil in the 0-40 cm layer (Chernenok V.G.)
To calculate the dose of nitrogen fertilizers, you need to determine the content of nitrate nitrogen in the soil in the 0-40 cm layer. If the content of hydrolysable nitrogen is known (according to Tyurin-Kononova), the index should be converted to nitrate nitrogen (N-NO3) by multiplying by the factor 0.26. For subsequent crops placed in the rotation after the fallow, the N-NO3 content according to the average annual data is reduced by 30%.
More accurately the nitrogen deficit in the soil and the need for nitrogen fertilizers is calculated by a formula which takes into account the biological characteristics of the crop, the requirements of the conditions of nitrogen nutrition and the nitrogen content in the soil N-NO3 mg/kg in the layer 0-40 cm (Chernenok V.G.):
DN = (Noptimal – Nactual) ⋅ K ⋅ Kmoisture,
where: DN – dose of nitrogen fertilizers, kg/ha a.s.; Noptimal – the optimum content of nitrate nitrogen in the soil, mg/kg in the layer 0-40 cm; Nactual – the actual content of N-NO3, mg/kg in the layer 0-40 cm; K – the equivalent of kg a.s. fertilizers 1 mg N-NO3 soil, equal to 7.5 kg (that amount of N fertilizers, which should be made to increase the N-NO3 in soil by 1 mg/kg); Kmoisture – moisture correction factor.
The formula assumes bringing the phosphorus content to an optimum level. If the P2O5 content in the soil even after the application of phosphate fertilizers remains below the optimal, which can be determined by dividing the dose of fertilizer applied by 10 (the equivalent cost of kg a.s. fertilizer to increase phosphorus in the soil by 1 mg/kg given the actual content of soil phosphorus):
P (mg/kg) = Pactual + DP/10,
where DP is the applied dose of phosphorus.
In this case, the dose of nitrogen fertilizer is calculated by the formula:
DN = (1/3Pactual – Nactual) ⋅ К ⋅ Kmoisture,
where (1/3Pactual) is an indicator of the level of N-NO3 mg/kg to which nitrogen should be brought, providing the optimum ratio of P : N, equal to 2.5-3.
Example. The soil contains 15 mg P2O5/kg of soil. We applied 120 kg a.s., the content of P2O5 increased to 27 mg (15 + 120/10). Optimal levels of phosphorus have not been reached, so you should not bring the nitrogen to 12 or 15 mg. For 27 mg of P2O5, the optimal N-NO3 content would be 27:3 = 9 mg.
This allows you to maintain the optimal phosphorus to nitrogen ratio for plants in phosphorus deficient soils. Which saves the amount of fertilizer and funds, as phosphorus deficiency will not allow to realize the full dose of nitrogen, designed to bring it to the optimum.
Kmoisture – correction factor for moisture, calculated by the formula:
Kmoisture = Aactual/275,
where: Aactual – actual (predicted) annual precipitation; 275 – normative precipitation, a constant value equal to the mean annual precipitation for the study period.
Actual (predicted) precipitation is calculated based on actual precipitation for September-May plus predicted precipitation for vegetation period. If in June the amount of precipitation is expected within the norm – the long-term average is added, if higher – 1.5 norm, lower – 0.5 norm.
Kmoisture allows to correct normative indicators and calculate dose and increment from nitrogen fertilizers for any wetting year within zonal variation of precipitation. These tables are applicable for all soils.
Table. Doses of nitrogen fertilizers and yield gains (100 kg/ha) depending on N content in soil and Kmoisture
More precisely the increase is determined by the formula:
IN = 1,24 – 0,14N-NO3 + 1,62 Kmoisture + 0,06P/N,
IN – increment from nitrogen fertilizers; N-NO3 – content in soil, mg/kg in 0-40 cm layer; P/N – ratio of actual P2O5 content, mg/kg of soil in 0-20 cm layer to N-NO3, mg/kg in 0-40 cm layer.
In market conditions it is important to know the possible yield increase, so that even before fertilizing, based on the prevailing prices, to determine how this method will be economically justified.
Correlation analysis showed high reliability (r = 0.93) forecast efficiency of nitrogen fertilizers, calculated by the method given, taking into account all 4 factors determining the efficiency.
Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. – Moscow: Kolos, 2002. – 584 p.: ill.
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.
- Fertilization system and soil-climatic conditions
- Zonal peculiarities of fertilizer systems
- Fertilizer efficiency depending on agrotechnical factors
- Efficiency depending on the amount and quality of fertilizer (Русская версия)
The effectiveness of fertilizers depends on the quantity (total rate) and quality (ratio of species, forms, methods and timing of application). The dependence is maintained as long as the lack of a nutrient remains a limiting factor for plant growth and development. With increasing the total rate and increasing soil fertility, the efficiency decreases.
Generalized A.I. Podkolzin (1998) for 30 years of long-term research in the Stavropol Territory with winter wheat confirms the decrease in fertilizer efficiency with increasing rates and fertility of black and chestnut soils.
Table. Winter wheat grain yield gains (t/ha) depending on fertilizer doses and soil nutrient supply
Application of fertilizers and ameliorants in dry conditions gives up to 20-30%, in conditions of insufficient moisture – up to 30-50%, and with sufficient moisture – up to 50-70% of total productivity of all cultivated crops.
By increasing the rates and improving the ratios (N:P2O5:K2O) the average annual yield of grain crops in some farms of the Moscow region increased from 1.1 to 4.6 t/ha. Only by improving the ratio of fertilizers corresponding to the needs of crops and soil fertility at 188 and 182 kg/ha a.s. yields increased by 0.6 t/ha, or 48%.
Even with optimal doses and ratios of nutrients, fertilizer efficiency depends on the forms, basic and associated elements, moisture content, solubility, granulometric composition, physiological and hydrolytic reactions.
With long-term use of organic and mineral fertilizers in crop rotations in equivalent doses of nutrients the productivity of crop rotations on chernozems, as a rule, is the same. On light sod-podzolic soils, organic fertilizers are more effective, on heavy and medium loamy – mineral. Maximum yields of vegetable, fodder and other crops are achieved with a combination of optimal doses of organic and mineral fertilizers, on acidic and alkaline soils also ameliorants.
The effect of once applied ameliorants, organic, phosphorus and, to a decreasing extent, potash and nitrogen fertilizers, depending on the rate, type and soil and climatic conditions is manifested for 4-5 years, sometimes at high rates – over 10 years.
On average, for 55 years on heavy loamy soils under cereal crops are more effective mineral fertilizers, under clover – manure, under potatoes – they are of equal value. By productivity of crop rotations the advantage of mineral fertilizers in experiment 1 (with pure fallow) and in experiment 2 (with clover fallow) is noted. The combination of half doses of manure and mineral fertilizers in the rotation with bare fallow (experiment 1) increases the productivity of crops in the rotation compared with the manure, bringing it closer to the variant with mineral fertilizers.
Table. Comparative efficiency of manure, mineral fertilizers and their combinations by crop rotation of sod-podzolic soil (summary by Hlystovsky, 1992)
|NPKCa (manure equivalent)|
|0.5 manure + 0.5 NPKCa|
Methods for evaluating fertilizer efficiency
Evaluation of the effectiveness of types, doses and combinations of fertilizers is carried out by the magnitude of additions, total crop yields and crop rotation productivity, the payback of 1 kg a.s. of fertilizers by yield increases and productivity of crop rotations. However, when the total doses are equal, but different types and ratios in obtaining equal increments or total yields of individual crops and productivity of crop rotations, as well as to determine the contribution of certain types of fertilizers in obtaining productivity, it is necessary to determine the use by crops of the nutrient elements of fertilizers. These estimates are calculated by different methods.
The isotopic method is the most accurate and shows the use of an element of the applied fertilizer. Based on the amount of labeled radioactive or stable isotope of an element delivered to the plants, the utilization factor is calculated from the total content in the applied dose of fertilizer:
where Kis – isotope coefficient of fertilizer use, %; Ris – economic, or biological, removal of labeled element isotope, mg/m2 or mg/unit; Dis – dose of labeled element isotope in fertilizer, mg/m2 or mg/unit; 100 – for conversion to %.
Isotope ratio is important in the study of the cycle, transformations and movements of fertilizer and soil elements in soil, plant, water, air, animals, as well as for an accurate assessment of the use of elements from fertilizers.
Fertilization increases the mobilization of soil nutrient reserves and plants absorb elements of the fertilizer applied and reserves in the soil. Therefore, along with the isotopic method, a more practically acceptable difference coefficient of fertilizer use is used.
The difference method is based on the results of field and production experiments with fertilizers and is suitable for determining optimum fertilizer doses and ratios. The difference coefficient of fertilizer use is the percentage ratio of the difference between the economic removals of elements in the fertilized (Rf) and not fertilized control (R0) variants to the fertilizer dose in the fertilized variant (Df):
Differential coefficients of use of elements of organic and mineral fertilizers in the first and subsequent years vary greatly even under the same crop and within the same field depending on the type, dose, ratios, form, timing and methods of application. With the same methods on the same soil, the coefficients of fertilizer use for crops with a poorly developed root system and a short growing season are lower than for plants with a more developed root system and a long growing season. Also under annual plants less than under perennials.
At local methods of fertilizer application under all crops in all soil and climatic zones the use of nutritive elements increases by 1.5-2.0 times in comparison with the scattered (continuous) method of application before sowing, before sowing and at root feeding. Phosphate water-soluble and complex fertilizers have higher rates of use from granular forms, and phosphate flour – with a finer grinding and thorough mixing with the soil.
The difference coefficients of fertilizer use (Kd) decrease for all crops when moving from poor to more fertile and cultivated soils, as well as when increasing fertilizer doses on all soils.
Thus, Kd under all crops, depending on conditions, can change: on average by 50-80% already in the first year after application. For practical purposes, it is sufficient to consider the effect of fertilizers for 3-4 years. In contrast to the one-year data Kd fluctuations in the total for 3-4 years is less due to the dissimilarity of weather conditions during these years and the biological characteristics of crops cultivated during this period.
Table. Differential coefficients of the use of nutrient elements of fertilizers (%) on medium fertile soils of the Central Black Earth RegionYagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
According to generalized long-term data, for medium-fertile soils of class 3-4 of the central regions of the Non-Black Soil Zone average differential coefficients of use of nutrients from organic and mineral fertilizers are applied.
Mineral and organic fertilizers, applied locally during planting or seeding, in the first year can be used by 50-80%.
The difference coefficients reflect the real consumption of the nutrient elements of fertilizer and soil by the fertilizer application by the crops. However, this consumption is compared with soil without fertiliser. Hence: the poorer the soil (without fertilizer), the higher the coefficients, the richer it is, the lower they are.
In reality, it takes more fertilizer to produce equal yields of any crop on poor soils than on cultivated ones, since on the former some of the fertilizer is absorbed by the soil and not by the crop or is lost. Endless exploitation of cultivated soils at low doses of fertilizer leads to impoverishment and loss of fertility. To prevent this, fertilizer application is controlled by using balance coefficients of nutrient use.
The balance method is based on determining the balance coefficient of fertilizer use (Kb):
where Rf is economic export of an element by the crop in the fertilized variant, in kg/ha, Df is the dose of fertilizer in kg/ha in this variant.
Balance coefficients are determined in experiments and production crops. They give an idea of the degree of assimilation by crops of nutrients from fertilizers and soil and possible changes in the provision of soils with these elements.
Table. Application and consumption of N, Р2O5, К2O in the crop rotation (bare fallow - winter crops - potatoes - oats) by DAOS on heavy loamy sod-podzol soils (average for 56 years on 4 fields; data of Khlystovsky, 1992)
Balance coefficients are higher than difference coefficients, and also higher on fertile soils than on poor soils, i.e. there are no disadvantages of difference and isotopic coefficients.
Balance results are also expressed in relative terms:
- return coefficient – the ratio of fertilizer dose to economic removal;
- intensity of the balance – the ratio of the dose to the economic removal, i.e. the return coefficient multiplied by 100.
The balance is expressed in absolute terms (kg/ha) as the difference between the dose and the economic removal of the element. Balance is positive if the dose exceeds removal or negative if the dose is less than removal. When the dose and removal are equal, the balance is called zero, or deficit-free, balanced.
Balance coefficient, return coefficient, and balance intensity are equal, respectively: at zero balance – 100, 1, and 100; at positive balance – less than 100, more than 1, and more than 100; at negative balance – more than 100, less than 1, and less than 100.
All relative indicators are equivalent only when the balance is zero, in other cases, the advantage remains for the balance coefficient, since its calculations are taken as the basis not dose of fertilizer, and economic removal, which characterizes the yield and product quality. Balance coefficients of fertilizer use can be determined for different years from the moment of application and to the end of the fertilizers, while the return coefficients and intensity of the balance – only at the end of the fertilizers, that is for most fertilizers – 4-5 years after application or during rotation of crop rotation, which is important for periodically applied fertilizers.
The use of balance coefficients allows to determine the optimum doses and ratios of fertilizers under individual crops and in crop rotations with simultaneous control and correction of soil provision with nutrients. Thus there is no need to calculate the balances of elements in fields, crop rotations, and farms.
For the Non-Black Soil zone of Russia recommended the following balance coefficients of mineral and organic fertilizers for soils of varying degrees of cultivation.
Table. Balance coefficients of mineral fertilizer use (%) on different fertility soils of Non-Black Soil zoneYagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
*The after-effect of nitrogen fertilizers is small, so they are taken into account in the 2nd-4th years in total
If mineral fertilizers are applied to all crops of the rotation, balance coefficients of mineral fertilizers in determining the optimal doses can not be taken into account by year, and take the sum for all years.
For organic fertilizers coefficients are selected taking into account the year of action, since these fertilizers are used, as a rule, not for all crops of the rotation.
Table. Balance coefficients of the use of elements of organic fertilizers (%) on soils of different fertility Non-Black Earth zone RussiaYagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. – Moscow: Kolos, 2002. – 584 p.: ill.
Fertilizer application methods
The task of fertilizer application methods is to ensure optimal plant nutrition conditions during the growing season. When choosing the application methods it is necessary to take into account the crop’s need for nutrients by growth phase and the possibility of placing them in the zone of greatest contact with the root system. On the choice of methods of fertilizer influences the properties of fertilizers, their mobility, features of interaction with soil-absorbing complex, the presence of impurities in the fertilizer and the attitude of crops. The placement of fertilizers in the arable layer depends on the method of application and embedding.
Table. Distribution of fertilizers (%) at incorporation by different implements on stubble cereal cropsYagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
|Plow with skimmer, 20|
|Plow without skimmer, 20|
|Plow with skimmer, 30|
|Plow without skimmer, 30|
|Тяжелая дисковая борона в два следа, 20|
|Cultivator with universal tines, 20|
|Cultivator with spring tines|
When the harrow is applied, 75-98% of the fertilizer is located in the upper soil layer at a depth of up to 3 cm. This method can be effective in the area of sufficient moisture or with irrigation on light soils, as well as surface feeding of crops of continuous sowing, such as winter wheat, with soluble and mobile nitrogen fertilizers. In steppe areas with insufficient and unstable moisture this method of embedding is ineffective.
When closing the fertilizer with a plow with skimmer most of the fertilizer is embedded in the lower layers of the soil, where they work well and are used by plants with sufficient development of the root system. However, at the beginning of the growing season the crop may experience a lack of nutrients. Therefore, in this case, there is a need for additional fertilizers to provide nutrition to plants in the first phases of growth.
Table. Placement of fertilizers (in %) in the arable soil layer depending on the method of embeddingAgrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. - M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. - 854 p.
When fertilizers are spread over the surface of the field, the incorporation of different tillage implements is unsatisfactory and does not meet the needs of crops. When cultivating even with the same implement, the distribution of fertilizers applied in a scattered manner over the soil profile depends on their physical properties.
The greatest effect under all crops is achieved when the local application of fertilizers to a given depth, which is usually not less than 8-10 cm for heavy soils and 12-15 cm for light soils with a granulometric composition. According to the summary of more than 20 years of the All-Russian Institute of Fertilizers and Agrochemistry, the yield of all crops from localization of equal doses of fertilizers increased by an average of 0.5-1.0 t / ha grain units, compared to scattered application, and more significantly under the intensive varieties of crops. At localization nutrients of fertilizers are more fully used by plants, their losses are reduced, doses of fertilizers can be reduced by 30-50% compared with a scattered application, thus increasing the fertilized area and efficiency by 2 times.
Fertilizer efficiency increases with the depth of embedding, with a decrease in moisture availability of crops. With the same moisture availability depends on the mobility of types and forms of fertiliser. Depth of embedding is important for organic and phosphorus, less – for potassium, nitrogen and micro fertilizers.
With sufficient precipitation the effectiveness of organic, phosphorus and potassium fertilizers, especially on sod-podzolic soils, increases with increasing embedding depth within the cultivated topsoil. At deeper treatment of such soils efficiency decreases as they are diluted with a large volume of soil poor in nutrients with unsatisfactory agrochemical and physical properties.
Fertilizer efficiency depends on the timing of the main tillage, especially for nitrogen fertilizers. For example, at late autumn tillage mineralization of root and crop residues because of the short period is minimal, so on such a background increases the effectiveness of nitrogen fertilizers.
The timing and methods of sowing (planting), the quality of seed (planting) material affect the efficiency of fertilizers. On cultivated fertile soils, yield losses when sowing is delayed by 1 day are 0.10-0.15 t/ha. The timing of sowing is primarily important in the southern regions of the country: optimal timing increases the resistance of crops to drought, dry weather, as well as early fall and late spring frosts. In the Non-Black Soil Zone, a delay in sowing for 10 days or more for most crops leads to lower yields, especially if there is a lack of moisture during the growing season.
The effect of fertilizers depends on the seed rate and the density of plant stand, i.e. on the feeding area of each plant. The optimum seeding rates and plant standings are given in reference books and depend on the cultivation of the soil. Within one plant species on the same soil, these rates vary depending on varieties, lodging resistance, and seed quality. Switching from high quality seeds of elite varieties to lower quality seeds reduces fertilizer efficiency.
Quality and timely work before sowing, at sowing, during the growing season and harvesting increases fertilizer efficiency. Creation of optimal conditions of plant nutrition by fertilizers and ameliorants increases their resistance to adverse factors, in particular to diseases, pests and weeds. Thus, mineral fertilizers increase resistance of barley to Swedish fly, winter wheat to Swedish and Hessian flies, all cereal crops, especially phosphorus, to root rot and brown rust. At the same time, nitrogen fertilizers, especially in their excess, can reduce the resistance of crops to diseases and pests.
Mutual influence of crop protection agents and fertilizers
Fertilizers in optimal rates and proportions reduce the activity of snow mold in winter crops and simultaneously increase the competitive ability of crops of continuous sowing, especially winter crops, in relation to weeds. Mineral fertilizers alone and in combination with organic fertilizers increase the resistance of potatoes to phytophthora, rhizoctoniosis and potato scab. Although the latter appears more often with liming of soils, it can be suppressed by boric fertilizers. Fertilizers do not replace plant protection by biological, chemical and agrotechnical means.
Weed infestation of crops reduces the yield of cultivated crops due to competition of weeds for nutritional conditions. Weeds, because of their different and greater need for nutrients than cultivated plants, change the populations of the predominant species when fertilizing crops. Therefore, the predominance of one or another type and form of fertilizer allows you to predict the predominant weed species and adjust the system of weed control measures.
Thus, the elimination of weeds by available methods indirectly affects the effectiveness of fertilizers.
It is possible to apply fertilizers and root herbicides together under the preplanting treatment. Treatment with herbicides is also combined with top dressing of winter cereals and perennial grasses with nitrogen fertilizers as well as with foliar dressing with nitrogen and microfertilizers combined with fungicides, insecticides and plant growth regulators.
In a series of field experiments with maize on sod-podzolic and gray forest soils summarized at the Agrochemistry Department of the Moscow Agricultural Academy, weeds reduced fertilizer efficiency in crops by 5 times, herbicides increased fertilizer efficiency by more than 4 times compared with weedy crops, but were less effective than manual weeding of crops.
Herbicides also have a depressing effect on the protected crop, but the harm from weeds is more significant, so chemical weeding is very effective.
Optimization of rates and proportions of fertilizers for a particular crop increases competitiveness to weeds, to applied herbicides and other adverse environmental factors. Thus, under complex influence of doses of fertilizers (N43P33K74 and N86P66K148), simazine (before sprouts) and 2,4-D (on sprouts) on gray forest soils the corn green mass yield (the yield without fertilizers with one-time manual weeding was taken as 100%) was in fertilized variants without herbicides – total 83% and 115%, including milk-wax cobs 105% and 151%; the same + one manual weeding 131% and 124%, including cobs 170% and 186%; fertilizers + simazine 131% and 151%, 221% and 232%; the same + 2,4-D 160% and 164%, 307% and 230%. The most effective was the first dose of fertilizer combined with simazine before sprouting (2 kg/ha) and butyl ether 2,4-D after sprouting (0.6 kg/ha). The total weight increased by 1.6 times, the cobs by 3 times compared to the variant without herbicides.
A healthy plant not damaged by pests or other environmental factors responds better to improved nutritional conditions. Thus, according to the data of Rotamsted experimental station, the yield of grain of spring wheat damaged by nematodes and fungal diseases at N75 was 1.45 t/ha, and the soil treatment with formalin increased to 3.75 t/ha. Application of N225 without formalin provided a yield of 2.93 t/ha, and in combination with it – 4.49 t/ha.
Fertilizer efficiency depends on the type and yield of predecessors of fertilized crops, on the composition and scheme of alternation of crops in time and space, i.e. on crop rotation. Many crops have the ability to absorb nutrients from hard-to-reach compounds: legumes due to nitrogen fixation can provide their own nitrogen requirements by 50-97%, lupins, buckwheat, mustard have the ability to absorb phosphorus hard-to-reach phosphate soils and fertilizers.
After the mineralization of root and crop residues of these crops, the nutrients contained in them become available to subsequent crops that do not have similar biological characteristics. This is one of the reasons for the better assimilation of nutrients and the greater efficiency of the latter in crop rotations as compared to no-till crops. Cereal-grass-row (fruit-changing) crop rotation is one of the ways to increase nutrient cycling in a particular area and increase the productivity of cultivated crops.
Another reason of increasing efficiency of fertilizers under crops in crop rotations is improvement of phytosanitary condition of crops. The crop rotation creates better conditions for controlling weeds, diseases and plant pests.
According to the data of 86-year experience of the Department of Agriculture of the Moscow Agricultural Academy summarized by A.A. Alferov in 1978-1998, on average crop yields under different fertilization in crop rotations and in the sod-podzolic light loamy soil, the average yields of winter rye under no-tillage and in crop rotations were: without fertilization 1.29 and 2.51 t/ha, with the use of mineral fertilizers 2.33 and 2.97 t/ha, with a combination of mineral fertilizers with manure and lime 2.68 and 3.25 t/ha. Thus, the fertilizing value of crop rotation decreases when using mineral fertilizers, but the phytosanitary role constantly provides a higher efficiency of fertilizers.
The average yield of potato tubers was 8.3 and 9.2 t/ha without fertilizers, 19.1 and 19.1 t/ha using mineral fertilizers, 16.7 and 23.3 t/ha using a combination of mineral fertilizers, manure and lime, respectively. This crop can be cultivated without rotation, but the phytosanitary role of crop rotation manifested itself with a combination of lime, manure and mineral fertilizers maximum yield.
Average barley yields were, respectively, 0.39 and 0.31 t/ha without fertilization, 2.59 and 2.83 t/ha with mineral fertilization and lime, 2.79 and 3.25 t/ha with mineral fertilization, manure and lime. The phytosanitary role of crop rotation in this example is manifested in the increase of the effectiveness of increasing the saturation of fertilizer only against the background of lime.
The average clover hay yield was 1.95 and 3.60 t/ha without fertilizer, 5.55 and 6.66 t/ha with phosphorus-potassium fertilizer and lime, respectively, and 5.85 and 5.99 t/ha with mineral fertilizer, manure and lime combined. This example shows the fertilizing and phytosanitary role of crop rotation and the real ability of clover to meet the need for nitrogen.
As crop agronomy improves under the influence of fertilizers, yields increase both in crop rotations and in perennial crops; on both poor and cultivated soils. Different crops respond differently to fertilizers, cultivation in crop rotations and combinations of these factors.
According to the generalized data of the experiments of the Department of Agriculture of the Moscow Agricultural Academy, the contribution of crop rotation, fertilizers and their combination in the Non-Black Soil Zone to the total increase in yields, respectively, is:
- in winter wheat 57%, 32% and 11%;
- in oats – 56%, 36% and 8%;
- in potatoes 22%, 55% and 23%;
- in beets 10%, 69% and 21%;
- corn 6%, 81%, and 13%.
In cereals, more than 55% of the yield increase is due to crop rotations and only 32-36% to fertilizers, in row crops 55-81% to fertilizers and only 6-22% to crop rotations. This means that row crops should be placed in on-farm crop rotations, it is permissible to practice double cropping and cultivation in the lead fields. This becomes important under conditions of agricultural production intensification.
Under conditions of insufficient moisture, bare fallows in crop rotations improve moisture supply, enhance mineralization of organic matter and facilitate the fight against weeds. Therefore, under crops, followed by a bare fallow, the effectiveness of phosphorus-potassium and organic fertilizers increases, nitrogen – reduced. On seeded fallows efficiency of all fertilizers is usually higher than on bare.
After and one year after perennial grasses efficiency of organic and nitrogen fertilizers decreases, and phosphorus-potassium – increases.
Moisture availability of soils and crops is a factor of fertilizer efficiency. In zones of insufficient moisture and arid climate fertilizers are ineffective, applied in small quantities – up to 20-30 kg/ha a.s. In these conditions phosphate fertilizers are more effective, applied at the time of sowing in doses of 10-20 kg/ha a.s. Only with irrigation efficiency increases significantly, first of all nitrogen, then phosphorus and organic fertilizers.
In the Non-Black Soil Zone there are three regions with different need for hydromelioration:
- region of unstable moisture is represented by leached chernozems, gray forest and podzol soils. Rainfed agriculture is developed here for most crops in combination with irrigated agriculture for vegetable, fodder and other moisture-loving crops. Fertilizer efficiency under irrigation increases considerably here. So, on average for 18 years, according to data of All-Russian Institute of Fertilizers and Agrochemistry, increase of green mass of corn by fertilizers under irrigation increased by 15,6 t/ha, fodder beet – by 20,0 t/ha, buckwheat grain – by 0,35 t/ha.
- The region of sufficient moisture is represented by sod-podzolic soils, on which, first of all, low moisture soils, irrigation in combination with fertilization under vegetable and fodder crops is promising.
- The region of excessive moisture is represented by sod-podzolic soils and peatlands, on which drainage is required to increase fertilizer efficiency and only in some periods irrigation of vegetable and forage crops is applied. Potassium, copper, phosphorus and nitrogen fertilizers are effective on drained peat and mineral soils. Soil drainage system in this region should function if necessary in dry years or periods of short-term droughts, also as an irrigation system.
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.
Sod-podzolic and gray forest soils
Soils of the Non-Black Soil zone are characterized by low natural fertility: acidic reaction, low content of organic matter, low provision with nutrients. On such soils the liming of acidic soils, the maximum use of organic fertilizers, the application of high rates of mineral fertilizers is of great importance.
The need for liming, the amount of applied mineral and organic fertilizers, their distribution between crops is decided taking into account the following factors:
- soil conditions – soil type, granulometric composition, acidity, content of mobile nutrients;
- type of crop rotation – field, forage, specialized, grassland, vegetable;
- availability of organic fertilizers;
- necessary assortment of mineral fertilizers;
- availability of lime fertilizers;
- level of agrotechnics;
- availability of high-yielding varieties;
- levels of planned yields.
Fertilizer systems should provide for growth of crop yields, improvement of the quality of plant products from one rotation to another.
The development of the fertilizer system in the rotation in the Non-Chernozem zone begins with the determination of the place of liming and the dose of lime fertilizers. Liming should precede the application of fertilizers.
The effectiveness of organic fertilizers in the rotation increases with:
- their application under row crops;
- under a cover crop with grasses in rotations with perennial legume-grass, the impact of organic fertilizers will have a better effect on subsequent crops;
- in combination with mineral fertilizers on humus-poor soils of light granulometric composition.
In crop rotations for livestock complexes of industrial type, which accumulate a sufficient amount of litter-free manure, this fertilizer is applied in the main reception and fertilization of perennial grasses. Mineral fertilizers are applied in optimal doses primarily for industrial crops, potatoes, cereals, cultural meadows and pastures. Increasing doses of mineral fertilizers is advisable primarily on soils with adjusted water regime, limestone or not requiring liming, as well as on soils cleared of stones, shrubs, weeds.
The system of fertilization of individual crops in the rotation in the Non-Black Soil Zone includes the main fertilization, pre-sowing and top dressing. Organic fertilizers, lime, phosphorus and potassium fertilizers are applied to the basic fertilizer under autumn plowing. When cultivating spring grain and row crops nitrogen fertilizer is made in spring during cultivation, and for winter crops – in top dressing. When using high rates of nitrogen fertilizer (90-120 kg/ha) on loamy soils, 1/3 of the norm is made under the autumn plowing. Fertilizer applied in spring also refers to the basic fertilizer.
It is especially important to determine rates of nitrogen fertilizers for winter and spring crops, under the cover of which leguminous grasses are sown. Strong grass stand of cereals and high grain yields of the cover crop worsen the conditions of water and nutrient regimes of grasses, as well as solar insolation, which weakens their growth, leads to thinning and reduction of yields. In the Non-Black Soil Zone high rates of nitrogen more than 90 kg/ha in a single application or intake are inexpedient. Fractional application increases the coefficient of utilization of nitrogen fertilizers, their efficiency and improves the quality of agricultural products.
On sandy and sandy loam soils nitrogen fertilizers for spring cereals and row crops are applied only in spring. For winter crops on all types of soils, 1/3 of nitrogen fertilizer rate (30-40 kg / ha) is applied before sowing. When winter crops are placed in the rotation after leguminous crops and leguminous grasses, applying nitrogen before sowing often does not lead to positive results.
If the farm has a sufficient amount of phosphorus-potassium fertilizers in the fertilizer system can provide application under perennial grasses “in reserve”, ie for 3-4 years, as phosphorus and potassium are well fixed in the soil and with a surface application of fertilizer is less effective. This is especially true for phosphate meal.
Pre-sowing fertilization is provided for the introduction of granulated superphosphate, ammophos, nitrophos and other complex fertilizers into the rows when sowing spring and winter crops. On well fertilized soils, the effectiveness of this technique is reduced, but remains advisable, as fertilizer, made at sowing, contribute to good sprouts, strengthening of tillering and overwintering of winter crops.
Top dressing with nitrogen fertilizers is provided first of all for winter crops, which after the overwintering come out weakened and need nitrogen in the first place. Topping with phosphorus-potassium fertilizers is carried out when the crop received an insufficient amount of these fertilizers at the basic application. Nitrogen fertilization of perennial grasses with a large share of legumes is inexpedient. As the share of legumes in grass mixture decreases below 50%, which happens in the second year of grasses use, spring fertilizing with nitrogen N40-60 is provided.
In rotations with flax, a full mineral fertilizer is applied to this crop, but the rate of nitrogen is much lower than that of phosphorus and potassium. Excessive nitrogen leads to lodging of flax and worsens the quality of flax fiber. It is especially important when flax is placed after high-yield perennial grasses with clover predominance. In this case the rate of nitrogen should not be more than 30 kg/ha. After other predecessors, including one year after grasses, the nitrogen dose is not more than 40-60 kg/ha. On cultivated soils where there is a risk of lodging flax, sowing flax after clover with a hay yield of 5 t/ha will not provide a good quality crop. In this case, flax should be sown after one year or to other predecessors.
In crop rotations on sandy and sandy loam soils, a large proportion is sowing leguminous crops: lupine for fodder and grain, green manure, as well as seradella. These plants have good nitrogen-fixing ability and need phosphorus-potassium fertilizer. On the effectiveness of macrofertilizer, especially at higher doses, affects the provision of micronutrients.
The fertilization system of crops grown on the peat-bog soils with high productivity, based on the use of soil nitrogen reserves and the introduction of phosphorus and potash fertilizers. Nitrogen fertilizers are used to fertilize winter cereals and perennial grasses, especially on the less powerful poorly cultivated peat-bog soils.
Zone of black earth (chernozems) and chestnut soils
The zone of chernozems and chestnut soils occupies a vast territory of Russia (Central Black Earth zone, North Caucasus, Volga region), Ukraine and Kazakhstan (Northern, Southern and South-Eastern Kazakhstan). When considering the scientific basis of fertilizer systems this zone is divided into two parts: forest-steppe and steppe. These sub-zones differ in soil and climatic conditions, specialization of crop production, provision with mineral fertilizers.
Due to the shortage of mineral fertilizers in the forest-steppe areas, they are applied mainly under technical crops, potatoes, forage crops and partially under grain crops. The balance of nutrients in agriculture is characterized by a high deficit, which leads to a decrease in potential fertility, losses of organic matter, deterioration of water-physical properties of soil.
When distributing fertilizers in crop rotation optimal rates are applied to sugar beets, sunflowers, potatoes, corn for grain and silage, winter crops, fodder crops under irrigation. Spring cereals, leguminous crops and cereals are cultivated on fertilized preceding crops at the expense of fertilizer aftereffects. Under these crops directly applied pre-sowing phosphate fertilizer (P10-15).
In the year of application, plants use 20-25% of phosphorus, 50-60% of nitrogen and potassium from mineral fertilizers; 20-30% of nitrogen, 30-40% of phosphorus, 60-70% of potassium from manure.
Taking into account the after-effect of manure, which in this subzone is stronger than in the Non-Black Soil Zone, in the 9-11-field crop rotations, it is applied twice per rotation, in the 6-7-field – once. More fractional application of manure per rotation does not give advantages. The best place for the application of manure in the rotation is the precursor of winter crops and directly under the winter crops, if the crop is harvested early. Good results are obtained by applying manure for potatoes, vegetable crops, corn for grain and silage.
In forest-steppe field crop rotations, manure is applied in rates: under winter wheat and rye – 20-30 t/ha; under corn, sugar beets and potatoes – 30-40 t/ha. In areas with sufficient moisture, peat and other composts are used in addition to manure.
Soil-protective crop rotations on slopes allow for cultivation of perennial grasses for at least 3-4 years; therefore, in order to guarantee a high yield of grasses, increased doses of manure, 40-60 t/ha, are applied 1-2 years before sowing winter wheat or corn.
In the forest-steppe areas of the Black Earth region the role of the main fertilizer increases. In this reception make at least 2/3 of the annual dose of fertilizer under autumn plowing in the non-drying layers of soil. In areas of sufficient and excessive moisture nitrogen fertilizer for autumn plowing is not made, they are used in the spring for pre-sowing cultivation and top dressing.
In areas bordering Polesie, on soils with light granulometric composition and in areas with a close groundwater table under the autumn plowing all types of nitrate is not made to prevent leaching of nitrogen in the winter in the lower layers. In this subzone under the plowing is preferable to make ammonium forms of fertilizers.
Phosphorus-potassium fertilizers in all areas of the forest-steppe is preferable to make under the plowing. Phosphate flour and phosphate slag is made only under the plowing and in the first place on acidic soils, such as gray forest, podzolized and leached chernozems. Crop rotation crops that have not received basic fertilizer, sow with pre-sowing application of superphosphate or compound fertilizer.
Crop feeding is carried out only with nitrogen fertilizers in the recommended doses and at the optimum time for the crop. Nitrogen fertilizers are especially effective for winter crops in fallow and non-fallow preceding crops.
In the forest-steppe areas there is a wide variety of soils: from gray forest and podzolized black earth in the north to the typical carbonate in the south. In the northern part there is more moisture, so nitrates accumulate less. In addition, they are more washed out in the winter, so in these soils in the fertilizer system is dominated by nitrogen, which is often in the first minimum.
Carbonate and typical chernozems of this subzone have good water-physical properties and have an increased nitrification capacity. Nitrates formed during summer period, as a rule, are not washed out from root layer. Carbonate soils makes reserves of phosphorus less mobile, so phosphorus fertilizers are effective. Provision with potassium of these soils is good enough, but potassium fertilizers in the northern forest-steppe are effective.
On carbonate chernozems because of their slightly alkaline reaction more effective physiologically acidic fertilizers. In the system of fertilizing crops for podzolized soils and highly leached chernozems once a rotation rotation provide lime treatment. The best place to apply lime fertilizer is a field where sugar beets, winter after fallow or leguminous crops. Defecation mud, a waste product of sugar beet production, is best suited as liming material.
On saline soils once every 8-10 years, gypsum is applied under sugar beet or winter wheat, preceding it or peas.
In forest-steppe areas the effect of microfertilizers, such as boron on sugar beets and molybdenum on legumes and legume crops is often manifested.
The soils of the steppe regions are also diverse, ranging from typical and common chernozems in the north to southern and Azov chernozems in the south. Carbonate soils are often found in these areas. Chestnut soils are common in the eastern areas, where the steppe transitions to dry steppe. Steppe areas are located in the south of the Central Black Earth zone, in the north of the North Caucasus and the Volga region, in Kazakhstan – Northern, Southern and Southeastern regions.
In the fertilization system of crop rotations should be dominated by the basic fertilizer, which is introduced in autumn under the plowing. This method eliminates the possibility of washing away and wind drift of fertilizers, as well as gaseous losses of nitrogen. In this case, the fertilizer is placed in the wetter soil layers. A single application of fertilizer in autumn is often more effective than applying the same rate in several applications.
In the steppe regions moisture availability is a factor limiting the yield and fertilizer efficiency, so all measures aimed at accumulation and preservation of soil moisture contribute to improving the effectiveness of fertilizers. In turn, fertilizers contribute to a more economical use of moisture to create yields. Water consumption for the creation of a unit of dry matter on a fertilized background decreases by 15-20%.
In steppe areas, phosphorus is often at a minimum. Phosphorus starvation of plants is a factor limiting the yield of crops. Improvement of soil phosphorus supply is achieved by applying phosphorus fertilizers. The maximum yield is achieved with the application of nitrogen, potassium and phosphorus, with the predominance of the latter.
The main method of applying fertilizers is to apply them in autumn under autumn plowing. In this method up to 85-90% of the annual rate of fertilizers for the crop is applied. The rest, mainly phosphorus, is applied in the rows during sowing. Fertilizers are ineffective, with the exception of nitrogen top dressing of winter crops.
When developing a system of fertilizers in the rotation on rainfed soils in determining the location of the main fertilizer take into account:
- application of fertilizers in fractional rates under most crops of the rotation is not always rational;
- high after-effect, especially of phosphorus and potassium fertilizers: increases in yield due to after-effect sometimes exceeds the effect of the direct action.
In steppe areas the filling fertilizer of rotation with short rotation (5-6-field) is applied 1-2 times. In 9-11-field steam-tilled and grain-tilled crop rotations the basic fertilizer is applied 3-4 times per rotation.
Manure is used primarily as a basic fertilizer, which is better to apply in the black fallow and corn. It is introduced in autumn under autumn plowing or when plowing fallow. Mineral fertilizers in the main reception in the 10-12-field crop rotation make a bare and seeded fallow under winter crops, corn and spring wheat. All other crops of the rotation use the effect of the main fertilizer and receive in the rows at sowing granulated superphosphate or complex fertilizer.
In the conditions of Northern Kazakhstan, with a high content of soil potassium, the fertilizer system is reduced to the development of techniques and methods of optimization of phosphorus and nitrogen nutrition of crops.
The high deficit of phosphorus in the soils of the subzone determines the high efficiency of phosphorus fertilizers for all crops. For example, phosphorus applied to grain crops, depending on the doses and deficit provided a yield increase from 250-500 to 800-900 kg/ha.
On chernozems in the forest-steppe and steppe zones with precipitation of 350-370 mm (l/m2) the pre-sowing application is equal to the basic or even exceeds it. However, in the dry-steppe zone on dark chestnut soils the main application of phosphorus fertilizers in a fallow is 1.5-2 times more effective than the annual pre-sowing. In the dry-steppe zone, a stable increase by seeding is provided only on the first crop after the fallow, where there is enough nitrogen and better moisture conditions.
In fallow fields, in the presence of moisture and under the influence of treatments accumulates a sufficient amount of mineral nitrate nitrogen. The content of mobile forms of phosphorus changes insignificantly. This explains the high efficiency of phosphorus fertilizers on fallow. Fallow is the best place in the crop rotation for the application of phosphorus fertilizers.
They have the greatest effect when applied to the moist soil layer, to a depth of 16-20 cm, but not less than 12 cm, in a zone of stable moisture. In the absence of special machines, fertilizers are made by grain-fertilizer seeders on the cultivated to a depth of 14-16 cm fallow. Surface application of phosphate fertilizer reduces their effectiveness by 2-3 times.
In cereal-grass-row without fallow crop rotations phosphate fertilizers made under the leading crop rotation. In rotations with perennial grasses – under the plowing of perennial grasses. This is the only case when the fertilizer can be applied superficially.
Given the long after-effect of phosphate fertilizers, they are made in a fallow field in a zone of stable moisture – to a depth of 12-20 cm once every 4-5 years, providing a rotation of the rotation.
With the local introduction of optimal doses of phosphate fertilizers recoupment of 1 kg d.a.s. for a rotation of 4-5-field crop rotation is 10-15 kg of grain in favorable years – up to 20 kg.
According to long-term studies of nitrogen regime of soils and nitrogen fertilizer efficiency in the conditions of Northern Kazakhstan (Chernenok V.G., 1993, 1997), the main factors determining the effectiveness of nitrogen fertilizers are: the content in the soil of nitrate nitrogen, mobile phosphorus, their ratio and moisture conditions. Nitrogen fertilizers can increase yields for 2 years.
The predominant mineral form of nitrogen in the soils of Northern Kazakhstan is nitrate. The most favorable conditions for nitrification are in the fallow field, where the nitrate content can increase by 2-3 times, providing a high level of nitrogen nutrition of the first crop after fallow. However, in the case of extremely dry conditions during fallow when there is less than 200 mm of rainfall per year, the nitrification process is suppressed. After such years of unfavorable nitrogen conditions, this affects the first crop after fallow. As the crops [in the rotation] are moved away from the fallow, the nitrate content decreases by 2-4 times.
Phosphate fertilizers are effective with a good level of nitrogen nutrition, that is, on the first crop after fallow, and nitrogen fertilizers – on crops more distant from the fallow.
On the southern carbonate chernozem according to the Kazakh Research Institute of Grain Farming (KazNIIZH) on the second crop after fallow increased yields of cereal crops from nitrogen fertilizers is noted in 22% of cases, on the third – 37%, on the fourth – 60%, on the fifth – 82%.
However, in extremely dry years with precipitation of less than 200 mm per year, nitrogen fertilizers are not advisable, because they will not give effect regardless of the content of nitrogen due to an acute shortage of moisture.
The effectiveness of nitrogen fertilizers depends on the timing of application, which is associated with moisture conditions. In the Black Earth zone with more than 320 mm of precipitation per year, the fall application of ammonium nitrate is inferior to the spring one in terms of efficiency. In the chestnut soil zone with annual precipitation of less than 300 mm, the timing of ammonium nitrate application had no effect on their effectiveness, but in years with rainy autumn the spring application was more effective, and in years with dry spring the autumn application was less effective. The best form of nitrogen fertilizer for spring wheat when applied under pre-sowing cultivation is urea, for barley – ammonium sulfate.
The effectiveness of nitrogen fertilizers increases with increasing phosphorus content to the optimal level, for spring wheat is 35 mg P2O5 /kg soil. With further saturation of soils with phosphorus effect decreases, which is associated with a violation of the relationship between the elements of nutrition.
From nitrogen fertilizers for soils of steppe areas urea, ammonium nitrate, ammonium sulfate are recommended. Physiologically alkaline nitrogen fertilizers increasing soil alkalization are unacceptable.
For non-fallow preceding crops and in cereal-grass-row without fallow crop rotations more effective use of complex nitrogen-phosphorus fertilizers (nitrophos, nitroammophos) at the basic, rowwise application and in top dressing. Ammophos on the efficiency is equal to double superphosphate, but inferior in economic efficiency.
From potassium fertilizers, it is better to apply potassium chloride and potassium sulfate.
Organic fertilizers are applied primarily in the fields with low fertility. Approximate doses of manure for cereals – 20-30 t/ha, row crops – 30-40 t/ha, vegetables – 40-50 t/ha.
Cereal straw can be used as organic fertilizer. In terms of its impact on soil fertility, 1 ton of straw is equivalent to 3-3.5 tons of manure. According to KazNIIZH data, at a yield of 1.5-2.0 t/ha of grain the straw ensures a deficit-free balance of humus in the 4-6-field grain-fallow crop rotations.
Fertilization system of crop rotations under irrigation
The fertilization system of crop rotations under irrigation is built taking into account the specialization, granulometric composition of soils, the availability of nutrients, groundwater table, moisture regime. At the same time methods and timing of applications are used which increase the coefficient of utilization of nutrients and prevent loss to the environment.
When irrigated, plants on all types of soils need nitrogen the most. Application of nitrogen fertilizer on the background of phosphorus or phosphorus and potassium increases the yield of grain of winter and spring wheat and green mass of maize by 1.5-2 times. The effectiveness of phosphate fertilizers is lower than that of nitrogen fertilizers, and occurs mainly with their joint application. Increase in yield of cereals and forage crops from phosphate fertilizers on irrigated lands is usually 20-30%, depending on the provision of phosphorus soils. Potassium fertilizers on irrigated lands are ineffective when applied to wheat, corn and alfalfa. In recent years there has been an increase in the effectiveness of potash fertilizers.
The nitrogen problem is solved comprehensively: through a combination of mineral and organic fertilizers, expansion of alfalfa crops on irrigated land. Phosphorus deficit is covered by mineral phosphorus fertilizers. Mineral fertilizers per hectare of irrigated arable land are applied at full demand. At a high level of agrotechnics the greatest recoupment of fertilizers is observed.
Under irrigation conditions the timing of fertilizer application is important. Phosphate and potash fertilizers under all crops are made in autumn under the main tillage. Nitrogen fertilizer on loamy and clay soils with deep groundwater is made in autumn for plowing or spring for cultivation. On sandy and sandy loam well-drained soils, nitrogen fertilizer is applied in spring before sowing. It is important to choose the right form of nitrogen fertilizer. The best under irrigation conditions are urea, ammonium sulfate, carbophosks. Nitrate forms are undesirable because they significantly migrate through the soil profile.
During vegetation, winter wheat crops are fertilized with nitrogen fertilizers (in late autumn or early spring superficially), corn (in the phase of the 4th-5th leaves by cultivator-fertilizers), alfalfa is fertilized with phosphate fertilizers (superficially in early spring). Feeding with urea or ammonium nitrate during earing to the end of flowering is effective to improve grain quality of spring and winter wheat.
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific and Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.
The maximum increase in yields of all crops from organic and mineral fertilizers, both in their separate and combined application, are achieved on the poorest soils. In the transition to more fertile and cultivated soils as limiting factors of growth and development of plants to a greater extent appear climatic and other conditions, so the effectiveness of fertilizers is most often reduced.
Such a decrease is observed in the transition from sod-heavy-podzolic, to medium and weak-podzolic, then from light to dark gray forest, then from podzolic and leached to common and southern black soils, then from dark to light chestnut soils.
Within one type and subtype, fertilizer efficiency is determined by the granulometric composition of the soil. In general, there is a pattern: the poorer the soil of lighter granulometric composition, the greater the relative yield gains from fertilizers. Although absolute gains in t/ha on more fertile soils are often higher than on less fertile ones.
Individual types of fertilizers also show different effectiveness: nitrogen fertilizers are more effective on sod-podzolic, gray forest soils, podzolized and leached chernozems, and on all irrigated soils. For podzolic loamy soils the following average security of crop yields by individual elements is typical: nitrogen – 38% of maximum productivity, phosphorus – 76% of maximum productivity, potassium – 82% of maximum productivity. With the improvement of moisture availability efficiency of nitrogen fertilizers increases on all types and varieties of soils.
Phosphate fertilizers are more effective in areas with insufficient moisture and arid climate on southern, ordinary chernozems, chestnut and brown soils, on poorly cultivated soils of other types. For example, on sod-podzolic uncultivated differences (1-2 class) they are more effective than nitrogen fertilizers.
Potassium fertilizers are more effective on peaty, then on sod-podzolic and gray forest soils. On gray soils, chernozems and chestnut soils, their effectiveness is reduced, often absent.
By granulometric composition on light soils of all types, the effectiveness of nitrogen, potassium and micro fertilizers increases on heavy – phosphorus. In the first case, it is associated with an easier leachability of elements in the second – with a greater binding of phosphorus in hard-to-reach compounds. If heavy soils are represented by minerals capable of fixing potassium and ammonium, potassium and nitrogen fertilizers are also effective on them.
The effectiveness of fertilizers on soils with an acid or alkaline environment depends on the crops being cultivated. Chemical reclamation should always precede the application of fertilizers. The effectiveness of all types of fertilizers and under all crops increases with the neutralization of acidic and alkaline soils, reaching a maximum at the optimal reaction for the cultivated crops. Thus, according to the generalized data of the experiments with barley on sod-podzolic soils the payback of 1 kg of fertilizer nitrogen by grain yield increase with pH of the salt extract less than 5 was 7.6-8.4 kg, with pH salt extract above 5.6 – 18.6-20.2 kg.
The effectiveness of each type of fertilizer decreases with increasing soil sufficiency of the respective elements available for plants and often disappears at high or very high (5-6th class) sufficiency.
According to the generalized L.M. Derzhavin (1992) data of experiments of agrochemical service (CINAO) with winter wheat on sod-podzolic medium-supplied potassium (100 mg/kg) soils, grain yield increases from 60 kg/ha P2O5 were: With a mobile phosphorus content of 50 mg/kg soil – 0.43 t/ha, 100 mg/kg – 0.36 t/ha and 150 mg/kg – 0.28 t/ha, and on leached chernozem – respectively 0.94 t/ha; 0.51 t/ha and 0.08 t/ha. From 60 kg/ha of K2O the yield increases of winter wheat were: on sod-podzolic soils with exchange potassium content of 50 mg/kg – 0.64 t/ha, 100 mg/kg – 0.33 t/ha and 150 mg/kg – 0.02 t/ha, and on medium phosphorus (125 mg/kg) dark gray forest soil and podzolic chernozem with exchange potassium content of 75 mg/kg – 0.49 t/ha, 125 mg/kg – 0.25 t/ha and 175 mg/kg – 0.02 t/ha.
Similar patterns of effectiveness of all types of mineral fertilizers are typical for all crops on any soils, but manifested with different intensity. Fertilizers and ameliorants simultaneously change agrochemical indicators and other properties of soils. For example, according to long-term stationary experience (since 1912) of the Department of Farming of the Moscow Agricultural Academy named after K.A. Timiryazev on sod-podzolic medium-loamy soils in the variant without fertilizers average potato yield for 1955-1972 years was 6.7 t/ha, in 1973, when applying N100P150K120 – 16.0 t/ha, while the soil had a pH of 3.83; content of humus 1.45%, mobile phosphorus and exchangeable potassium (by Kirsanov), respectively, 19 mg/kg and 41 mg/kg. In the variant of systematic application of fertilizers, the average potato yield in 1955-1972 was 15.4 t/ha, in 1973, at the same dose – 24.7 t/ha; soil pH 3.92, the content of humus 1.61%, mobile phosphorus and potassium, respectively, 100 mg/kg and 133 mg/kg. In the variant with the systematic use of mineral fertilizers, manure and periodic liming, the average potato yield in 1955-1972 was 19.1 t/ha; in 1973, with the same dose of fertilizers – 32.1 t/ha, the soil was most fertile – pH 5.67, humus content 2.07%, mobile phosphorus and potassium respectively 128 mg/kg and 207 mg/kg. Similar results were obtained with potatoes and other crops in other long-term experiments of different countries.
The mobile forms of nutrients accumulated by fertilizers and ameliorants are distributed over time throughout the root layer and prove to be most necessary under adverse conditions, when the application of fresh doses of fertilizers even in high doses with inevitable localization may be less effective.
Systematic agrochemical examination of soils carried out since 1965 in all farms, including homestead and garden plots, revealed the heterogeneity of agrochemical indicators within not only types, subtypes and varieties of soils, but also one field and field plot. This fact marked the need to take into account the existing differences in the classification of soils according to these indicators and in determining and adjusting the doses of fertilizers.
On the basis of relative indicators (classes, groups) of soils we correct the recommended doses of fertilizers for crops, in the absence of recommendations – we introduce correction factors. Correction factors to the doses must ensure that the planned yield of crops of good quality, while regulating the provision of soils with nutrients. When the average security of a particular crop, for example, for cereals, legumes and grasses – 3 class, for row crops – 4 class, for vegetables – 5 class, the correction factor to the dose is 1. When cultivating crops on soils poorer than the middle class, the correction factor is increased (more than 1), on more fertile than the middle class – less than 1. When changing by one class the dose of fertilizer on average for all crops should change by 20-30%, i.e. for soil poorer than average by one class the correction factor should be 1.2-1.3, by two classes – 1.4-1.6, etc., for soil richer than average by one class – 0.8-0.7, by two classes – 0.6-0.4, etc.
According to absolute indices the content of available forms of nutritious elements in soil is determined by the results of field experiments their part assimilated by the crop. This part is called the coefficient of utilization of soil nutrient element (CUE), determined by the formula:
where R0 – economic removal in the variant without fertilizers, kg/ha; S – stocks of mobile forms of the element, kg/ha; 100 – recalculation in percent.
Table. Yield and economic removal of nutrients by potatoes at different fertilization on sod-podzolic loamy sand soil (Vergey)
Example. Determination of potato CUE on sod-medium podzolic loamy sand soil with pH 4.8, Hg 3.5 and S 3 mg⋅eq/100 g, V 46.1%, phosphorus and potassium security according to Kirsanov 67 mg/kg and 102 mg/kg, hydrolysable nitrogen 50 mg/kg, humus content 1.5%. The arable soil layer (at its mass of 3 mln kg) contains:
- 201 (67⋅3) kg/ha P2O5,
- 306 (102⋅3) kg/ha K2O,
- 150 (50⋅3) kg/ha N.
Potatoes in the variant without fertilizer with an economic yield of 6.2 t/ha removal 94 kg N, 27 kg/ha P2O5 and 127 kg/ha K2O, therefore:
- КИП(N) = 94⋅100/150 = 63%;
- КИП(P2O5) = 27⋅100/201 = 13%;
- КИП(K2O) = 127⋅100/306 = 41%.
At the same time, you can determine the CUE in paired combinations where the appropriate fertilizer was not applied:
- by PK – CUE(N) = 110⋅100/150 = 73%;
- by NK – CUE(P2O5) = 37⋅100/201 = 18,1%;
- by NP – CUE(K2O) = 201⋅100/306 = 66%.
From the above calculations, it follows that the coefficients of use of nutrients change significantly under the influence of fertilizers, and determine them for all crops only in variants without fertilizers.
Generalization L.M. Derzhavin (1992) experimental data CINAO showed that even at the same initial provision, the CUE of phosphorus and potassium varies greatly: for winter wheat 63% and 55%, winter rye 78% and 89%, spring wheat 52% and 56%, spring barley 55% and 95%, potatoes 63% and 85%, sugar beet 71% and 41%, couch flax 64% and 86%.
In the transition from low to high provision of soils with movable elements, the CUE of phosphorus and potassium decreased even more significantly: for winter wheat 4.6-5.7 and 2.7-3.4 times, winter rye 3.7-4.5 and 3.9 times, spring wheat 1.7-3.2 and 2.7-2.8 times, barley 3, 9-5.1 and 1.8-2.6 times, potatoes 3.8-4.4 and 2.9 times, sugar beet 4.9-6.4 and 2.3-2.6 times, flax 6.0 and 2.0-2.3 times.
Especially strong CUE of elements varies under the influence of weather conditions. According to the data summarized by the Department of Agrochemistry of the Moscow Agricultural Academy, the coefficients of mobile phosphorus use by crops depending on weather and agrotechnical conditions differ by 10-15 times, potassium – by 10 times.
Therefore, to correct and determine the doses of fertilizers on the results of the provision of soils with mobile forms of nutrients is better to use not absolute but relative indicators, that is classes and correction factors, as the above variability of absolute indicators leads not to increase but to decrease the effectiveness of fertilizers.
Climatic and weather conditions are often a determining factor in fertilizer efficiency.
The higher the light and moisture supply, the more carbohydrates are synthesized and the more nitrogen the plants can assimilate. Light affects plant nutrition not only through photosynthesis, but also through transpiration. As humidity increases, plant tolerance to increasing concentrations of nutrient solutions increases.
Soil temperature speeds transformation of nutrients and their absorption by plants. At 8-10 °C, the intake, movement and inclusion of nitrogen and phosphorus into the metabolism decreases, and at 5-6 °C the root consumption of nutrients is sharply reduced. At temperatures of 10-25 °C, the mobilization and absorption of soil nutrients and fertilizers by plants increases.
The optimum daytime temperature (23-25 °C) corresponds to 14-16 °C average daily temperatures. In the Non-Black Soil Zone, according to A.P. Fedoseyev, the average monthly summer temperature above 18.1 °C reduces the effectiveness of fertilizers, in the Black Soil Zone the increase of air temperature in May-July by 1 °C above the long-term norm reduces the increase of grain yields from fertilizers at doses of 120-180 kg/ha a.m. by 0.02 t/ha on average.
Increasing humidity deficit by 1 hPa in May reduces fertilizer efficiency by 40 kg/ha on average, in July by 4 kg/ha.
Reducing the annual norm of precipitation from north to south by 100 mm (100 l/m2) in the European part of Russia reduces the efficiency of average doses of fertilizers on average by 0.11 t/ha for all cereal crops and by 0.19 t/ha for winter crops. Reduction of moisture reserves in soil by 10 mm during vegetation of cereal crops reduces yield increases from fertilizers by 10-20 kg/ha on average. If the ratio of precipitation to evapotranspiration is taken as 100%, then each 10% increase in aridity reduces the fertilizer effect by 15%.
When moisture content increases to 90% of the smallest moisture content on soils with volumetric mass of 1.2-1.3 g/cm3 and to 80% on soils with 1.5-1.6 g/cm3 fertilizer efficiency increases. Further moistening of soils to 100-120% of the smallest moisture capacity on the first soils gradually, and on the second sharply reduces the effectiveness.
Excess moisture in soils of the Non-Black Soil Zone and in irrigated areas causes intra-soil and surface water runoff, which leads to leaching of nutrients. Calcium, sulfur, magnesium, nitrogen, carbon, sodium and potassium are leached from fertilizers and soils. The least leached is phosphorus. Maximum leaching occurs during spring floods and after harvesting in the fall.
On loamy and sandy loam soils of the Non-Black Soil area at saturation with fertilizers (N60P60K60) with precipitation washed out up to 50 kg/ha (on loamy) and 70-120 kg/ha (sandy loam) of calcium, 3-7 kg/ha and 10-15 kg/ha of magnesium, 14 kg/ha and 25 kg/ha of sulfur, 7 kg/ha and 10-12 kg/ha of potassium, 1-6 kg/ha and 14-18 kg/ha of nitrogen respectively on loamy and sandy loam soils.
The efficiency of average rates of mineral fertilizers (120-180 kg/ha a.s.) depending on moisture conditions in summer months can vary almost 2 times.
Table. Average NPK efficiency on soils of the Non-Black Soil zone depending on wetting conditions in May-July (summarized by Fedoseyev)
Fertilizer efficiency on loamy soils in years with insufficient or excessive summer precipitation decreases, and more significantly with insufficient precipitation. On light soils with excess of precipitation under wheat and spring crops efficiency remains high, and under rye – decreases.
According to the long experience of the Department of Agriculture of the Moscow Agricultural Academy, in years with dry June, with rainfall below 50 mm and temperature above 18 °C, normally moist June (50-90 mm and 16-18 °C) and wet (over 90 mm, temperature below 16 °C), the saturation of the crop rotation fertilizer (N50P75K60) paid 100 kg a. в. of fertilizers was: 0.35 t/ha winter rye grain; 0.44 t/ha and 0.75 t/ha; oat grain 0.17 t/ha, 0.27 t/ha and 0.46 t/ha; potato tubers 4.3 t/ha, 6.3 t/ha and 7.6 t/ha; clover hay 1.4 t/ha, 1.6 t/ha and 2.9 t/ha; flax straw 0.16 t/ha, 0.72 t/ha and 0.92 t/ha.
The efficiency of mineral fertilizers in years with dry June decreased on average by 36% (especially strongly under linen), and with wet June increased by 52% (especially under clover) compared with normally moist June. The combination of the same doses of mineral fertilizers with manure (10 t/ha) mitigated the negative effect of the lack of moisture in June; the efficiency of mineral fertilizers decreased by 27% on average.
On average in the Non-Black Soil zone the increase of grain yield from mineral fertilizers is 0.6 t/ha with fluctuations due to weather conditions ±40%, in the Central Black Soil zone – respectively, 0.52 t/ha and ±44%.
Scientifically justified use of fertilizers weakens the negative impact of adverse weather conditions (low temperatures, frosts) on crop productivity.
According to the data of 40 experiments summarized by A.P. Fedoseyev the number of winter rye and wheat plants which died during overwintering decreased from 42 (without fertilizers) to 27%; when combining phosphorous-potassium and optimal doses of nitrogen fertilizers before sowing the death of winter plants decreased to 18%.
The relationship of fertilizer efficiency with meteorological factors is characterized by correlation coefficients.
Table. Correlation coefficients between the effectiveness of average rates of mineral fertilizers and meteorological factors Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry / Edited by B.A. Yagodin. - Moscow: Kolos, 2002. - 584 p.: ill.
|Central Black Earth|
Correlation coefficients developed by A.P. Fedoseyev (Institute of Experimental Meteorology) and regression equations to estimate fertilizer efficiency from meteorological factors show that weather-climatic conditions explain 25-60% of fertilizer efficiency variations in the Non-Black Earth zone and 35-70% in the Central Black Earth zone.
When determining the optimal and maximum doses of fertilizers it is necessary to be guided by the average for many years meteorological data of specific territories and annually adjust them to the forecast of the coming year. With increasing saturation of crops with fertilizers and the growth of crop productivity, the variation of yields depending on the meteorological conditions of a particular year in absolute values (t/ha) increases, and in relative (% to average) – decreases.
Yagodin B.A., Zhukov Y.P., Kobzarenko V.I. Agrochemistry/Under ed. B.A. Yagodin. – M.: Kolos, 2002. – 584 p.: ill.
Fertilization system – scientifically proven use of fertilizers and ameliorants in the rotation, taking into account the biological needs of crops under the actual soil fertility and opportunities for agricultural enterprise, to maximize yields with high quality and simultaneously regulate the cultivation of soils in specific natural and climatic conditions.
Concept of the fertilization system
Fertilizers, depending on the types, rates, timing and methods of application, their ratios and soil and climatic conditions have different effects and aftereffects. They are most fully used by crops in crop rotations in a particular rotation, due to the structure of cultivated areas. This necessitates the transition from the fertilization of individual crops to a fully justified system of fertilization of crop rotation.
The scheme of the system of fertilizers of crop rotation or agrocenosis is developed and used for a complete rotation of the crop rotation on the basis of the average 5-10-year supply of fertilizers to enterprises and the state of fertility of the fields of the rotation with the definition of types, doses, ratios and total need in kg/ha of active substances, as well as the balance of nutrients.
Doses and ratios of fertilizers and ameliorants of fertilization system scheme are annually adjusted in the plans of fertilizer application, taking into account the placement of crops and soil fertility of these fields, weather conditions and the provision of fertilizers.
Based on the annual plan make a calendar plan for the acquisition, accumulation and use of fertilizers, indicating the amounts, types for the entire fertilized area of the rotation or the entire farm. This allows to define areas of warehouses and storages for agrochemical agents, sequence of acquisition of quantities and types and, accordingly, to manage material and technical resources more effectively.
When implementing annual plans for the application of fertilizers, doses before sowing according to the results of soil diagnostics, as well as when fertilizing crops according to the results of plant diagnostics, are again adjusted.
Development of fertilizer system that meets the natural and organizational and economic conditions requires expert knowledge and practical skills. The following documents are needed to draw up a plan for the application of fertilizers:
- organizational and economic plan reflecting crop rotations;
- soil maps and agrochemical cartograms;
- data on actual yields for the last 5 years;
- norms of application of organic and mineral fertilizers;
- field history book.
To develop a fertilizer system it is also necessary to have information on the type of soil water regime, relief, susceptibility of soils to water and wind erosion, development of animal husbandry, possibilities for accumulation and application of all types of local fertilizers, financial resources, technical equipment for fertilizer application, availability of storage facilities.
Purposes and objectives of the fertilization system
The purpose of the fertilization system is to ensure the highest possible agronomic and economic efficiency on the condition of minimizing the negative impact on the environment with the available natural and economic resources of the enterprise.
The objectives of the fertilizer system in the agrocenosis (or farm) are:
- increasing the productivity of cultivated crops and improving the quality of products with the growth of fertilization of crops to optimal levels;
- elimination of the differences in fertility of individual fields of each crop rotation at any provision with fertilizers and (or) increasing of soil fertility of the fields to the optimum level;
- increase of return on unit of fertilizers by crop yield increase, i.e. increase of economic efficiency of fertilizers at any provision with them;
- obtaining of certified crops production with constant monitoring of agrochemical indicators of soil fertility;
- Increase of labor productivity, organizational and economic and managerial activities;
- continuous compliance with the requirements of environmental protection and sanitary and hygienic legislation.
The degree of achieving the goal and objectives varies with the biological characteristics of crops, soil and climatic and agrotechnical conditions, the amount and quality of fertilizers used.
Scientific fertilization system
The scientific system of fertilization can be divided into:
- Scientific and organizational system of fertilizer use in the farm.
- System of fertilizer use in crop rotation as a part of scientific farming system.
- System of fertilizing individual crops in the rotation, based on the use of optimal rates, forms, timing and methods of fertilizing.
All these components are interrelated.
Fertilization system on the farm
Fertilization system in the farm is a complex of agronomic, organizational and economic measures for the rational use of mineral and organic fertilizers, as well as chemical ameliorants to optimize soil fertility, increase crop productivity, improve the quality of crop production, increase labor productivity in agriculture. It is the most important condition for the intensification of agricultural production.
The fertilizer system in the farm includes:
- availability of warehouses for storing mineral fertilizers with the possibility of mechanization of technological operations;
- accumulation and storage of organic fertilizers;
- organization of vehicles for transportation of fertilizers;
- availability of machinery for application of mineral and organic fertilizers;
- methods of chemical reclamation of acidic and saline soils.
The objectives of the fertilizer system in the farm are:
- obtaining high and stable yields with good quality products;
- reproduction of soil fertility;
- realization of ecological functions of fertilizers in agrocenosis;
- increasing economic efficiency of fertilizers and labor productivity;
- reducing the cost of crop production;
- gaining maximum profit.
Fertilization system is a planned organization of a set of measures related to the use of fertilizers.
Fertilizer system in the farm is to develop and implement organizational, economic and economic measures related to production, procurement, purchase, transportation and storage of fertilizers. Includes identification of resources for local fertilizer production, harvesting, storage, planning of reclamation activities, determining the need for industrial mineral fertilizers, organization of their acquisition, storage and application to the soil. It should be provided the possibility of fertilizer mixing and application of fertilizers in a given ratio of nutrients, taking into account soil fertility, requirements of crops and adopted agrotechnics.
In the planning of these works takes into account integrated mechanization of technological processes for the application of fertilizers. An important step in developing a system of fertilizers in the farm is to discover the local fertilizer resources, chemical meliorants, the development of technologies for their rational use, the provision of material and technical base. The system should be based on scientifically based specialized crop rotations and strive to provide a positive or deficit-free balance of nutrients and organic matter in the soil-plant system.
Fertilizer system in crop rotation
Fertilizer system in crop rotation – the distribution of fertilizers in crop rotations, taking into account their specialization, local soil and climatic conditions, economic and fertilizer resources of the enterprise.
The system of fertilizers in the crop rotation means the distribution of organic and mineral fertilizers, ameliorants on the fields of the crop rotation taking into account the provision of maximum agronomic and economic effect under the condition of reproduction of soil fertility, improving their agrochemical, agrophysical and biological properties.
The system of fertilizers in crop rotation is based on scientifically grounded system of crop rotations in the farm, first of all, specialization of crop rotations. The effectiveness of fertilizers in the rotation with proper alternation of crops is higher than in monoculture or violation of alternation.
When developing the fertilization system in the rotation the system of soil-protecting tillage, forecrop, the nature of the crop residues, their impact on the agrochemical, agrophysical properties, microbiological activity, responsiveness of certain crops on some soils on calcium, magnesium, sulfur, trace elements are taken into account. Thus, on sandy soils shows the need for potassium and magnesium fertilizers, in neutral and carbonate soils – in manganese, peat-bog – in copper, on sod-podzolic, especially calcareous soils – nitrogen fertilizers.
The main indicator of fertilizer use in crop rotation is the amount of each type of fertilizer per 1 ha of crop rotation area.
Fertilization system of individual crops
Fertilization system of individual crops is a plan of application of organic and mineral fertilizers, which provides doses, forms, timing and methods of application, taking into account the planned yield, the biological needs of culture in nutrients, crop rotation, rotation features, agricultural practices, soil and climatic conditions, agrochemical properties of soils, natural fertility, fertilizer properties, the combination of organic and mineral fertilizers, economic conditions.
The amount of fertilizers for each crop is calculated taking into account the economic removal of nutrients by the planned harvest.
Table. Removal of main nutrients from the harvest, kg per 100 kg of main products (by V.A. Demin)
|Corn (green mass)|
*Nitrogen used from soil and fertilizer without nitrogen fixation
According to the reference data, determine the amount of NPK to obtain the planned yield. On the basis of agrochemical soil survey cartograms the amount of nutrients contained in each field of the crop rotation is established. Since plants can only use a certain portion of these substances, set the amount of nutrients available to plants, taking into account the coefficients of their use from the soil and therefore reduce the calculated dose of NPK.
Fertilizers cannot be fully used by plants because some of them are assimilated by microorganisms, leached or transferred to an inaccessible form for plants. In addition, crops may absorb the same fertilizer differently.
Table. Plant use of NPK from manure and mineral fertilizers, %Basics of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. - Moscow: "Bylina", 2000. - 555 p.
|Used in the first year|
|Used in the second year|
|Used in the first year|
|Used in the second year|
Considering all of the above factors, an adjustment is made to the calculated rate, obtaining the final amount of nutrients for each crop needed to obtain the planned yield.
After determining the rates of nitrogen, phosphorus and potassium for the crops, the data is summarized in a table for the crop rotation, which specifies the methods and timing of fertilizer application in kilograms of active substance or in terms of specific fertilizers.
Fertilization systems in the rotation and individual crops are interrelated. If an effective fertilizer system is developed based on optimizing plant nutrition with macro- and microelements, which allows to realize the potential productivity of the crop in the rotation, then the rotation as a whole will give the maximum productivity.
Fertilization system provisions
The system of fertilization in the crop rotation is not a simple summation of fertilizers of individual crops, but a complex combination of the action of biological, physiological and biochemical factors of plants with physical, physical and chemical and biological factors of the soil and human influences on the conditions of growth and development of plants.
The general basic provisions of the scientific system of fertilization:
1. The greatest efficiency of fertilizers is manifested in the high culture of farming with the use of a set of agrotechnical measures and the constant reproduction of soil fertility. The importance of agrotechnics increases with the use of high doses of fertilizers. High doses of fertilizers cannot compensate for violations of other components of scientific farming.
2. All cultivated plants during vegetation should be provided with the optimal amount and ratio of nutrients, which is achieved by applying fertilizers and mobilization of soil nutrients. For example, young plants have an underdeveloped root system, so they are sensitive to the lack of nutrients, especially phosphorus, which subsequently has a negative impact on plant growth and yield formation.
At a young age, plants are also sensitive to an increased concentration of salts. In the second half of the growing season with the development of root system and vegetative mass the increased need of plants in nutrients is satisfied by mineral fertilizers and mobilization of fertility.
3. Proper use of fertilizers also implies their layer-by-layer placement in the soil in the zone of root system development. In different periods of life plants consume different amounts of nutrients and need different concentrations of soil solution. For example, the phosphorus of superphosphate, usually moves along the soil profile and is fixed in the places of its application. There is a need to apply fertilizers at different times and soil layers: under plowing (main application), at sowing (pre-sowing) and during the growing season (top dressing). All of these techniques are important when developing a system of fertilizing crops. The combination of these techniques allows you to create optimal nutritional conditions for crops according to their needs.
4. If a farm has several crop rotations, it is important to properly distribute fertilizers, taking into account their specialization. First of all fertilizers are provided for vegetable rotations, which are the most demanding to the provision of nutrients. In addition, these crops are a good payback for the fertilizer applied. Field crop rotations with a saturation of row crops, especially technical crops, are also demanding to nutritional conditions. High doses of fertilizers are used in forage crop rotations saturated with corn and forage root crops. In general the general principle of fertilizer distribution in crop rotations is the specific weight of economically profitable crop, which by increase in yields most fully pays for the unit of fertilizer made.
5. Organic and mineral fertilizers when applied systematically are approximately equally effective, except for certain conditions.
Organic fertilizers are mainly applied in crop rotations, saturated with highly productive fodder crops, mineral fertilizers – in field crop rotations, saturated primarily with grain crops and placed on the massifs away from livestock farms. Consideration is also given to the fertilization of fields in previous years, primarily with organic fertilizers.
Alternation of crops in the rotation allows for more effective use of the effects of organic and mineral fertilizers. For example, manure in the first year after application is used by about half, the rest is used by the second and third crops. Effects of some phosphorus fertilizers lasts 3-4 years, potassium – 2-3 years, nitrogen because of the mobility and poor fixation in the soil almost do not manifest themselves after action. The introduction of lime or gypsum affects the yield even after 10-15 years.
In the rotation of manure and mineral fertilizers tend to use under fallow-occupied crops and row crops, as the most demanding, then under the winter and spring cereals. The joint use of organic and mineral fertilizers in the rotation increases their effectiveness.
6. Systematic application of phosphate fertilizers leads to the accumulation of mobile phosphate in the soil and increases the effectiveness of nitrogen fertilizers. In nitrogen deficiency, the effect of phosphorus fertilizers is reduced.
7. Scientific system of fertilizers in crop rotation provides constant control over the reproduction of soil fertility, balance of nutrients and humus.
8. When developing a system of fertilizers the temperature conditions and amount of precipitation falling out during the vegetation period should be taken into account. With excessive moisture some of the nutrients are washed away, and increased temperature leads to increased microbiological processes of decomposition of soil organic matter.
Zonal and organizational-economic peculiarities of fertilization systems
When developing a fertilization system, natural, agrotechnical and organizational and economic conditions that determine the effectiveness of fertilizers in a particular zone are taken into account.
Many nutrient-demanding crops (sugar beet, corn, potato, sunflower) are grown in the forest-steppe and steppe part of the Central Black Earth zone of Russia, but in this zone the limiting factor for yield is moisture, so the use of agronomic techniques aimed at accumulation and preservation of moisture will increase the efficiency of fertilizers. According to the Research Institute of Agriculture of South-East (Saratov), the efficiency of manure in wet years is 1.5 times higher than in dry years due to better water regime and slow decomposition of manure. In this zone, the depth of fertilizer embedding is also important: the top soil quickly dries out, so the applied nutrients become unavailable for plants.
Table. Fertilizer system in cereal-beet crop rotation (manure in tons, NPK in kg per 1 ha)Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. - Moscow: "Bylina", 2000. - 555 p.
|Spring cereals + clover|
|Clover 1st year of use|
|Corn on grain|
In the Central Black Earth zone of Russia, phosphorus fertilizers are effective, potash fertilizers give a small increase in yield, and on saline soils and solonetz are ineffective at all.
Irrigated farming is widespread in the steppe areas, the fertilizer system of which is characterized by higher doses of mineral fertilizers than in rainfed areas. According to experiments carried out in Samara region, under irrigation and the effect of fertilizers, the protein content in the grain of winter wheat increases by 2.8%, spring wheat – by 1.8%.
High doses of fertilizers are applied to cotton, as the most valuable technical crop of irrigated agriculture. More than 0.8-1 tons of mineral fertilizers per 1 hectare are applied to it. During the growing season, cotton is fertilized several times, using 25-30% of the total amount of fertilizers. High doses of fertilizers are also used for vegetable crops.
When developing a fertilizer system, the acidity of the soil is taken into account, and lime is used if necessary. As a rule, lime is applied in the fallow field and under row crops.
Fertilizer application methods
Several methods of fertilizer application are used in production:
- main (basic);
- before sowing (pre-sowing);
- post-sowing, or top dressing (feeding).
Main (basic) fertilization provides plants with nutrients throughout the growing season. This fertilizer is used by the plants when their root system is well developed. Main fertilizer is applied to a sufficient depth in a moist layer of soil, most often under plowing and in large quantities.
In different zones of Russia, the basic fertilizer is applied at the time optimum for the region. If deep plowing is done in the fall and surface tillage is done in the spring, the basic fertilizer is incorporated in the fall. Where, in addition to autumn tillage, spring plowing is used, it is advisable to apply mineral fertilizers, except phosphorus fertilizers, in the spring.
Before sowing (pre-sowing) and with-sowing fertilization is carried out before or at the same time as sowing. These fertilizers provide young, developing plants with nutrients during the first phases of growth. Doses of such fertilizers are small. They are put into the soil during pre-sowing cultivation or a little deeper into the rows or wells when planting. These methods of application are the most effective, but if the top layer of soil dries out in areas with insufficient moisture, the effect of such fertilizer decreases.
Post-sowing fertilization, or top dressing, (feeding), provides plants with nutrients during certain phases of growth and development, when there is the greatest need for certain nutrients. In the spring, after snowmelt, winter crops need feeding primarily with nitrogen fertilizers, and to a lesser extent with phosphorus and potassium fertilizers. For solid crops, fertilizers are distributed evenly over the field. Fertilization of row crops is carried out during the inter-row cultivation by cultivator-plant feeders.
Different methods of application complement each other, so the right combination of them increases the effectiveness of fertilizers.
Fertilizer application rates (doses)
Determination of scientifically justified optimal doses and ratios of fertilizers under crops, taking into account biological characteristics and crop rotation, soil-climatic and organizational and economic conditions, is an important part of agrochemical research systems and practice of fertilizers, meliorants, plant protection agents and growth regulators.
In practice, the fertilization system in the agrocenosis consists of stages:
- long-term (at least for a rotation of crop rotation) general scheme of optimal doses and ratios of fertilizers, developed taking into account the fertility of soils of the agrocenosis;
- annual plan of fertilizers use – correction of doses of the general scheme, taking into account actual placement of crops on the fields, differences in the fertility of fields, weather conditions and organizational and economic factors of a particular year and distribution of adjusted doses by methods and timing of application, indicating specific optimal forms of fertilizers;
- calendar plan for purchase and application of fertilizers, made with indication of specific fertilizer volumes for the whole fertilized area;
- correction of annual plan doses during implementation according to results of soil and plant diagnostics of plant nutrition.
All listed stages of fertilizer system are interconnected, and each subsequent stage is a logical continuation of the previous one.
Agrochemistry. Textbook / V.G. Mineev, V.G. Sychev, G.P. Gamzikov et al. – M.: Publishing house of the All-Russian Scientific Research Institute named after D.N. Pryanishnikov, 2017. – 854 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Evtefeev Y.V., Kazantsev G.M., Bases of agronomy: textbook. – M.: FORUM, 2013. – 368 p.: ill.
Plant growth regulators, or plant hormones, phytohormones (Greek: hormon – inducing, causing), are low-molecular-weight organic compounds that participate in the interaction of cells, tissues and organs. They are needed in small amounts to initiate and regulate physiological and morphological processes of plant ontogenesis.
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
Hormones mediate physiological processes, converting specific environmental signals into biochemical information. Hormones formed in plants are called endogenous, those used by humans to treat plants are exogenous.
The plant’s need for hormones is 10-13⋅10-5 mol/L, in most cases synthesized in sufficient amounts by the plant itself. They are synthesized in individual parts of the plant, but spread throughout the body. Under their action, metabolism is regulated. Hormones exhibit physiological effects on:
- enzymes and enzyme systems;
- metabolism of proteins, lipids, nucleic acids;
- informational and transport ribonucleic acids;
- deoxyribonucleic acid.
The effect of the action of hormones in some cases is reduced to a temporary change in the intensity of biochemical reactions, in others – manifested in a steady deviation of processes, in the third – in morphological changes affecting the somatic sphere of the body, in the fourth – in hereditary morphological changes.
Among the most active and studied compounds of hormonal action of plant origin are auxins, gibberellins, cytokinins, abscisic acid and ethylene.
Unlike animals, plants do not have glands that secrete hormones.
The action of hormones on plant metabolism is specific: gibberellins are involved in transcription, that is, the transfer of information about the nucleotide sequence of DNA to informational RNA during protein synthesis, cytokinins – in translation, that is, the process of translation of the nucleotide sequence of informational RNA into the sequence of amino acids of the synthesized polypeptide, auxins – in changes in membrane permeability, abscisins inhibit ion transport and related cell growth processes, ethylene acts as a “permissive” growth factor, controlling the balance in the stimulant-inhibitor system.
Auxins, or indolylacetic acid (IAA) compounds, are formed in areas with high meristematic activity: in the apexes of stems, in forming seeds, from where they move in the basipetal direction, reaching lateral shoots and leaves.
Auxins initiate cell division and influence the rate of cell stretching, regulate the formation of conductive bundles, and determine the phenomena of plant photo- and geotropism related to the asymmetry of their distribution. Activation of cell stretching occurs when auxin stimulates proton secretion into the cell wall. The resulting increased concentration of hydrogen ions leads to a more active enzymatic cleavage of transverse bonds connecting cellulose microfibrils.
Other properties of auxins are the ability to induce parthenocarpy, delay leaf and ovary fall, and activate root formation in cuttings. Tissues enriched with auxin have an attraction effect, i.e., they can attract nutrients. Auxin provides correlation between the organs of the growing plant.
Gibberellic acids (GAs) are a class of plant hormones and tetracyclic diterpenoids involved in plant growth and development, including seed germination, root growth, stem elongation, leaf outgrowth and floral induction, anther development, seed and pericarp growth (Weiss et al., 2007).
Gibberellins are phytohormones derived from the fluorene series. They stimulate cell division and stretching of apical and intercalary meristem cells. Under the influence of gibberellins, leaves, flowers and inflorescences elongate. Gibberellins enhance stem growth more strongly than auxins. At the same time, gibberellins have almost no effect on root growth. They participate in the processes of seed germination and transition of long-day plants to flowering. They promote the formation of parthenocarpic fruits.
Gibberellins can shift the sex of plants to the male side. Their influence on plant metabolism is associated with their participation in nucleic metabolism: their action induces synthesis of matrix RNA, which encodes the formation of hydrolytic enzymes, primarily amylases.
Gibberellins are synthesized mainly in the leaves and from there move up and down the stem.
Cytokinins are phytohormones, derivatives of purines, stimulate cytogenesis, seed germination, promote bud differentiation. They have the ability to inhibit the aging process of plant organisms and maintain normal metabolism of yellowed leaves, causing their secondary greening.
Cytokinins are involved in mobilization-attraction of nutrients to localized sites: fruits, seeds, tubers. They release lateral buds from apical dominance caused by auxin, stimulate their growth. At the molecular level, cytokinins in complex with a specific protein receptor increase RNA polymerase activity and chromatin matrix activity, with an increase in polyribosomes and protein synthesis. Cytokinins are involved in the synthesis of the enzyme nitrate reductase and the transport of H+, K+, Ca2+ ions.
They are formed in roots, from where they move up the stem in acropetal direction.
Abscisins are natural inhibitors of terpenoid nature. They inhibit growth in the phase of cell division and stretching, do not exhibit toxic effect even in high concentrations. They induce plant dormancy, accelerate leaf and fruit drop (abscission), inhibit coleoptile growth, inhibit seed germination.
By inhibiting the excessive growth of the stem, abscisins direct the metabolites to form the photosynthetic apparatus, i.e. coordinate the growth process. They participate in stress mechanisms by regulating stomatal movements.
Abscisic acid accumulates rapidly in tissues when plants are exposed to unfavorable environmental factors, first of all water deficiency, causing closure of stomata, reducing transpiration and reducing energy consumption. At molecular level abscisins inhibit DNA, RNA and protein synthesis. They can decrease the functional activity of the H+-pump.
Abscisic acid is synthesized in the leaves, transported up and down the stem. It is also formed in the root sheath.
Ethylene is a specific hormone synthesized in all plant organs from methionine. It contributes to the regulation of plant growth and development. It participates in maintenance of apical curvature in seedlings grown in darkness, causes epinasty, i.e. rapid growth of the upper side of the organ, resulting in downward curvature of the leaf or petal. For this reason it is used to accelerate flower opening. Leaf lowering under the action of ethylene reduces transpiration.
Ethylene is responsible for auxin-controlled suppression of growth of lateral buds showing apical dominance. It inhibits cell division and seedling elongation, changes the direction of cell growth from longitudinal to transverse, reducing the length and thickening the stem. By promoting tissue aging, ethylene accelerates leaf fall, flower wilting, and accelerates fruit ripening.
In most cases, it increases dormancy period of seeds and tubers, promotes shift of plant sex to female side, plays role of mediator of hormonal complex in processes of correlation interactions in plant. Inhibits polar transport of auxin and promotes formation of its conjugates. Ethylene regulates stress response in plants. On molecular level increases cell membrane permeability and protein synthesis rate.
Brassinosteroids are hormones that support the immune system of the plant, primarily in stressful situations. Steroids, like gibberellins and abscisic acid, belong to the class of terpenoids.
Brassinosteroids are contained in every plant cell, but their natural level in the changed ecological situation is insufficient to maintain immunity and normal development throughout the growing season.
Preparations - plant growth stimulants
Campozan M is used to prevent lodging of fiber flax, winter rye, winter barley.
Rosaline is used on cotton to prevent boll drop and increase raw cotton yields.
Fospinol increases potato yield by 15-20%, reduces the incidence of fungal and viral diseases, improves the potato tubers’ storability.
Tur, or chlormequat chloride, and chlorcholine chloride is used in crops, especially in winter crops. It prevents lodging of high-yielding crops by thickening straw, strengthening mechanical tissues and reducing stem length.
Immunocytophyte is a mixture of polyunsaturated fatty acids with high content of archidonic acid. It is used on cereals, legumes, root and tuber crops, vegetables, technical and fruit crops as a multipurpose stimulator of protective responses, growth and development of plants.
Stimulates natural immunity to diseases such as phytophthora, various types of scabs, blackleg, powdery mildew, rot, bacterioses. It accelerates seed germination, fruit ripening, cork layer formation on tubers and root crops; increases flower size, green mass and bushiness; provides yield increase by 20-30%, reduces yield losses during storage.
Application of plant growth regulators
For effective application of plant growth regulators, the conditions must be met:
- positive effects can be achieved only if endogenous phytohormones are lacking in the plant or in individual organs;
- cells, tissues and organs must be susceptible to phytohormones;
- the effect of all growth regulators depends on the concentration, overdose leads to an inhibitory effect;
- optimal supply of water and nutrients to plants.
Growth regulators do not replace plant nutrition. According to M.H. Chailahan (1976), they increase “appetite” and therefore stimulate growth processes.
Plant growth regulators are used to:
- stimulating rooting of cuttings;
- obtaining parthenocarpic (seedless) fruits;
- increased production of seedless grape varieties;
- thinning of flowers and ovaries of fruit crops;
- weed control;
- inhibition of stem elongation;
- regulation of dormancy;
- acceleration of fruit ripening.
Among the growth regulators of auxin nature, 1-naphthylacetic acid (1-NAA), indomethyl-3-oilic acid (IMA), 2,4-dichlorophenoxyacetic acid (2,4-D), 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), 2-naphthoxyacetic acid (2-NAUC), 4-chlorophenoxyacetic acid (4X), maleic acid hydrazide (MAH), 2-methyl-4-chlorophenoacetic acid (2M 4X) and 2,4-dichlorophenoxyoilic acid (2,4-DO). 1-NAA and IMA are successfully used in horticulture for rooting cuttings, improvement of seedlings survival and restoration of the root system of transplanted shrubs and trees.
Gibberellins have practical application. Spraying of vine plants during flowering with the aqueous solution containing 30-35 g/ha of gibberellic acid increases the yield of seedless (sultanas) varieties by 10-15%. It is also used in the cultivation of citrus.
Cytokinins have found application in tissue culture. They are a factor necessary for obtaining a culture of dedifferentiated callus tissue as well as for the induction of then organogenesis and somatic embryogenesis. Cytokinin is also necessary for maintaining the functional activity of isolated tissues and organs.
Ethylene is used as a stimulant of fruit and vegetable ripening.
Retardants are synthetic substances that inhibit the synthesis of gibberellins, inhibit the growth of stem and vegetative shoots, giving the plant resistance to lodging.
Retardants selectively inhibit stem growth without having a negative effect on physiological and biochemical processes. The action is based on the inhibition of cell division in the medial and subaerial zones of the meristem of the growing cone, which forms the stem. Retardants have no effect on the apical meristem zone, from which leaves and generative organs develop. These regulators inhibit the stem cells growth in length and enhance their division in transverse direction, due to which the stem becomes shorter and thicker. At the same time, the development of mechanical tissues increases: cell walls thicken, the number of vascular-fiber bundles increases. At the same time, retardants promote root growth, increase the assimilative surface area of leaves and plastid pigment content, and increase plant resistance to adverse environmental factors.
More than a thousand chemical compounds with retardant properties have been studied. Most belong to four groups of substances:
- quaternary onium compounds;
- hydrazine derivatives;
- triazole derivatives;
Among the retardants on the basis of quaternary onium salts, chlorcholine chloride (CCC), morphol, and pike are common. The characteristic retardant effect of these drugs is due to their ability to interrupt gibberellin biosynthesis. Their administration blocks the formation of geranylgeranyl pyrophosphate and its subsequent cyclization into entkauren, which is an intermediate in the synthesis of gibberellins.
Triazole derivatives block gibberellin biosynthesis by preventing the oxidation of entkauren into caurenic acid.
Ethylene-producing drugs do not interrupt gibberellin biosynthesis, their action is associated with an antigibberellin effect that occurs during the formation of the hormone-receptor complex or in the subsequent stages of realization of the hormonal activity of gibberellins.
The mechanism of action of hydrazine derivatives is also not associated with the inhibition of gibberellin synthesis, but is due to the suppression of their hormonal activity.
Of all known retardants, chlorocholine chloride (CCC), better known as Tur, has the greatest practical value. This retardant gives good results in cereal crops. In order to increase resistance to lodging chloroquine chloride is applied in the period of tillering – the beginning of piping at the rate of 3-12 kg/ha. It does not reduce the quality of grain, increases the yield, and reduces the economic costs of harvesting.
Retardants show high efficiency also on rice crops.
Table. Rice yield of Krasnodar 86 variety when using retardants (Sheudzhen A.Kh., 2005)
|CCC, 10 g/ha|
|Oriz, 30 kg/ha|
|Sumadik, 30 kg/ha|
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Microbiological and bacterial fertilizers are preparations containing highly active microorganisms that improve the nutritional conditions of crops.
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
The level of potential and effective soil fertility is determined by the intensity and direction of microbiological processes, which are regulated by the number of microorganisms.
Microbiological and bacterial preparations contain specific strains of microorganisms, under the action of which the processes of transformation of compounds containing nutrients are activated in the soil.
Preparations containing strains of nitrogen-fixing bacteria are widely used. The interest in the microbiological fixation of atmospheric nitrogen is due to the role of this process in the nitrogen balance and its prospects as a source of nitrogen for the growing needs of agriculture. At the same time, the arguments are its harmlessness for humans and the environment at relatively low energy consumption for activation of nitrogen-fixing microorganisms.
According to field studies of Russian and foreign scientists, if agricultural crops cover 10-20% of their nitrogen demand by nitrogen fixation, application of inoculation will make a significant contribution into nitrogen balance.
Preparative forms of microbial fertilizers are: liquid, granular, gelatinous, and bulk.
Countries producing bacterial fertilizers and production volumes:
- U.S. – 20 million ha/portion annually;
- Canada – 2.5 million hectares/portion annually;
- Austria – 6-9 million hectares/portion annually;
- Brazil – 4-6 million hectares/portion annually;
- India – 2-4 million hectares/portion annually;
- Argentina – 2-3 million hectares/portion annually;
- Uruguay – 1-2 million hectares/portion annually;
- Russia – 0.3 mln ha/portion annually.
Seed pre-treatment with bacterial fertilizers can be carried out with or without adhesive. A 2.0% aqueous solution of sodium carboxymethylcellulose is used as an adhesive agent.
Bacterial fertilizers stored in dry rooms, protected from precipitation and direct sunlight, storage temperature from 0 to + 4 °C. Shelf life depends on the type and form of bacterial fertilizers.
In world practice, attention is paid to the role of soil biota in improving phosphorus nutrition of plants.
Nitragin is a bacterial preparation containing active races of nodule bacteria, Bacterium radicicola, which live on the roots of legume crops and assimilate atmospheric nitrogen using the carbohydrates coming to the roots. Each legume crop corresponds to its specific nodule bacteria. Therefore, depending on the crop, the nitragin must contain specific, highly active and virulent strains of nodule bacteria
According to specificity, the following groups of bacteria are distinguished:
- 1st for clover;
- 2nd for pea, vetch, lentil, faba bean;
- 3rd for alfalfa, melilot and fenugreek;
- 4th for lupine, seradella;
- 5th for soybeans;
- 6th for beans;
- 7th for mung bean;
- 8th for peanuts and cowpea;
- 9th for chickpea;
- 10th for sainfoin.
Inoculation is inoculation of nodule bacteria to legume crops. It is carried out by treating seeds of leguminous plants with the preparation. During germination, nodule bacteria enter plant roots.
Rhizobacterin and its advanced form Rhizobacterin-C is a preparation developed on the basis of associative diazotroph. The titer is 2-2.5 billion viable cells/ml. Promotes atmospheric nitrogen fixation, peroxyacetic acid biosynthesis, suppression of root pathogens. The form is liquid. Designed for pre-sowing treatment of grain crops (200 ml/ha) to increase yield, product quality and intensify the biological nitrogen fixation.
The preparation is based on nitrogen-fixing microorganisms (Klebsiella planticola 5) characterized by high colonizing ability, growth stimulation, antimicrobial action.
Atmospheric nitrogen assimilation allows reducing the recommended doses of nitrogen fertilizers for grain crops by 15-30 kg/ha. Yield increase averages 0.5-0.6 t/ha for barley, 0.6 t/ha for winter rye, 0.35-0.45 t/ha for spring and winter wheat.
Replacement of mineral nitrogen fertilizer with biological does not mean its productive use, because plant metabolism also depends on other nutrients, particularly phosphorus. With its lack of nitrogen is not included in the composition of proteins and nucleic acids, accumulates in the form of nitrites and nitrates, worsening the quality of production.
Rhizotorfin contains nodule bacteria of the genus Rhizobium, which live on the roots of legume plants and provide symbiotic fixation of air nitrogen. It is used only under legume crops. Of the accumulated by these crops 100-300 kg of nitrogen per hectare per year, 1/3 is consumed by plants from soil, 2/3 is assimilated by nodule bacteria from the air.
There are 11 species of Rhizobium bacteria (according to L.M. Dorosinsky). Each species infects one or more species of legumes, so rhizotorfin is prepared for a particular legume.
It is produced in polyethylene bags; the weight of bacteria is calculated for one, two or five hectare portions.
Seeds are treated (inoculated) with the drug before sowing. Risotorfin increases the legume yield by 10-15%; in farms growing them for the first time it increases it by 50-100%.
Rhizotorfin is produced on the basis of sterilized peat. It is produced in a polyethylene packets packaged in the calculation of 1, 2 or 5 hectare portions with the indication under what culture this preparation is designed and what strain of bacteria. Shelf life – 6 months. Stored in a dark, dry room separately from pesticides at 3-15 °C. At subzero temperatures, as well as above 15°C, some of the nodule bacteria die, and overheating is more dangerous. If rhizotorfin has been subjected to freezing during transportation or storage, it should be kept at 13-15°C for 7-10 days.
Azotobacterin is a bacterial preparation containing a culture of Azotobacter chroococcum, a microorganism free-living in the soil with the ability to assimilate atmospheric nitrogen.
Azotobacter releases vitamins and growth substances, has fungistatic action, i.e. prevents the development of fungi, protecting plants from infection.
Azotobacterin is used in the cultivation of any crops. Two types of Azotobacterin are produced as fertilizers: humus-soil, or peat, and agar.
Phosphobacterin is a preparation containing spore-bearing bacterium Bacillus megaterium var. phospaticum capable of mineralizing phosphorus of organic compounds.
It is available in dry and liquid form. Dry phosphobacterin contains bacterial spores mixed with kaolin. 250 g of powdered phosphobacterin is consumed per 1 ha.
Phytostimophos – phosphate-mobilizing microorganisms, live culture and growth-stimulating metabolites of Agrobacterium-radiobacter microorganisms. The drug titer is 6-10 billion viable cells per 1 ml. Growth-stimulating biopreparation performs microbial transformation of insoluble phosphates of soil and fertilizers into a plant-accessible form.
The product bacteria are able to colonize the roots of legume and nonlegume crops, forming associations. Phytostimophos is designed for microbiological phosphate-mobilization and yield increase of winter and spring cereals, corn, legumes and vegetable crops. The drug form is liquid. Consumption rate is 200 ml/ha.
The preparation increases mobility of hardly soluble phosphates of soil and fertilizers by 10-20%, decreases recommended doses of phosphate fertilizers by 15-30%, increases crop yield by 20% on average: increase of yield of fodder root crops – 10-25 t/ha, sugar beet – 9.0-9.5 t/ha, vegetable crops – 6-7 t/ha, legume crops – 0.25-0.35 t/ha.
Complex application of bacterial fertilizers
In a number of countries, joint inoculation of crop seeds with preparations of nitrogen-fixing and phosphate-mobilizing bacteria is successfully used. This allows to simultaneously improve nitrogen and phosphorus nutrition of plants and reduce the doses of mineral fertilizers.
Rizobacterin + Phytostimophos – synergistic binary preparations on the basis of diazotrophic and phosphate-mobilizing microbes. The form of the drug is liquid.
"Silicate" bacteria preparations
“Silicate” bacteria preparations are bacterial preparations based on the spore-forming culture, Bacillus mucilaginosus siliceus. Silicate bacteria can break down aluminosilicates, making soil potassium available to plants. The breakdown of aluminosilicates is caused by acids produced by the microorganisms. “Silicate” bacteria multiply well under conditions of adequate moisture, aeration, and a near-neutral environment. Acidic soils are not favorable for their life activity.
The preparation is used by treating the seeds. Dry spore and agar preparations are prepared as bacterial fertilizer.
Vesicular-arbuscular mycorrhiza (VAM), ectomycorrhiza and endomycorrhiza are soil microflora that form symbiotic associations with higher plants. It improves plant growth in the absence of available phosphorus by improving phosphorus nutrition of plants. In symbiosis between the higher plant and fungi, the fungal mycorrhiza provides the plant with water and dissolved mineral salts, and the fungi use carbohydrates and organic compounds synthesized by the higher plant. The biological importance of mycorrhiza also lies in increasing the absorbing surface of the plant roots due to the mycelium of the fungus.
Endomycorrhizal fungi cultures have been isolated from natural and recultivated soils.
Vesicular-arbuscular mycorrhiza is an association in which Zygomycete fungi form arbuscules, hyphae, and vesicles in the root cells of higher plants.
Their positive effect on the yield of oats, barley, soybeans, and vetch and on the phosphorus supply to plants when grown on soil with a low content of mobile phosphorus has been proved. Mycorrhization of white clover seeds sown in grasses increases hay yield by 17% (control – 1.8 t/ha) and is equivalent to superphosphate effect at the rate of 90 kg/ha. At the same time, the proportion of clover in the composition of the herbage increased. Onion inoculation was noticeably evident on irrigated lands: the yield increased by 97%.
Joint inoculation of clover and other legumes with mycorrhiza and nodule bacteria is effective: the former contributes to phosphorus nutrition of plants, the latter to nitrogen nutrition. For example, in Wales, clover inoculated with mycorrhiza and nodule bacteria gave a yield with dry matter content 3 times higher, shoot formation increased 2-fold, and rhizobium nodule formation increased 5-fold.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Plant growing/P.P. Vavilov, V.V. V., Gritsenko, V.S. Kuznetsov, et al; Edited by P.P. Vavilov. – M.: Agropromizdat, 1986. – 512 p.: ill. – (Textbook and textbooks for higher education institutions).
Humates, or humic acid-based fertilizers, are a group of natural, high-molecular-weight plant growth regulators and are compounds based on humic acids. They are non-toxic, non-carcinogenic, do not cause mutations and have no embryological activity. Residual amounts of humates are not detected in plants because they are easily and quickly incorporated into plant metabolism.
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
- Mineral fertilizers
- Complex fertilizers
- Organic fertilizers
When humic acids are used as plant growth regulators, it is not the humic acids themselves that have physiological activity, but their salts of the univalent alkaline metals (sodium and potassium) and ammonium. This is due to the fact that humic acids are insoluble in water, so they are not absorbed by plants, while salts of the monovalent alkaline metals and ammonium are well soluble in water and accessible to plants.
Humic acids have a versatile effect: they activate bioenergetic processes, stimulate metabolism and synthetic processes, improve penetration of nutrients through the plasmalemma, enhance enzyme systems, increase adaptive properties of the plant organism. Depending on environmental conditions, they may differ in persistence and activity, so they can be used as fertilizers and plant growth stimulators.
The reason of physiological activity of humic acids is their action on the bioenergetic system of plant organism (Khristeva L.A., 1973). Increase in energy reserves of the organism promotes protein synthesis, due to which plant resistance under extreme conditions and photosynthetic capacity increase.
The ability of humic acids to complexation and their sorption activity make it possible to use them for binding heavy metals to insoluble compounds on polluted soils.
Humic acids interact with metal cations in different ways: calcium ions form calcium salt-like humates, in which an ionic form of carboxyl groups is observed. Zinc ions replace hydrogen of carboxyl groups. Copper replaces the hydrogen of both carboxyl and phenolic groups. In all cases, the redeposition of humic acids in the form of insoluble or slightly soluble metal salts or complexes occurs.
Humates are involved in soil structure formation: on light soils aggregation takes place, on heavy soils they prevent formation of crusts and cracks, improve aeration, water-holding and water-transmitting capabilities.
The use of humates in agriculture contributes to:
- increase the yield of cereal, vegetable and forage crops;
- Increasing the germination and germination energy of seeds;
- strengthening of root formation and metabolism of plants, absorption of
- elements of mineral nutrition, increasing the resistance of plants to diseases, frost and drought.
Sodium, potassium and ammonium humates are used. Sodium and potassium humates are obtained by saturation with potassium or sodium hydroxides. Ammonium humate is obtained by treating raw material with ammonia solution.
For irrigation, a 5% solution of humate diluted at a ratio of 1:1000 is used, for seed treatment – 1:500, for treatment of tubers and seeds of cereal crops – 1:250. Spraying of plants during vegetation period is carried out 2-4 times.
Microelements, organic acids, biologically active substances, amino acids, vitamins can be added to solutions of humic acid salts which are used by germinating seeds, plants and microorganisms living in the soil. More than 60 preparations, grouped into a group of “Humic Acid Fertilizers” are produced.
The different chemical composition of the preparations expands the range of their application. They can be used for seedbed preparation and spraying of vegetative plants. Production tests of these preparations in various soil and climatic conditions have shown their positive impact on the yield of all crops. Vegetable, fruit and forage crops were the most responsive. It is reasonable to combine application of humic acid-based fertilizers with the pre-sowing preparation of seeds and spraying of crops with plant protection agents. Combined application with pesticides also has the advantage that they remove the stress effects of toxic chemicals on cultivated plants.