Fertilizer system

Concept of the fertilizer system

Fertilizers, depending on their types, doses, times and methods of application, their ratios and soil-climatic conditions, have unequal effect and aftereffect. They are most fully used by crops in crop rotations under a certain alternation and structure of sown areas. This determines the need to move from the fertilization of individual crops to comprehensively substantiated fertilizer systems for the crop rotation.

The scheme of the fertilizer system of a crop rotation or agrocoenosis is developed and used for the full rotation of the crop rotation on the basis of the average over 5–10 years of the enterprise’s provision with fertilizers and the state of soil fertility of the fields of the crop rotation, determining the types, doses, ratios and total requirement in kg/ha of active substances, as well as the balance of nutrients. Doses and ratios of fertilizers and ameliorants in the fertilizer system scheme are annually adjusted in fertilizer application plans taking into account the placement of crops and soil fertility of these fields, weather conditions and the availability of fertilizers.

On the basis of the annual plan, a calendar plan is drawn up for the purchase, accumulation and application of fertilizers, indicating amounts and types for the entire fertilized area of the crop rotation or the entire farm. This allows determining the areas of warehouses and storage facilities for agrochemical agents, the sequence of purchasing quantities and types and, accordingly, more effectively managing material and technical resources.

When implementing annual fertilizer application plans, before applying fertilizers, pre-sowing doses are again adjusted based on soil diagnostics results, and when fertilizing crops, based on plant diagnostics results.

The development of a fertilizer system meeting natural and organizational-economic conditions requires qualified knowledge and practical skills. To compile a fertilizer application plan, the following documents are needed:

• organizational-economic plan reflecting crop rotations;
• soil maps and agrochemical cartograms;
• data on actual yields over the last 5 years;
• norms for the application of organic and mineral fertilizers;
• field history book.

For the development of a fertilizer system, information is also needed on the type of soil water regime, relief, susceptibility of soils to water and wind erosion, development of animal husbandry, opportunities for the accumulation and application of all types of local fertilizers, financial resources, technical equipment for fertilizer application, and availability of storage warehouses.

In practice, the fertilizer system in an agrocoenosis consists of the following stages:

• long-term (at least for the crop rotation) general scheme of optimal doses and ratios of fertilizers, developed taking into account the soil fertility of the agrocoenosis;
• annual plan for fertilizer use — correction of the doses of the general scheme taking into account the actual placement of crops by fields, differences in field fertility, meteorological conditions and organizational-economic factors of a specific year, and distribution of the corrected doses by methods and times of application, indicating specific optimal forms of fertilizers;
• calendar plan for the purchase and application of fertilizers, compiled indicating volumes of specific fertilizers for the entire fertilized area;
• correction of the doses of the annual plan during implementation based on the results of soil and plant diagnostics of plant nutrition.

All the listed stages of the fertilizer system are interconnected, with each subsequent stage being a logical continuation of the previous one.

Goals and objectives of the fertilizer system

The goal of the fertilizer system is the annual provision of the maximum possible agronomic and economic efficiency while minimizing negative impact on the environment with the available natural-economic resources of the enterprise.

The objectives of the fertilizer system in an agrocoenosis (farm) are:

• increasing the productivity of cultivated crops and improving product quality with growth of fertilizer application to optimal levels;
• eliminating differences in the fertility of individual fields of each crop rotation at any availability of fertilizers and (or) increasing the soil fertility of fields to the optimal level;
• increasing the return from a unit of applied fertilizers through crop yield increases, that is, increasing the economic efficiency of fertilizers at any availability;
• obtaining certifiable crop products with constant monitoring of changes in agrochemical indicators of fertility of soils;
• increasing labor productivity, organizational-economic and management activity;
• constant compliance with environmental protection requirements and sanitary-hygienic legislation.

The degree of achievement of the goal and objectives varies depending on the biological characteristics of crops, soil-climatic and agrotechnical conditions, and the quantity and quality of applied fertilizers.

Scientific fertilizer system

The scientific fertilizer system can be divided into:

• Scientific-organizational system of fertilizer use on a farm.
• System of fertilizer application in a crop rotation, as a link of the scientific farming system.
• Fertilizer system for individual crops of the crop rotation, based on the application of optimal doses, forms, times and methods of fertilizer application.

All these components are interconnected.

Fertilizer system for individual crops

The fertilizer system for individual crops is a plan for the application of organic and mineral fertilizers, which provides for doses, forms, times and methods of application taking into account the planned yield, the biological needs of the crop for nutrients, the alternation of crops in the crop rotation, the features of agrotechnics, soil-climatic conditions, agrochemical properties of soils, natural fertility, properties of fertilizers, the combination of organic and mineral fertilizers, and economic conditions.

The amount of fertilizers for each crop is calculated taking into account the economic removal of nutrients by the planned yield.

Table. Removal of main nutrients with the harvest, kg per 100 kg of main product (V. A. Dyomin).

Crop	N	P	K
Winter wheat	3.5	1.2	2.6
Spring wheat	3.8	1.2	2.5
Winter rye	3.0	1.2	2.8
Maize (grain)	3.4	1.2	3.7
Maize (green mass)	0.25	0.12	0.5
Oats	3.0	1.3	2.9
Barley	2.7	1.1	2.4
Peas	3.0*	1.6	2.0
Fiber flax	8.0	4.0	7.0
Hemp	20.0	6.0	10.0
Sugar beet	0.6	0.2	0.8
Potato	0.6	0.2	0.9
Clover (hay)	3.1	0.6	0.2
Timothy (hay)	1.6	0.7	2.4

Notes.

^* Nitrogen used from soil and fertilizers without nitrogen fixation.

According to reference data, the amount of NPK for obtaining the planned yield is determined. On the basis of cartograms of agrochemical soil survey, the amount of nutrients contained in each field of the crop rotation is established. Since plants can use only a certain part of these substances, the amount of nutrient elements available to plants is established taking into account the coefficients of their use from the soil, and the calculated NPK dose is correspondingly reduced.

Fertilizers cannot be fully used by plants, since part of them is assimilated by microorganisms, leached, or converted into a form inaccessible to plants. In addition, crops can assimilate the same fertilizer differently.

Table. Use by plants of NPK from manure and mineral fertilizers, %.

Indicators	N	P	K
Manure
- total content	0.5	0.25	0.6
- used in the first year	20-25	25-30	50-60
- used in the second year	15-20	10-15	10-15
Mineral fertilizers
- used in the first year	50-70	15-20	50-60
- used in the second year	0-5	10-15	10-20

Taking into account all the listed factors, a correction is made to the calculated dose, obtaining the final amount of nutrients for each crop necessary for obtaining the planned yield.

After determining the doses of nitrogen, phosphorus and potassium for the crops, the data are summarized in a table by crop rotation, which indicates the methods and times of fertilizer application in kilograms of active substance or in terms of specific fertilizers.

The fertilizer systems in a crop rotation and for individual crops are interconnected. If, on the basis of optimizing plant nutrition with macro- and microelements, an effective fertilizer system has been developed that allows realizing the potential productivity of a crop in the crop rotation, then the crop rotation as a whole will give maximum productivity.

Provisions of the fertilizer system

The fertilizer system in a crop rotation is not a simple summation of fertilizers for individual crops, but a complex combination of the action of biological and physiological-biochemical factors of plants with the physical, physicochemical and biological factors of the soil and human impacts on the conditions of growth and development of plants.

General basic provisions of the scientific fertilizer system:

1. The greatest efficiency of fertilizers is manifested under a high standard of farming with the application of a complex of agrotechnical measures and constant reproduction of soil fertility. The importance of agrotechnics increases with the use of high fertilizer doses. High fertilizer doses cannot compensate for violations of other components of scientific farming.

2. All cultivated plants during vegetation must be provided with an optimal amount and ratio of nutrient elements, which is achieved by applying fertilizers and mobilizing soil nutrients. For example, young plants have a poorly developed root system, therefore they are sensitive to a lack of nutrient elements, primarily phosphorus, which subsequently negatively affects plant growth and yield formation.

At a young age, plants are also sensitive to increased salt concentration. In the second half of vegetation, with the development of the root system and vegetative mass, the increased need of plants for nutrient elements is satisfied through mineral fertilizers and mobilization of fertility.

3. Correct application of fertilizers also implies their layered placement in the soil in the zone of root system development. In different periods of plant life, plants consume different amounts of nutrients and need different concentrations of the soil solution. For example, phosphorus of superphosphate usually moves along the soil profile and is fixed at the places of its application. There is a need to apply fertilizers at different times and to different soil layers: under plowing (main application), at sowing (pre-sowing application), and during vegetation (top dressing). All these techniques are important when developing a fertilizer system for a crop. The combination of these techniques allows creating optimal conditions for crop nutrition in accordance with their needs.

4. If a farm has several crop rotations, the correct distribution of fertilizers taking into account their specialization is important. First of all, vegetable crop rotations, which are most demanding for nutrient supply, are provided with fertilizers. Moreover, these crops repay applied fertilizers well. Field crop rotations saturated with row crops, especially industrial crops, are also demanding regarding nutrition conditions. High doses of fertilizers are used in fodder crop rotations saturated with maize and fodder root crops. In general, the common principle of fertilizer distribution by crop rotations is the share of an economically profitable crop, which, through yield increases, most fully pays for a unit of applied fertilizer.

5. Organic and mineral fertilizers with systematic application are approximately equally effective, except for certain conditions.

Organic fertilizers are mainly applied to crop rotations saturated with highly productive fodder crops, mineral fertilizers — to field crop rotations saturated primarily with grain crops and located on massifs remote from livestock farms. The fertilization of fields in previous years, primarily with organic fertilizers, is also taken into account.

The alternation of crops in a crop rotation allows more efficient use of the aftereffect of organic and mineral fertilizers. For example, manure in the first year after application is used approximately by half, the remaining part by the second and third crops. The aftereffect of some phosphorus fertilizers lasts 3–4 years, potassium fertilizers — 2–3 years, nitrogen fertilizers, due to mobility and poor fixation in the soil, almost do not show aftereffect. The application of lime or gypsum affects yield even after 10–15 years.

In a crop rotation, manure and mineral fertilizers are sought to be used for fallow-occupying crops and row crops, as the most demanding, then for winter and spring grain crops. The joint application of organic and mineral fertilizers in a crop rotation increases their efficiency.

6. Systematic application of phosphorus fertilizers leads to the accumulation of mobile phosphates in the soil and an increase in the efficiency of nitrogen fertilizers. With nitrogen deficiency, the aftereffect of phosphorus fertilizers decreases.

7. The scientific fertilizer system in a crop rotation provides for constant control over the reproduction of soil fertility, the balance of nutrients and humus.

8. When developing a fertilizer system, temperature conditions and the amount of precipitation falling during the vegetation period are taken into account. With excessive moisture, part of the nutrients is leached, and increased temperature leads to intensification of microbiological processes of decomposition of soil organic matter.

The need for liming, the amount of applied mineral and organic fertilizers, and their distribution between crops are decided taking into account the following factors:

• soil conditions — soil type, granulometric composition, acidity, content of mobile nutrients;
• type of crop rotation — field, fodder, specialized, meadow-pasture, vegetable;
• availability of organic fertilizers;
• required assortment of mineral fertilizers;
• availability of lime fertilizers;
• level of agrotechnics;
• availability of highly productive varieties;
• levels of planned yields.

Fertilizer systems must provide for an increase in crop yields and improvement in the quality of plant products from one crop rotation to another.

The fertilizer system is built for each crop rotation on the basis of an agrochemical study of fields (plots), crop requirements, and intensity of technologies, taking into account the soil type and its properties.

List of sources

1. Yagodin B. A., Zhukov Yu. P., Kobzarenko V. I. (2002). Agrochemistry. Ed. B. A. Yagodin. Moscow: Kolos.

2. Evtefeev Yu. V., Kazantsev G. M. (2013). Fundamentals of Agronomy: textbook. Moscow: FORUM.

3. Mineev V. G., Sychev V. G., Gamzikov G. P. et al. (2017). Agrochemistry. Textbook. Ed. V. G. Mineev. Moscow: Publishing House of VNIIA named after D. N. Pryanishnikov.

4. Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Farming and Crop Production. Moscow: “Bylina”.