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Row crops in the crop rotation
Row crops is a group of crops in a crop rotation that combines plants according to their specific influence on the soil, the yield of subsequent crops and the method of cultivation.
The group of row crops includes a large number of crops related to cereals, forage, technical crops and leguminous. They are cultivated in wide rows, which allows to conduct inter-row cultivation and weeding, and to apply mineral fertilizers.
Row crops include root and tuber crops – potatoes, sugar beets, table and forage root crops; leguminous crops – forage and vegetable beans, soybeans, large row sowings of lupine and others.
Features of row crops
Because of their ability to reduce the number of weeds and store available nutrients in the topsoil, row crops are closer to bare fallow in terms of efficiency. Some row crops have a positive effect on water balance.
Most row crops are late spring crops, which allows for several soil treatments before sowing them to kill some of the minor weeds in combination with herbicides and to contain the spread of perennial weeds. Extermination measures are carried out after sowing by means of inter-row cultivation, carried out up to the closing of rows.
The disadvantage of row crops is the high removal of nutrients from the soil. For example, sugar beet at a yield of 30 t/ha removes from the soil 150-180 kg/ha of nitrogen, 45-60 kg/ha of phosphorus, 180-200 kg/ha of potassium. Sunflowers consume up to 60 kg of nitrogen, 20 kg of phosphorus, and 100 kg of potassium to produce one ton of seeds. Potatoes at a yield of 30 t/ha remove up to 300 kg of potassium from the soil. Therefore, row crops are cultivated against large doses of organic and mineral fertilizers, the effect of which may last for several years.
The soil under row crops during the whole season remains in a friable state, contributing to the activation of soil microflora, retention and accumulation of moisture from precipitation. Therefore, for example, after potatoes in a meter layer of soil there remain sufficient reserves of water.
On the other hand, the deep penetrating (up to 4 m) root system of corn and sorghum consumes quite a lot of soil moisture. Sugar beet and sunflower are also characterized by high water consumption.
The negative qualities of row crops include: small amount of plant residues, destructive effect on soil structure and weak soil-protective function. Therefore, when growing them, high doses of organic fertilizers are applied to restore the stock of organic matter and soil structure. On lands with a slope of more than 3° the area of cultivated crops is reduced or excluded from crop rotation altogether. In case of sowing on sloping lands they are placed in rows across the slope with special soil-protecting measures.
The production of some row crops is particularly profitable, allowing farms to increase their profitability. In addition, locating farms around potato and sugar beet processing plants reduces transportation costs.
Predecessors of row crops
Most row crops are usually placed in the rotation after winter or spring cereals cultivated after better predecessors. For example, corn, potatoes, sugar beets in the Non-Black Soil Zone, the Central Black Soil Zone, and the steppe zone of the European part of Russia are placed after winter cereals cultivated on bare or seeded fallows, perennial grasses, and leguminous crops.
Corn, sunflower, sugar beets, castor beans, potatoes are placed mainly after winter cereals and spring wheat. The best predecessors of row crops are winter crops following bare fallow, then winter crops following seeded fallow. In areas with sufficient moisture content, winter and spring cereals following perennial grasses may be considered as good predecessors.
With a large proportion of row crops in the structure of cultivated areas, subject to high fertility and good fertilization with organic and mineral fertilizers, some of them can be sown on other row crops. For example, in the Non-Black Soil Zone corn can be sown after potatoes, in the Black Soil Zone – corn for silage after sugar beet or sunflower after corn. Leguminous crops, as a more valuable precursor, are used mainly for cereal crops.
The response of row crops to predecessors and the order of alternation in the rotation is different. On well-cultivated and fertile soils, corn, potatoes, and cotton can tolerate repeated sowing for two or more years satisfactorily under high farming techniques.Whereas sunflower and sugar beet, irrespective of the conditions, sharply reduce the yield at repeated sowing.
Despite the satisfactory results of repeated seeding for some row crops, sowing in the same place should be avoided, especially in soils in areas prone to wind and water erosion.
Corn
The best predecessors of corn are winter cereals, spring wheat and barley, leguminous crops, in areas with sufficient moisture also perennial grasses.
In Kuban, corn for grain is often placed after winter wheat, which is cultivated on bare, seeded fallow or half-fallow. In the farm “Leninsky Put” (Slavyansky District, Krasnodar Territory), the highest corn yield was after winter wheat – 5.5 t/ha, and the lowest – after Sudan grass – 2.8-3 t/ha. High yields are also obtained after sunflowers.
In the Non-Black Soil Zone corn is better placed after winter rye, potatoes and grain legumes; in the Volga region and in the Urals – after spring wheat and grain legumes.
Fields with high fertility and good farming techniques are suitable for repeated corn sowing.
Sunflower
Sunflowers have high requirements for moisture (almost 2-3 times more than winter wheat needs). Therefore, in areas of unstable and insufficient moisture, when autumn and winter precipitation does not sufficiently replenish the water consumed by perennial grasses, sugar beet and Sudan grass, sunflower after these predecessors dramatically reduces yields.
Sunflower is best preceded by winter cereals grown on bare or seeded fallow, winter and spring cereals following legumes and row crops, and leguminous crops. Sunflower may be grown after corn in areas with sufficient moisture and a large share of row crops in the crop rotation. In southern areas, it is grown after corn, castor beans, coriander, and tobacco.
Mass proliferation and sensitivity to pests, diseases, and weeds precludes repeated sunflower cultivation and requires a long return period of up to 7-9 years. Particularly damaging to sunflower crops is the root parasite Orobanche. Disease-resistant sunflower varieties were bred to reduce the period of sunflower return, up to and including repeated sowing.
Castor bean
Castor bean (Ricinus communis) are responsive to soil fertility and sensitive to their location in the crop rotation.
The best predecessors of castor bean are winter crops following bare or seeded fallow, as well as after winter and spring cereals following perennial grasses or row crops.
If cultivated well, castor bean may serve as a good predecessor of winter wheat. It is less likely to deplete water reserves compared with sunflowers, and its root system has a good effect on soil structure.
Sugar beet
Sugar beet is characterized by high requirements for soil fertility, preceding crops, and soil moisture reserves. Its root system dries the soil to a depth of 150-200 cm, and harvesting is carried out in late autumn.
Sugar beet sharply reduces the yield of permanent and repeated crops because of nematode infestation, root weevil, beet weevil and other pests. In experiments Myroniv Research Institute of Wheat Breeding and Seed Production permanent cultivation of sugar beet for 7 years led to a decrease in yields from 28.4 to 5.6 t / ha. In the conditions of irrigation in the southern areas, repeated sowing is possible, which does not reduce the yield.
According to the experimental institutions of the Central Black Earth Zone and the North Caucasus, the best for sugar beet predecessors are winter wheat cultivated after bare or seeded fallow; in the zone of sufficient moisture also winter cereals coming after clover, alfalfa or sainfoin.
Row crops as predecessors
Row crops can be classified as valuable predecessors, after which it is possible to cultivate many agricultural plants.
After corn for green forage, early varieties of potatoes, fodder beans, turnips and other early harvested crops, winter wheat, rye and barley give good yields.
However, most row crops are late harvested crops: potatoes, beets, corn for silage or grain, sunflowers and others. Therefore, they are used as predecessors for spring crops – spring wheat, barley, oats, buckwheat, millet, leguminous crops, hemp, flax, etc. After potatoes, corn, sugar beet and others spring wheat yield is on the average by 15-20% higher than after cereals or at repeated sowing.
In the conditions of Bashkortostan the yield of spring wheat after tilled crops was the same as after peas.
According to the All-Russian Flax Research Institute, the flax yield in the Tver Region after potatoes was the same as after perennial grasses, while fiber quality was higher. Spring barley, millet, peas, buckwheat, hemp, and other spring crops respond well to row crops.
Table. Effect of predecessors and fertilizers on grain yield of spring wheat (Amirov, 1996)
| Peas | ||
| Corn | ||
| Sugar beet | ||
| Potatoes | ||
| Winter rye | ||
| Spring wheat | ||
Corn in the conditions of Non-Black Soil, forest-steppe and steppe zones of the European part of Russia can be cultivated repeatedly.
Repeated and permanent crops of potatoes are possible at a high level of agrotechnics and fertilization of the soil. This is confirmed, in addition to experiments, by the practice of its cultivation in household farms, where the dose of organic fertilizers is hundreds of tons per 1 ha and individual care of plants is provided.
Sunflowers can be a precursor to winter crops under conditions of sufficient moisture in southern areas, where their crops are harvested early enough, and the dense stalk suppresses sunflower seed sprouts that crumble during harvesting (windfalls). In general, it is a poor predecessor for many crops because of the great drying of the soil and windfalls, so fallows are introduced after it.
Often, row crops are good precursors to other row crop families. For example, in the Non-Black Soil Zone, potatoes are one of the best predecessors of fodder beets and corn for silage or green fodder; in the forest-steppe zone – for corn for silage, sugar beets, hemp.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Leguminous crops in the crop rotation
The leguminous crops in the crop rotation is a group of crops in the crop rotation that includes such crops as peas, cicer, lentils, lathyrus, vetch, pelushka for seeds, lupine and others. They are of great value as a predecessor because of their ability to accumulate nitrogen in the soil. They are inferior to perennial grasses such as clover and alfalfa in the amount of accumulated nitrogen, but even this amount is enough for many crops on low fertility podzolic soils.
Main article: Leguminous crops
The importance of crop rotation for leguminous crops
There are a number of traditional reasons for the need for crop rotation when cultivating peas or beans. Weed control can be improved by using spring crops, and residual nitrogen improves soil fertility for the following crop. Large-seeded legumes fit well in crop rotations with cereals and can be grown with the same machinery and stored on existing equipment. Vegetable crops are more demanding in terms of machinery, labor and harvesting equipment, but their value as a catch crop and general soil improver remains the same.
The occurrence of soil-borne pests and diseases depends largely on the proximity of pea, bean, or other host crops. Nematode pests may infest peas or horse beans and be soil-borne or, in the case of stem and bulb nematodes, may be introduced into the field through infested seeds. Fungal pathogens that cause downy mildew and fungi involved in the soil root infection complex, such as Fusarium solani f. sp. pisi, Didymella pinodella (syn. Phoma medicaginis var. pinodella) and Aphanomyces euteiches, are likely to increase their intensity with long-term cultivation.
Both peas and beans may be in the same crop rotation, and since there are commonalities between the pest or pathogen and the legume host crop, peas and beans should be classified as the same crop for rotation purposes. The longer the period of absence of host crops that can be provided in a rotation, the less likely it is that pathogen and pest populations will accumulate in the soil.
Currently, in the UK and Europe, the minimum period between large-seeded legume crops is 4 years, during which neither peas nor beans are grown. In practice in the UK, experience has shown that a longer break is useful in reducing the risk of losses from a complex of root diseases.
Some legumes are early spring crops that grow quickly and are harvested early from the fields. Thanks to the early closing of rows and dense covering of the soil surface, legume crops reduce the weediness of fields, being strong competitors, preserve moisture and soil structure, activate microbial processes in the rhizosphere, contributing to the translation of hardly soluble forms of phosphorus in available to plants.
Diseases and pests characteristic of legume crops do not affect crops of cereals and other subsequent crops.
Predecessors of leguminous crops
The best predecessors for legumes are corn and winter wheat. At the state farm “Petrovsky” in the Lipetsk region, the yield of peas after corn was 4.65 t/ha, while after buckwheat, barley and beets for seed – 4.06 t/ha.
Sugar beets, potatoes and millet are good predecessors for peas. For cicer and lathyrus Sudan grass is not inferior as a predecessor to corn, while for spring cereals and winter wheat it is a bad predecessor.
Potatoes, spring and winter cereals are good precursors of leguminous crops in the Non-Black Soil Zone.
In general, leguminous crops in the crop rotation can be well placed on any predecessors, except for repeated and permanent crops, in which their yield decreases sharply, and the susceptibility to specialized diseases and pests increases.
Leguminous crops as predecessors
Due to the short growing season and early harvesting followed by tillage, leguminous crops can be considered good predecessors of winter wheat and winter rye. According to observations, for many regions of Russia, leguminous crops are not inferior to bare and seeded fallow in their influence on the yield of subsequent crops and soil fertility. For example, according to the All-Russian Institute of Legumes and Cereals, the yield of winter wheat in the Orel region for black fallow was 3.35 t/ha, for vetch – 3.40 t/ha, for pea – 3.51 t/ha, for clover fallow – 3.49 t/ha. Under the same conditions, winter rye yield for peas was 3.62 t/ha and for vetch – 3.58 t/ha.
When moving to areas with increasing continentality of climate, peas as a precursor is inferior to bare fallow. According to the NPO “Niva Tatarstan”, the yield of winter rye on black fallow was 3.21 t/ha of grain, and on pea – only 2.67 t/ha. However, the total productivity of the crop rotation section with peas due to the additional yield was higher by 1.1 t/ha, or 13%, compared with the section with bare fallow. Similar data are given by NPO “Don”: the yield of winter wheat after peas decreased by 26.6% compared with bare fallow, but even in this case, the productivity due to the additional yield of peas was approximately equal.
Leguminous predecessors influence the quality of rye and wheat grains by increasing the protein content.
The leguminous crops in the crop rotation are good precursors for long-fibre flax, oats, barley, millet, buckwheat, most row crops – sugar beets, potatoes, corn, sunflowers, tobacco, hemp, vegetable crops. Sowing these crops after leguminous crops allows obtaining the same yields as after winter wheat following the best predecessors.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Peas and beans. Crop production science in horticulture / Antony J. Biddle. 2017. UK.
Perennial grasses in the crop rotation
Perennial grasses in the crop rotation is a a group of crops in the rotation that primarily includes forage legumes – clover, alfalfa and forage cereal grasses – timothy, fescue, ryegrass multiyear, vetch and others. Their qualities as a predecessor are determined by the ability of legumes to accumulate nitrogen in the soil, a complex positive impact on fertility and productivity of subsequent crops.
Strongly developed root system with a large mass of cereal grasses allows to accumulate humus in the soil, positively affecting the balance of organic matter. The mass of plant residues reaches 7-8 t/ha of absolutely dry matter. Often the group of perennial grasses by their influence on fertility and yields of winter cereals and other crops exceeds the seeded and bare fallow on condition of sufficient moisture because of high moisture consumption. Lack of moisture sharply reduces the yield of perennial grasses, leads to thinning and weed infestation. For this reason, perennial grasses are used in areas with sufficient moisture as well as on irrigated lands as predecessors to winter crops. Their effect is maintained on the second and third crops, determines their versatility and diversity of use as a predecessor.
Main article: Perennial grasses
Features of perennial grasses in crop rotations
In the first year, perennial grasses develop slowly and do not yield much. During this period, they form a root system, which is preserved under the cover of the main crop, after harvesting of which grasses continue to vegetate and go under the winter. In the spring of the following year, vegetation resumes. Perennial grasses allow you to make 2-3 mowing operations during the summer. The period of their use may be in field crop rotations 2-3 years, in forage and specialized – 4-5 years and more.
Perennial grasses in the crop rotation are usually sown under the cover of preceding annual grasses or cereal crops or sown simultaneously with early spring crops. Grain-grass seeders are used for this purpose.
Sowing of perennial grasses in the Nonchernozem zone is carried out in spring under the cover of spring and winter cereals. However, with a high yield of cereals up to 3.5-5 t/ha of grain, seeded perennial grasses are oppressed by the cover crop, which leads to their significant thinning. For this reason perennial grasses are sown under the cover of annual grasses, winter crops or a forage mixture.
Perennial grasses in the crop rotation are, in addition to cereals, good precursors for potatoes (in the absence of wireworms), spring cereals, millet, hemp, and cabbage. For fiber flax, clover and some other perennial grasses are particularly valuable precursors, reducing weed infestation, disease and pest incidence and yielding high yields of seeds and flax fiber.
In the eastern areas of the Nonchernozem zone perennial grasses are a good predecessor for spring wheat provided there is no wireworm.
Strong infestation of wireworms makes perennial grasses in the crop rotation unsuitable for use as a precursor for potatoes, corn and spring wheat.
Sowing of row crops – sugar beet, corn, potato, hemp, tobacco and others 1 year after perennial grasses shows good results.
Under irrigated and southern humidified conditions alfalfa 2-3 years of use is a good predecessor of winter crops and rice. In Central Asia, it interrupts the permanent crops of cotton. In these regions, it is possible to sow perennial grasses without cover, and they already give the first crop of fodder mass in the first year of sowing. In this case the year of sowing is the first year of their use.
Moisture is the main influence on the efficiency of perennial grasses. The timing and methods of cutting turf, weight and composition of root and hay crop residues, degree of contamination by diseases and pests, weediness.
Perennial grasses perform an ecological function of soil protection from erosion. Due to the strong herbage, they shelter the soil from intensive atmospheric precipitation and wind. Their powerful root system creates the upper layers of soil strengthened against the destructive effects of water and wind.
Due to accumulation of large amounts of plant and root residues, perennial grasses are an important factor in increasing soil fertility. The accumulated stocks of organic matter from the decomposition of plant residues structure and improve soil fertility indicators, increasing its moisture capacity, aeration, the proportion of available and fixed forms of nutrients, including from applied fertilizers.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Seeded fallow
Seeded (busy, occupied) fallow is a fallow field sown in the spring with a crop and released early. After harvesting the crop, soils are cultivated according to the fallow type and the field is prepared for sowing winter or spring crops. The seeded fallow plays the most important role in increasing grain and fodder production, especially in areas with sufficient moisture.
Crops can be sown in seeded fallows, such as bovine-oat, pea-oat, pea-barley or other mixtures of annual crops, as well as some perennial grasses for hay, green fodder or silage, corn and early potatoes. Such crops are called annual grasses and are harvested for fodder in the phase of budding – the beginning of flowering of the legume component.
The fallow time in the seeded fallow is much shorter than in the bare fallow. They are widespread in zones with sufficient moisture: Non-chernozem and forest-steppe zones, as well as in zones with sufficient moisture in the North Caucasus, Siberia, Central Black Earth zone. In these regions, cultivation of crops intended for fallow (fallow crops), with sufficient moisture does not lead to a decrease in yields of winter cereals sown after fallow, which allows for obtaining additional amounts of green fodder for livestock, hay, silage, potatoes under proper farming techniques.
As a rule, seeded fallows are sown on weed-free fields with sufficient fertilizers. This increases the productivity of the use of arable land and the yield of agricultural products as compared with crop rotations with bare fallows.
Fallow crops must mature early and suppress the growth of weeds. Fallow crops are mainly represented by legume crops.
Types of seeded fallows
Continuous fallow is a seeded fallow in which the fallow crop is a continuous crop, i.e. annual and perennial grasses, cereals, legumes and their mixtures.
Row seeded fallow is a seeded fallow in which the fallow crop is early mature row crops such as early potatoes, in the southern regions – corn, sunflowers for green fodder or silage, etc.
Due to the fact that crops are planted with row spacing of 45-60-70 cm in row seeded fallow, it allows, unlike continuous fallow, summer tillage, which reduces the number of weeds, preserves moisture, maintains favorable air and nutrient regimes of soils.
Sideral fallow is a seeded fallow in which the fallow crop is a siderat (green fertilizer). Most often this role is played by leguminous crops such as clover, lupine, seradella.
Plowing green mass of green manure enriches the soil with organic matter, which during decomposition improves its agrophysical, agrochemical and biological indicators of fertility. Sideral fallows are often used in the zone of sufficient moisture on poor organic matter and light sandy soils. They are also used on heavy clay soils, which contributes to structuring and creation of better friability and water permeability.
Half-fallow is a fallow field left after harvesting cereals, leguminous and some other crops, which is repeatedly tilled by the type of fallow. As a rule, fallowing lasts 2-3 months. Half-fallow is more often used in the steppe regions of European Russia.
Non-fallow predecessors are crops in the rotation with a late harvesting period that do not have a fallow period.
Peculiarities of the use of seeded fallows
In contrast to bare fallows, which are mainly used in conditions of insufficient moisture, seeded fallows are characteristic of conditions of sufficient moisture or irrigation, as well as higher cropping culture (use of fertilizers, modern technologies of soil treatment and plant protection). Winter crops are placed after seeded fallow, which in the Non-Chernozem zone give 5-15% lower yields than after bare fallow, however, due to the products obtained from the fallow crop, the efficiency is generally higher. This is especially noted if legumes, which accumulate nitrogen in the soil, and siderates are used as a fallow crop. For example, in Nizhny Novgorod region winter wheat yield by sideral (lupine) fallow was 0.4 t/ha, or 11% more than by black fallow, by vetch-oat seeded fallow – by 0.46 t/ha, or 12%.
Vetch-oat seeded fallow is often used in the Non-Black Soil Zone, where its efficiency in terms of effect on potatoes and other row crops is comparable to that of bare fallow.
Potato seeded fallow by its effect on the yield of winter crops, as well as on the productivity of the section of the rotation with row crops is comparable with vetch-oat seeded fallow. However, in comparison with bare fallow, the productivity of the section is higher by 23-30%.
In more moisture-deficient conditions, for example, in the Central Black Earth zone, winter wheat yields are 15-20% higher with bare fallow than with vetch-oat fallow. However, even in this case, the efficiency of the section due to the production of fallow crops is higher.
In areas of sufficient moisture in the North Caucasus, seeded fallows of leguminous perennial grasses – clover and sainfoin – allow to obtain the same yields of winter wheat as after bare fallow.
On sandy and sandy loam soils, sideral fallows play an important role. For example, in the Nizhny Novgorod region, lupine sideral fallow reduced weed infestation, improved soil structure, and increased winter rye yields up to 3.91 t/ha. The efficiency of black fallow without manure application in these conditions was 3.56 t/ha, and with the application of 50 t/ha of manure – 4.13 t/ha.
In Priob’ye and Altai, the cultivation of spring wheat after sideral (clovergrass) fallow yielded 2.59 t/ha, after bare fallow – 2.90 t/ha.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Bare fallow
Bare fallow – a field of crop rotation, free of crops during the growing season. Bare fallow is cultivated during the whole warm period of the year, keeping the soil loose, conducting extermination measures against weeds, pests and pathogens of crops, carry out reclamation work. A fallow field does not produce agricultural products, it prepares the soil for cultivation of subsequent crops.
The importance of bare fallow in the crop rotation
Bare fallows allow:
- accumulate moisture, conserve and sustainably use soil moisture;
- mobilize nutrients in the soil;
- to carry out activities to control weeds, pests and pathogens of crops.
The whole complex of agronomic practices allows to improve the fertility of fallow soils and to create optimal conditions for the growth and development of plants, making them the most valuable predecessor for all crops, especially for the most demanding cereals – winter and spring wheat and winter rye.
Bare fallow, on the one hand, leads to intensive decomposition of soil organic matter, on the other hand, enriches it with nutrients in available forms for plants, provided there are no weeds. This is especially important in the deficit of fertilizers, especially phosphorus, which is poor in chestnut and chernozem soils of the steppe zone.
Bare fallow perform a phytosanitary function in controlling weeds, pests and pathogens of crops (for example, defeat wheat root rot decreases by several times), increase soil biological activity, accelerating the mineralization of organic matter.
Bare fallows due to their positive role allow to obtain high sustainable yields of wheat (winter and spring) of good quality, especially in the steppe regions: the Volga region, the North Caucasus, the South-East of Russia, where the wheat yield after a bare fallow increases by 1.5-2 times compared with other predecessors; and in the arid steppe and forest-steppe regions of the Southern Urals, Volga, Trans-Urals, Altai and Western Siberia – by 30-50%.
Types of bare fallows
Bare fallows can be:
- black;
- early;
- late.
Black fallow is a bare fallow, the main tillage of which is carried out in autumn after harvesting the preceding crop.
Early fallow is a bare fallow, the main tillage of which is carried out in spring, in the year of fallow. It is used in areas where the autumn period is short or there is no time to till the soil after harvesting spring crops, for example, in Northern Kazakhstan and Siberia. In addition, leaving stubble, reduces the effect of wind erosion and increases snow accumulation.
Black fallows almost always have an advantage over early fallows, as it allows the accumulation of more moisture due to the fall-winter and spring period, as well as a longer application of extermination measures.
Strip fallow is a black or early fallow in which tall crops such as sunflowers, corn, mustard, and other plants with strong stems are planted in strips. They are most often used in arid steppe areas with strong winds.
Strip fallow performs three functions: snow retention, protection of winter crops from unfavorable conditions in winter in low-snow and arid areas, and soil protection from wind erosion.
The strips are placed across the direction of the prevailing winds, with a distance between them equal to 3-5 times the working width of seeders or 8-24 m. Cultivated crops are sown during fallow cultivation, for example, by cultivators aggregated with seed drills. If the summer sowing dates of the sward (for arid areas – late June – early July), they do not have time to gain sufficient height, which allows to sow winter crops across the sward. Damage to plants by the passage of seeders is relatively small, they have time to strengthen enough before winter and give a stable stem at the onset of frost.
The strips allow to retain even the first snow, while snow rolls can be made only when the snow cover height is 12-15 cm. Increasing the thickness of snow cover contributes to the accumulation of moisture, protecting winter crops from freezing and sharp fluctuations in temperature during the spring period, and preventing wind erosion.
Late, or peasant, fallow was a bare fallow that was used in the three-field farming system of Russia in the spring and summer period for the pasture of cattle. On peasant farms which lacked efforts and means for the simultaneous spring-summer field work and tillage of bare fallow, the late fallow was cultivated only in the second half of summer, before sowing the winter crops. For this reason, its efficiency is much lower than black or early fallow, and it is rarely used in modern agriculture.
Tillage of bare fallow
Deep tillage in a bare fallow allows to increase absorption and retention of moisture of atmospheric precipitation and melt water.
Surface tillage with fallow cultivators allows to keep the top layer in a friable state, which promotes intensification of microbiological soil processes and accumulation of nutrients. Destruction of the surface crust, prevents moisture evaporation from deep layers.
Repeated trimming of weeds with the help of fallow cultivators allows to sharply reduce the infestation of fields, including vicious weeds related to root-shoot and tap-root weeds, provoking their sprouting with the subsequent elimination. The weed seed bank is also greatly depleted.
In addition to agronomic techniques to control weeds and pests, chemical and biological methods are used.
Bare fallow is suitable for the introduction of organic and mineral fertilizers, lime or gypsum soils.
Cereal crops may account for 30-50% of arable land in cereal crop rotations. Less land is allocated to bare fallow, so often repeated seeding is resorted to, the remaining share of cereals is placed on annual and perennial grasses, leguminous, corn for silage and some other crops.
Geographic features
There is a certain geographical regularity in intensity of bare fallow use in crop rotations, in which the decisive role is given to water: as the amount of atmospheric precipitation changes, the leaching regime of soils changes to nonleaching and as the continental climate increases, the share of bare fallow in the cropping pattern increases to 10-20% and more. This increase is observed from west to east and southeast Russia.
Bare fallows allow the accumulation of significant moisture reserves in the upper meter layer, allowing to obtain stable wheat yields, which is especially important in the arid regions of Russia: the Volga region, the steppe zone of the South-East, the North Caucasus, the Trans-Urals, the Southern Urals, Western Siberia, Altai and others.
For example, in the steppe zone 1.5-2.5 times more water is accumulated in the one-meter layer of soil after a bare fallow compared with the non-fallow predecessors. In the forest-steppe zone – up to 1.3-1.4 times, in areas of the Non-Chernozem zone with sufficient moisture there is practically no increase. For example, in Nizhny Novgorod region under winter wheat crops after bare fallow, moisture reserves were the same as after seeded (occupied) fallows (lupine and vetch). There was no significant difference in wheat yield in these fallows (3.83 and 4.1 t/ha).
On the contrary, under the conditions of the dry steppe zone in Western Siberia (Omsk region) reserves of productive moisture in the soil layer after black fallow before sowing of spring wheat amounted to 143 mm with a grain yield of 2.11 t/ha whereas under permanent sowing reserves of moisture were only 76 mm with a yield of 1.1 t/ha.
Bare fallow has a positive impact on soil water regime not only for the first, but also for subsequent crops of crop rotation. For this reason in the steppe zone crop rotations alternating bare fallow with repeated crops of wheat are widespread:
- in the eastern part of the steppe zone of Russia: 1 – bare fallow, 2 – spring wheat, 3 – spring wheat;
- in the European part: 1 – bare fallow, 2 – winter wheat, 3 – winter wheat;
- in the Volga region (transition zone): 1 – bare fallow, 2 – winter wheat, 3 – spring wheat.
Under the conditions of unstable moisture in the steppe zone of the North Caucasus (Krasnodar and Stavropol regions, Rostov region), the reserve of moisture in the upper 20 cm layer before sowing is of great importance for stable high yields and good overwintering of winter wheat. Bare fallows allow to increase moisture reserve by 15-25% in comparison with non-fallow predecessors.
In order to increase moisture reserves due to melt water, I apply strips in the fallow field. For example, in Altai Krai, the strips allow increasing the thickness of snow cover by 3 times, which contributes to increasing moisture reserves by 20-25%.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Building of crop rotation
Building of crop rotation is the placement of crops and fallows in certain patterns, taking into account the impact of preceding crops on growth, development and yield of subsequent, as well as the influence of physical, biological and chemical indicators of soil fertility.
For this purpose, despite the diversity of biological properties and cultivation technologies, it is customary to combine crops into groups according to their similar qualities as predecessors and similar impact on fertility indicators.
Crop and fallow grouping in crop rotations
The modern grouping consists of the following groups:
- bare fallows,
- seeded fallows,
- perennial grasses,
- leguminous crops,
- row crops,
- technical non-row crops,
- winter cereal crops,
- spring cereal crops,
- intermediate crops.
The groups are arranged in descending order of the quality of predecessors. That is, the best qualities are bare and seeded fallows. Cereal crops are the worst predecessors.
To assess the crops as precursors the following criteria are taken into account:
- influence on agrophysical, biological and agrochemical indicators of soil fertility and water regime;
- the effect of the predecessor on the growth, development, yield and its quality of subsequent crops;
- soil-protective and ecological function of the predecessor;
- impact on phytosanitary condition of soil;
- influence on the overall productivity of the crop rotation.
The generalizing evaluation criterion is the effect of the predecessor on the yield of subsequent crops and the productivity of the rotation as a whole.
The main principle of crop placement in the rotation is to rotate crops so that each successive crop corresponds to the best predecessor. The most demanding crops should be placed after the best predecessor and at the same time be a good predecessor for the following ones.
Section of a crop rotation is a part of a crop rotation consisting of 2-3 heterogeneous crops, including fallow. For example: 1 – bare fallow, 2-3 – winter wheat; 1 – potatoes, 2 – spring wheat; 1 – first-year clover, 2 – second-year clover, 3 – flax; 3 – barley or oats; 1 – grain legumes, 2 – winter wheat, 3 – spring wheat; 1 – sideral fallow, 2 – winter rye; 1 – corn for silage, 2 – winter wheat.
Crop rotation is composed of separate sections, and it may be shifted in the direction of predominance of grain or row crops.
Any section starts with the best preceding crop: fallow, grain legumes, row crops, or grasses. As a rule, the rotation does not start with grain crops, flax, rice.
When building of crop rotations it is necessary to avoid repeated sowing of crops for more than 2 years. An exception is grain crop rotations on fertile unweeded fields after a clean fallow. In this case, 3-year repeated sowing of cereals, preferably of different species, is allowed.
Sunflowers should not be sown after perennial grasses, sugar beets and Sudan grass, nor vice versa, because of the strong drying of deep soil layers, where the root system of these crops is located.
It is inexpedient to use repeated sowing of legumes, because the nitrogen accumulated in the first year is not used in the second year, while cereals, on the contrary, have a great need for nitrogen. Legumes and row crops are good precursors for almost all crops, so do not place bare and seeded fallows after them, and vice versa, including the fact that after row crops the soil in a bare fallow is strongly dispersed. In areas threatened by wind and water erosion, for the same reason, the repeated sowing of row crops is not used.
Perennial grasses, as a rule, are placed under the cover of winter, spring grain crops or annual grasses. This is due to the fact that perennial grasses develop slowly in the first period of their life and do not give satisfactory yields. If they are sown in the same field as the cover crop, they form a root system, and after harvesting cereals in the next year provide a good yield.
Perennial grasses in the year of sowing show high sensitivity to weeds, due to which they are placed in the best sections. For example: 1 – sugar beet, 2 – barley with underplanting of perennial grasses; 1 – bare fallow, 2 – winter wheat with underplanting of perennial grasses; 1 – seeded potato fallow, 2 – winter rye with underplanting of perennial grasses; 1 – bare fallow, 2 – spring or winter wheat, 3 – spring wheat with underplanting of perennial grasses.
As a rule, fields with the worst predecessors, such as oats, are assigned for bare fallow.
When building of crop rotation it is necessary to take into account not only the effect of the predecessor on the first crop, but also its effect on subsequent crops.
In order to evaluate the predecessors, the following should be taken into account:
- irrigability of the fields;
- previous weed infestation of fields;
- Infestation of soil and plant residues by pests and pathogens;
- technology of cultivation of the preceding crop;
- impact of the preceding crop on agrophysical, agrochemical and biological indicators of soil fertility;
- previous erosion state of the fields and influence of preceding crops and crop rotation as a whole on it.
Types of fallows
Different types of fallows are considered the most valuable predecessors in terms of their effect on yields for all subsequent crops in the crop rotation.
Fallows are divided into two types and subtypes:
- bare:
- black;
- early;
- late;
- seeded:
- row crop;
- continuous;
- sideral.
Black and early fallow can have a variation, the coulis fallow.
Semi-fallow fields are distinguished separately.
The efficiency of fallow fields strongly depends on soil and climatic conditions, fertilizers and plant protection system. In modern farming systems with advanced tillage systems, crop rotations without fallow fields can be more productive.
Principles of building of crop rotations
Principle of adaptability
The principle of adaptability implies the use of crops in the rotation, adapted to local soil and climatic conditions and the planned structure of the sown areas of a particular farm.
The principle of biological and economic feasibility
The principle of alternation of crops
The principle of alternation of crops provides for an annual change of crops belonging to different economic and biological groups and differing in biology and cultivation technology. The most striking classic example of crop rotation is the Norfolk rotation: cereals – 50%, row crops – 25%, legumes – 25%.
The principle of periodicity
The principle of periodicity implies the need to observe the period of return of the same crop to its former place of cultivation. For most of them this period is 2-3 years, for some – 5-7 years or more.
| Cereals (wheat, rye, barley, oats) | |
| Millet, buckwheat | |
| Corn | |
| Legumes (peas, vetch, china) | |
| Lupine | |
| Potatoes | |
| Sugar beet | |
| Flax fiber | |
| Sunflower | |
| Perennial grasses | |
| Forage, root crops | |
| Tobacco | |
| Rapeseed |
The principle of compatibility and self-compatibility
The principle of compatibility and self-compatibility provides for the possibility of using as the main crops the predecessors of the same economic and biological group or their re-seeding.
For example, sowing winter cereals after spring cereals, oats after spring wheat or after barley, etc., as well as the repeated sowing of spring or winter wheat after bare fallow, repeated sowing of potatoes, corn, rice under special conditions of agricultural engineering. According to this principle it is not allowed to place plants of the same family after each other.
The principle of compacted use of arable land
The principle of compacted use of arable land defines the inclusion of intermediate crops in the rotation in order to increase the efficiency of arable land use.
It is implemented in conditions of intensive farming to organize the conveyor belt of green forage production, as well as sideration. In the conditions of southern areas, intermediate crops allow getting two crops of grain, tuber crops or other products.
Principle of specialization
The principle of specialization determines the possibility of scientifically justified maximum saturation of crop rotation with one crop or one economic and biological group. It is realized in the conditions of intensive farming in the construction of specialized crop rotations.
Building of crop rotations
All principles of building of crop rotations are interconnected with each other. The scheme of alternation must meet the requirements of the tasks of a particular enterprise for the production of agricultural products, taking into account the reproduction of soil fertility and maximize the profitability of production.
When building any crop rotations, an important place is the knowledge of the best predecessors for the main crops, the possibility of their use in specific soil and climate conditions and the provision of the company with means of production: machinery, fertilizers, seeds, plant protection, labor resources, etc.
Table. Predecessors of major crops (generalized)
| Winter cereals (rye, wheat, barley) | Bare fallows, perennial grasses, seeded fallow, legumes, corn for silage and green forage, winter cereals |
| Spring wheat | Bare fallows, row crops, perennial grasses, seeded fallow, legumes, winter cereals |
| Oats, spring barley, buckwheat | Row crops, legumes, winter cereals, spring wheat, technical non-row crops |
| Millet | Row crops, legumes, winter cereals after fallows or perennial grasses |
| Peas, lupine, vetch, lentils, soybeans and other legumes | Row crops (except legumes), winter and spring cereals |
| Potatoes | Winter cereals, leguminous crops, perennial grasses, row crops, spring cereals |
| Sugar beet | Winter cereals, leguminous crops, potatoes, spring wheat |
| Corn | Winter cereals, potatoes, legumes, spring wheat, barley, oats |
| Sunflower | Winter cereals, leguminous crops, corn, coriander |
| Flax fiber | Perennial grasses, legumes, potatoes, corn for silage, winter crops after perennial grasses |
| Hemp | Perennial grasses, legumes, row crops |
| Rice | Alfalfa, leguminous crops, corn, winter cereals |
| Tobacco | Winter cereals, perennial grasses, leguminous crops, corn |
| Cottonwood | Alfalfa, corn, leguminous crops |
| Perennial grasses | Sowing under spring cereal crops, under annual grasses, under winter cereals or sowing after row crops or cereals |
| Annual grasses | Spring cereals, row crops |
| Forage root crops | Winter and spring cereals, corn, potatoes |
| Intermediate crops | Winter and early spring cereal crops, annual forage grasses and other crops harvested early |
In the above list of predecessors, the main crops are arranged in descending order of their value. However, under specific conditions, the priority of predecessors may vary. For example, in arid areas perennial grasses cannot be classified as good predecessors of wheat because of soil drying, while in conditions of sufficient moisture they are not inferior to the effectiveness of seeded fallows.
When making schemes of alternation tend to place the most valuable and demanding crops on the best predecessors, guided by the principles of building of crop rotations.
Another example of the relativity of this order is that winter wheat following perennial grasses may be the best preceding crop for buckwheat or millet, in contrast to row crops that are not provided with a sufficient level of agrotechnics and following cereals. Also, not all row crops may be the best preceding crop for spring wheat. For example, sunflowers or sugar beets are less valuable precursors than leguminous crops or winter wheat with bare fallows because of severe soil desiccation. In addition, sunflowers strongly contaminate crops with fallen seeds, which makes them an unacceptable predecessor for cereal crops.
After determining the scheme of alternation, develop the technology of growing crops for each field. For this purpose they specify terms and methods of tillage and fertilizer application, their types and rates of application, system of plant care, measures to control pests, diseases, weeds, etc.
When planning crop rotations by area, the composition of soils and soil differences, the impact of relief elements on plants and other natural, soil-climatic, organizational and economic features are taken into account. Fields on sloping lands are located across the slope, so that plowing, cultivation, sowing and other techniques to be carried out across the slope, preventing washout and erosion of the soil.
At agricultural companies such types and species of crop rotations are introduced, which most fully meet the natural conditions, farm specialization, scientifically justified structure of sown areas, requirements for the reproduction of soil fertility and growth of crop yields.
No less important is the organizational placement of production and auxiliary areas, their remoteness from settlements and water bodies. For example, the remoteness of silage and fodder crops from storage sites and livestock farms.
It is necessary to provide the most convenient conditions for the use of tractors and machinery to reduce the economic and resource costs of field work. Optimal building of crop rotations allows to distribute the terms of field work in time than in monoculture, which reduces the load on machinery and workers.
The placement of crops in the crop rotation also takes into account the requirements for the timing and methods of sowing, tillage, crop care and harvesting.
Rotation
The rotational table is a guide for the placement of crops on the fields for the next rotation. It serves as a basis for the implementation of systems of tillage, fertilization, plant protection, varietal change, soil protection against erosion, irrigation and other components of cultivation technology.
When implementing the planned rotation of crop rotations, various deviations from the established order of alternation are possible. The reasons for such deviations can be numerous, they are associated with the influence of weather, organizational and economic, soil and other conditions. For example, due to unfavorable conditions of overwintering the crops of winter wheat died. In this case a decision is made to plow the field and sow spring wheat, barley, oats or others in place of winter wheat. If perennial grasses die for the same reason, annual grasses are planted in their place, corn is replaced by other silage crops, etc. Adjustments can also be made for economic reasons – lack of fuel, lack of seed, changes in market conditions, etc.
Substitution of crops within their economic and biological group does not refer to the violation of crop rotation, but indicates its flexibility if necessary within the originally laid structure of cultivated areas, which is especially important in a market economy.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.
Classification of crop rotations
Classification of crop rotations is a systematic representation of the diversity of crop rotations, based on the differences of production purpose and structure of cultivated areas.
The main provisions of the classification
The classification of crop rotations is based on two main features:
- production purpose – the main type of agricultural products, such as grain, fodder, technical raw materials, vegetables, etc. Three types are distinguished – field, forage and specialized;
- structure of sown areas, or the proportion of the main groups of crops, which differ in biological properties and technology of cultivation, the impact on fertility. According to this feature, there are more than 10 species belonging to different types. For example, cereals, flax, potatoes, etc.
In addition to the above-mentioned features, crop rotations are subdivided depending on the number of fields into three-, four-, five-, and six-field ones, etc. The number of fields is determined by a number of factors. For example, in the steppe regions of Siberia and Trans-Ural, where a small number of crops are cultivated, crop rotations with a small number of fields prevail – four-, five- and six-field. In the south of Russia, where many crops are grown, multi-field crop rotations including up to 12 fields are common.
On large farms, several crop rotations may be introduced with different purposes, which allows to optimize organizational and production processes and to increase the efficiency of the arable land use. For example, crop rotations with different structures of areas and different directions can be introduced: beet and corn crop rotations.
In some cases, a withdrawal field is introduced, which is temporarily excluded from the general alternation of crops.
Depending on soil and climatic conditions in different regions of the country, different species may prevail. For example, flax and flax-potato rotations are more often used in the Non-Black Soil Zone, and beet and winter wheat rotations in the south of the country.
Types/subtypes and species of crop rotations:
- Field:
- universal: cereal-fallow, cereal-fallow-row, cereal-row, cereal-fallow-grass, cereal-grass, cereal-grass-fallow-row, cereal-grass-row (fruit-changing), grass-row, row, fallow-row, sideral;
- specialized (grain, flax, beet, potato): cereal-fallow, cereal-fallow-row, cereal-grass, cereal-grass-row (fruit-changing), grass-row, row, etc.
- Forage:
- on-farm: cereal-grass-row (fruit-changing), grass-row, row, cereal-grass;
- hay-and-pasture: grass fields (many grass fields), cereal-grass, grass-row.
- Specials:
- vegetable, vegetable-feed, vegetable-gourd, and gourds: row, grass-row, fallow-row, cereal-fallow-row;
- rice crops: cereal-grass, cereal-row;
- hemp: row, cereal-grass-row (fruit-changing), cereal-fallow-row;
- tobacco crops: row, cereal-grass-row (fruit-changing), grass-row;
- strawberry and fruit nursery: grass-row, fallow-row, sideral;
- medicinal and essential-oil crops: cereal-fallow-row, cereal-grass-row (fruit-changing), fallow-row;
- soil-protective: grass fields, cereal-grass.
Types of crop rotations
Field crop rotations
Main article: Farming: Field crop rotations
Field crop rotation is a crop rotation designed for the production of grain, industrial or forage crops. They are subdivided into universal and specialized subtypes.
Universal field crop rotation – crop rotation, in which most of the arable land accounted for cereals, the rest – for technical and forage crops, in arid areas – also in bare fallow.
Specialized field crop rotation is a crop rotation with a maximum saturation of fields with one crop and crops of one group. For example, in many regions of Russia specialized grain crop rotations with a share of grain and leguminous crops up to 75-85% are widespread. The share of sugar beet in specialized beet crop rotations is up to 30%, and in irrigated conditions – up to 40% of arable land.
In specialized potato crop rotations, under high fertility conditions, potatoes may account for up to 40% of the arable area.
Forage crop rotations
Main article: Farming: Forage crop rotations
Fodder crop rotation is a crop rotation designed mainly for the production of coarse, succulent and green fodder. Most of the arable land is occupied by different types of fodder crops. They are subdivided into on-farm and hay-and-pasture fodder crop rotations.
On-farm fodder crop rotation is a crop rotation whose main purpose is the production of succulent and green fodder, and is located near livestock farms. They are also called root crops and silage in the case of specialization of production of succulent root crops and silage mass. Location near farms reduces the cost of transporting the mass of forage.
Hay-and-pasture fodder crop rotations are crop rotations designed to produce hay, haylage, and livestock grazing. They are dominated by perennial and annual grasses. It is often used in the cultivation of natural forage lands, introducing multifield alternation of meadows and pastures.
Field, forage, and sometimes special crop rotations can be used for the production of feed grain.
Special crop rotations
Main article: Farming: Special crop rotations
Special crop rotation is a crop rotation designed for cultivation of crops requiring special agrotechnics and special conditions. Special crops include vegetables, cucurbits, medicinal plants, essential oil crops, hemp, tobacco, rice, etc. Requirements for special conditions are associated with biological features of their cultivation, such as placement in areas of high soil fertility, availability of irrigation systems, the introduction of high doses of organic and mineral fertilizers, and peculiarities of care and protection of plants. They are divided into eight subtypes.
All types of crop rotations can be referred to as specialized if the share of the main crop or biologically related group of crops in the structure of the sown area is allocated to the maximum allowable share.
A separate place in specialized crop rotations is given to soil-protecting sub-type.
Soil-protective crop rotation is crop rotation, the main purpose of which is to protect soil from wind and water erosion with simultaneous production of agricultural products.
For example, on sloping lands with a steepness of 5-7°, soil-protecting crop rotations with cultivation of perennial and annual grasses (grass-field species) or with partial introduction of winter cereals (grass-grain species) are introduced to protect the soil from water erosion. Due to soil covering by perennial grasses during the year and a powerful root system, they protect the soil from water and wind erosion. In the steppe zone in soil-protecting crop rotations, a strip arrangement of perennial grasses, crops and fallow is used across the direction of the prevailing winds.
Species of crop rotations
Types and subtypes of crop rotations can refer to different species. The following species are used in Russia:
- cereal-fallow;
- cereal-fallow-grass;
- cereal-fallow-row;
- cereal-grass;
- cereal-row;
- cereal-grass-fallow-row;
- cereal-grass-row; (fruit-changing);
- grass-row;
- row crop;
- grass fields;
- sideral;
- grass-cereal;
- fallow-row.
Cereal-fallow
Cereal-fallow crop rotation – crop rotation, in which the predominance of cereals of solid crops and bare fallow fields are used.
For example: 1 – bare fallow, 2-3 – spring wheat, 4 – barley or oats.
Cereal-fallow crop rotations have been used in Russia since the XIV-XV centuries. They were the basis of the three-field system of farming: 1 – fallow field, 2 – winter cereals, 3 – spring cereals.
In modern agriculture, cereal-fallow crop rotation is the basis of soil-protection systems in the arid steppes of the Southern Urals, Altai, Western Siberia and other steppe regions of eastern Russia. In a harsh continental climate with a short dry summer period in the absence of leguminous and row crops, bare fallow is the only good precursor for sowing spring wheat. They allow for sustainable yields of this crop due to the accumulation of soil water and effective weed control.
Under these conditions short three-, four- and five-field grain fallow crop rotations of spring wheat with repeated sowing, interrupted by oats or barley in a five-field fallow: 1 – bare fallow, 2-3 – spring wheat, 4 – barley, 5 – spring wheat are common.
Cereal-fallow-row
Cereal-fallow-row crop rotation – crop rotation with the predominance of cereals of continuous sowing, alternating with bare fallow and row crops. Cereals may account for up to 70% of the arable area, and with corn planted to grain and more.
Cereal-fallow-row crops emerged on the basis of cereal-fallow crops and are improved cereal multifield crop rotations, numbering up to 10-12 fields. They are widespread in semi-arid steppe and forest-steppe regions of European Russia: in the Volga region, the North Caucasus and South-East, in the southern part of the Central Black Earth zone.
A typical example is a ten-row rotation of one of the enterprises in Volgograd region: 1 – bare fallow, 2 – winter wheat, 3 – corn for grain, 4 – spring wheat, 5 – barley, 6 – peas, 7 – winter rye, 8 – spring wheat, 9 – millet, 10 – sunflower.
An example of a cereal-fallow-row crop rotation used in the unstable moisture zone of the Stavropol Territory: 1 – bare fallow, 2 – winter wheat, 3 – winter wheat, 4 – corn for grain, 5 – sunflower, 6 – pea-oat mixture for green fodder, 7 – winter wheat, 8 – winter wheat, 9 – corn for grain, 10 – barley.
In the semiarid steppe regions of the Southern Urals and North Caucasus, and in the Middle and Lower Volga region a simplified cereal-fallow-row crop rotation with a shorter rotation is used: 1 – bare fallow, 2-3 – cereals, 4 – row crops, 5-6 – cereals.
The disadvantage of this species with a high proportion of bare fallow and row crops is poor soil protection from erosion. Therefore, when it is used, special measures aimed at protection in steppe areas – from wind erosion; on slopes with an angle of more than 1.5-2° – from water erosion.
Cereal-row
Cereal-row crop rotation is a crop rotation in which cereals are dominated by row crops, replaced by row crops. They are common in areas of sufficient moisture with grain production, where there is no need for bare fallow, for example, in the Central Black Earth zone (with sufficient moisture), the North Caucasus, the Non-Black Earth zone and the Far East.
In them, row crops are replaced by cereals, groats or legumes going one or two years in a row. For example, for potato crop rotations on light soils of the Non-Chernozem zone the following alternations are used:
1 – early potatoes, 2 – winter rye, 3 – lupine for grain, 4 – potatoes, 5 – oats;
1 – leguminous crops, 2-3 – winter wheat, 4 – corn, 5-6 – winter wheat, 7 – sugar beet, 8 – barley, 9 – corn, 10 – winter wheat;
Far Eastern soybean crop rotation: 1 – soybean, 2-3 – wheat, 4 – soybean, 5 – barley.
Also, as in the case of the cereal-fallow-row, cereal-row crop rotation requires special measures to protect the soil from erosion.
Cereal-fallow-grass
Cereal-fallow-grass crop rotation – crop rotation with the predominance of cereal crops, alternating with bare fallow and perennial grasses. They may include fields of technical non-row crops, for example, fiber flax.
Cereal-fallow-grass crop rotation – crop rotation with the predominance of cereal crops, alternating with bare fallow and perennial grasses. They may include fields of technical non-row crops, for example, fiber flax.
An example is the Volokolamsk eight-field: 1 – bare fallow, 2 – winter cereals with undersowing of clover, 3-4 – clover, 5 – fiber flax or spring cereals, 6 – bare fallow, 7 – winter cereals, 8 – spring cereals.
Cereal-fallow-grass crop rotation are improved cereal crop rotations used in the northern regions of the European part of Russia.
In the north-eastern part of the Nonchernozem zone eight-field alternation is used: 1 – bare fallow, 2 – winter rye, 3 – barley with undersowing of perennial grasses, 4-5 – perennial grasses, 6 – winter rye, 7 – oats, 8 – barley.
Cereal-grass
Cereal-grass crop rotation – crop rotation with the predominance of cereals of continuous sowing, the rest of the arable area which is occupied by perennial and annual grasses.
They are also a type of improved cereal crop rotations. An example of the transition from a three-field system to a more perfect farming system is the same Volokolamsk eight-field, in which two fields are allocated for perennial grasses, the other two – under bare fallow.
In the future, bare fallows were replaced by seeded fallows, with an increasing proportion of perennial grasses.
In modern agriculture, cereal-grass crop rotations are used in the Non-Chernozem zone, in farms with a small share of row crops or developed separate on-farm crop rotations. For example, 7-field crop rotations: 1 – seeded fallow, 2 – winter cereals, 3 – spring cereals with undersowing of perennial grasses, 4-5 – perennial grasses, 6 – winter cereals, 7 – spring cereals.
In the 8-field a field of fiber flax is added between perennial grasses and winter cereals: 1 – seeded fallow, 2 – winter cereals with undersowing of perennial grasses, 3-4 – perennial grasses of the 1-2nd year of use, 5 – fiber flax, 6 – winter cereals, 7 – spring cereals.
In the case of replacing the seeded fallow to bare fallow, which in recent years has become more practiced, seven-field crop rotation turns into a cereal-fallow-grass crop rotation.
Due to the fact that perennial grasses and winter cereals with good soil-protecting properties are used in cereal-grass rotation, and they account for most of the arable land, they can be successfully used on sloping lands with steepness up to 5-7° in order to protect against erosion.
Cereal-fallow-grass-row
Cereal-grass-fallow-row crop rotation is a crop rotation in which cereals alternate with bare fallow, perennial grasses and row crops. Their structure of cultivated areas is close to the cereal-grass-row crop rotation, but there is a field of bare fallow: 1 – bare fallow, 2 – winter wheat, 3 – potatoes, 4 – barley with undersowing of perennial grasses, 5-6 – perennial grasses, 7 – winter wheat, 8 – oats.
Cereal-grass-fallow-row crop rotation is the result of further improvement of cereal-fallow three-field crop rotation. Replacement of bare fallow to seeded fallow and the introduction of another field of row crops turns it into a classic scheme of cereal-grass-row (fruit-changing) crop rotation.
Cereal-grass-row (fruit-changing) crop rotation
Cereal-grass-row (fruit-changing) crop rotation is a crop rotation in which cereals account for up to half of the arable area, alternating with row crops and legumes.
For the first time it was used in England in the county of Norfolk with the following scheme of rotation: 1 – row crops, 2 – spring cereals with undersowing of clover, 3 – clover, 4 – winter cereals. Grain crops occupy 50%, legumes and row crops – 25% each, which allows optimal maintenance of the principle of crop rotation, i.e. such an order of alternation in which the fields of crops that differ sharply in biology and cultivation technology, constantly replace one another.
In the cereal-grass-row rotation the cultivation of cereals is interrupted by row crops from another family and with a different technology of cultivation, and then by legumes, which are the best predecessors of cereals.
The Norkfolk crop rotation is a combination of two-field links in which one field is devoted to cereals and the other to row crops or legumes. The transition to the Norkfolk crop rotation from a cereal fallow three-field rotation was associated with the replacement of bare fallow with a legume crop (clover) and the inclusion of a row crop (turnip) between the re-cultivation of two cereal crops.
This change of cereal-fallow three-field to cereal-fallow-row four-field crop rotation was a big step towards the intensification of farming, which was a new stage in the development of farming.
In modern farming systems, the classical scheme of cereal-fallow-row was expanded with a set of tilled and leguminous crops and rotation was increased. Legumes are often represented by perennial grasses in mixtures with biennial cereals or several fields of legumes. The crop rotation may include 2-3 fields of row crops – corn, potatoes, sugar beets, etc. The duration of rotation of modern variants can reach 8-12 years.
Cereal-fallow-row crop rotations are used in some areas of the Central Black Earth and Non-Black Earth zones, in the irrigated lands of southern Russia, where the agronomic effect of 2-3 years of alfalfa use is well manifested.
An example is the eight-field field, common in the Nonchernozem zone: 1-2 – perennial grasses, 3 – winter cereals, 4 – potatoes, 5 – spring cereals or leguminous plants, 6 – winter cereals, 7 – corn for silage, 8 – spring cereals with undersowing of perennial grasses.
In the forest-steppe zone of the European part of Russia and in the Kuban areas with sufficient moisture a typical example is: 1 – seeded fallow, 2 – winter wheat, 3 – sugar beet, 4 – spring cereals with undersowing of perennial grasses, 5 – perennial grasses, 6 – winter wheat, 7 – corn for grain and silage, 8 – peas, 9 – winter wheat, 10 – corn for grain, 11 – sunflower, millet.
Cereal-fallow-row crop rotations, including 2-3 fields of row crops, have low soil-protective function, so on slopes steeper than 2° it is necessary to apply a system of special soil-protective measures.
Grass fields
Grass-field crop rotation is a crop rotation in which most of the arable land is occupied by perennial grasses. The remaining part is occupied by annual grasses, sometimes – grain forage crops.
Grass-field crop rotation is a crop rotation in which most of the arable land is occupied by perennial grasses. The remaining part is occupied by annual grasses, sometimes – grain forage crops.
This type is used in forage crop rotations and forms the basis of an intensive meadow-pasture farming with the following scheme of rotation: 1-5 – perennial grasses, 6 – annual grasses with undersowing of perennial grasses.
If production of green and roughage is combined with production of forage or with cultivation of non-row technical crops, the following scheme of rotation is possible: 1-4 – perennial grasses, 5 – cereals or fiber flax, 6 – annual grasses, 7 – spring cereals with undersowing of perennial grasses. This type is close to grass-cereal.
Grass-field crop rotations have excellent soil-protective properties, so they are used in areas with wind and water erosion.
In them perennial grasses in the first and second years of use are intended for hay, in subsequent years – for cattle grazing.
Grass-cereal
Grass-cereal crop rotation is a rotation in which half or most of the arable land is allocated to perennial and annual grasses, and the rest to cereal crops.
For the Nonchernozem zone we use the following crop rotation: 1-4 – perennial grasses, 5 – winter wheat, 6 – oats, 7 – barley, 8 – annual grasses with undersowing of perennial grasses. The rotations are aimed at production of coarse fodder and grain forage and are complementary to on-farm and hay-and-pasture forage crop rotations.
Crop rotations with perennial grasses are widespread in the Non-Chernozem zone in areas with sufficient moisture. With a low level of intensification, they have very good soil-protecting properties.
Grass-row
Grass-row crop rotation is a crop rotation that alternates row crops and perennial grasses. As a rule, perennial grasses occupy 2-3 or more fields.
They are used as field crop rotations under irrigated conditions in the southern regions of Russia for the production of grain, technical or forage crops: 1-2 – alfalfa, 3 – sugar beet, 4 – corn for grain, 5 – leguminous plants, 6 – sugar beet, 7 – barley with alfalfa underplanting.
In the south-western part of the Non-Black Soil Zone on peat-bog soils the following alternation schemes are used:
- 1-3 – perennial grasses, 4 – winter cereals, 5 – sugar beets, 6 – potatoes, 7 – corn, 8 – corn and leguminous plants, 9 – annual grasses with underplanting of perennial grasses;
- 1-2 – perennial grasses of the 1-2nd year of use; 3 – corn; 4 – potatoes; 5 – root crops; 6 – silage crops; 7 – annual grasses with replanting of perennial grasses.
Vegetable-forage
Vegetable-forage crop rotations – special crop rotations used in vegetable production, including vegetable crops and perennial grasses.
For example: 1-2 – perennial grasses, 3 – cabbage, 4 – tomato, 5 – cucumber, 6 – onion, 7 – table root crops, 8 – annual grasses with undersowing of perennial grasses.
Row crop rotation
Row crop rotation is a crop rotation in which a large proportion of the cultivated area is occupied by row crops. It is the most intensive type of crop rotations, with a high degree of saturation with row crops, they continuously replace each other for several years. Thanks to the species difference of row crops, it is possible to avoid the negative phenomena arising from repeated and permanent sowing of the same type of plants.
Row crop rotations first appeared in the late 19th and early 20th centuries in some farms of Russia specializing in the production of factory sugar beet, vegetables, and factory potatoes. In Central Asia, they were the basis of cotton growing.
At present, they are used in areas with sufficient moisture and on irrigated land. For example, in the Central region of Krasnodar Krai the following scheme of alternation is used:
- 1 – corn for grain, 2 – sunflower, 3 – leguminous crops, 4 – winter wheat, 5 – sugar beet, 6 – corn for grain, 7 – corn for silage, 8 – winter wheat, 9 – sugar beet, 10 – winter barley with stubble corn;
- 1 – corn for silage, 2 – winter wheat, 3 – sugar beet, 4 – corn for grain, 5 – winter wheat, 6 – sunflower, 7 – winter wheat, 8 – sugar beet, 9 – corn for grain, 10 – barley.
Under the irrigated conditions of the South-East, North Caucasus and other southern regions of Russia the majority of vegetable crop rotations are row crop rotations. In the Nonchernozem zone, in areas with sufficient moisture in the forest-steppe zone, on-farm forage crop rotations have a short rotation with a predominance of row crops: 1 – annual grasses, 2 – forage root crops and potatoes, 3 – corn for silage, 4 – sunflower for silage.
The big disadvantage of row crop rotations is very poor soil-protecting functions, for this reason they should be placed on flat lands or with a weak slope, provided soil-protecting measures are used.
Sideral crop rotation
The sideral crop rotation is a crop rotation in which one or more fields are allocated for sideral crops. They are used in poor sandy and sandy loam soils, the share of which, for example, in the Non-Chernozem zone can be about 30% of the arable area.
An example of a sideral crop rotation: 1 – lupine for green fertilizer (siderat), 2 – winter rye, 3 – potatoes, 4 – oats.
In the southern areas of the Non-Black Soil Zone sideral crop effect can be enhanced by additional crop sideration (introduction of intermediate sideral crops) in combination with the use of straw as an organic fertilizer:
- 1 – annual lupine for green fertilizer, 2 – winter rye, 3 – potatoes, 4 – annual grasses for feed, 5 – winter rye + crop siderat (rape, mustard white, etc.) with straw fertilizer, 6 – corn for silage, 7 – oats;
- 1 – lupine, 2 – winter rye, 3 – spring wheat, 4 – seradella, 5 – winter wheat, 6 – potatoes, 7 – oats or barley.
Annual and perennial lupine, seradella, clover, cloverleaf, white mustard, oil radish, rape and other legumes can be used as green crops.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.
Scientific basis of crop rotations
Scientific basis of crop rotations is a complex of reasons based on the experience and knowledge accumulated by science, stipulating the necessity of crop rotation.
D.N. Pryanishnikov first summarized these reasons on the basis of works devoted to:
plant nutrition – the humus theory of A. Thayer, the theory of mineral nutrition by J. Libich;
formation and accumulation of harmful substances in the soil under no-till crops by R.K. Maker, A. de Candolle et al;
symbiotic ability of leguminous crops and different influence of plants on soil properties, first of all on structure by P.A. Kostychev and V.R. Williams.
Causes of alternation are divided into:
- physical;
- chemical;
- biological;
- economic.
Many years have passed since D.N. Pryanishnikov’s generalization, the knowledge in this direction has significantly expanded, however, the four groups of causes highlighted by him remain relevant.
Crop attitudes towards permanent and repeated crops
Today’s tough market conditions dictate the requirement for the possibility of flexible changes in the structure of sown areas, both by changing crop rotations, and the use of repeated and permanent crops. Therefore, profound knowledge in the theory and practice of crop rotation in this direction allows agronomists and managers of enterprises to increase the sustainability of agribusiness.
According to the results of long-term experiments, different attitudes of crops to permanent crops have been established.
Grain crops, especially winter crops, as well as in the absence of fertilizers show the greatest sensitivity to permanent crops. Yield gains from the introduction of crop rotation are greater than from fertilizer and range from 50 to 73%.
Table. Effect of fertilizers and crop rotation on crop yields, t/ha[1]Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. - M.: Publishing house "Kolos", 2000. - 551 p.
| Winter wheat | ||||||
| Spring wheat | ||||||
| Winter rye | ||||||
| Barley | ||||||
| Oats | ||||||
| Potatoes | ||||||
| Corn for silage | ||||||
| Sugar beet | ||||||
The use of fertilizers slightly reduces the effect of permanent crops, crop rotation in this case increases the yield by 30,0-34,2% for spring cereals and by 34,2-53,4% for winter cereals, which allows the use of permanent crops on a high fertilized background and after good predecessors.
Corn for silage and potatoes are less sensitive to permanent crops. Corn increases yields from crop rotation by 10%, while fertilizer increases yields by 90%, for potatoes by 30 and 60%, respectively. The effect of increasing the yield of these crops from crop rotation regardless of soil fertilization was less significant than for cereals. Thus, in the experiments of the Moscow Agricultural Academy, the yield of winter rye and oats for 69 years (on average) in the rotation without fertilizers was higher by 93% and 76%, respectively, than in the permanent crops, while for potatoes by 16%. Similar results were obtained at the Rothamsted experimental station in England for winter wheat and in Halle (Germany) for winter rye.
For example, farms near Moscow on floodplain fertile well-heated soils were able to obtain good yields of corn for silage for 25-30 years with permanent seeding. Thus, with good fertilization and high agrotechnics, corn for silage can be grown continuously for 10-15 years without a noticeable decrease in yield.
Sugar beet also showed high sensitivity: on unfertilized background yield increase was 2-2.5 times, on fertilized one – 60-70%.
Fiber flax, leguminous, sunflower for seeds sharply reduce the yield when sown in permanent crops, with prolonged cultivation the crops can completely die.
A number of agricultural practices, such as irrigation and fertilization, reduce the impact of permanent crops. In the forest-steppe zone, sugar beet does not withstand permanent crops, dramatically reducing yields, while in the conditions of irrigated agriculture in Central Asia the reduction of yields is much lower. Similar is the attitude of cotton and rice to repeated sowing.
Vegetable crops, according to the research of the All-Russian Research Institute of Vegetable Farming, also showed different effects on permanent crops. Moreover, this influence remains within the crops of the same family, for example, nightshade: tomato, eggplant, pepper; cabbage: cabbage, radish (Raphanus sativus var. radicula), turnip, radish (Raphanus sativus L.), regardless of the sequence of rotation.
Table. Influence of permanent and repeated sowing on the yield of vegetable crops, t/ha[2]Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. - M.: Publishing house "Kolos", 2000. - 551 p.
| 1 year (crop rotation) | |||||||
| 2 years (repeat seeding) | |||||||
| 3 years (repeat seeding) | |||||||
| 4 years (permanent seeding) | |||||||
In general, all crops respond differently to permanent crops. This effect may vary depending on soil and climatic, agrotechnical and other conditions.
All crops can be divided into groups according to their relation to permanent crops.
The first group of crops that do not withstand repeated and even more so the permanent crops. These include sunflower (return to the same place not earlier than 8 years), sugar beet (not earlier than 3-4 years), flax (not earlier than 5-6 years), peas, beans, vetch, clover. Vegetable crops: tomato, eggplant, pepper, cabbage, cucumber. Periodicity of return to the same field for most crops of the group is usually not less than 3-4 years.
The second group of crops that are resistant to repeated sowing without a noticeable decrease in yields. They include barley, oats, winter and spring wheat, winter rye, millet, potatoes, buckwheat, carrots, green vegetables. Resistance of crops of this group strongly depends on the conditions of cultivation. For example, in conditions of the Non-Black Soil Zone, repeated sowing of winter wheat is undesirable, while in steppe areas of the Northern Caucasus and South-East – acceptable, or repeated sowing of spring wheat is undesirable in European Russia, but acceptable in steppe areas of Trans-Ural, Volga, Western Siberia, Altai after bare fallow.
The third group of crops weakly responsive to crop rotation and resistant to permanent crops. They include rice, corn, hemp, tobacco, and cotton. Despite the self-compatibility of crops in this group, it is recommended to alternate them periodically with leguminous, cereals, and other crops. The periodicity of intercropping corn and hemp is 4-6 years or more. Rice, cotton and tobacco, it is also desirable to change periodically with alfalfa, sugar beets, legumes, cereals, etc.
Such a division of crops is rather arbitrary, but it allows one to use it when developing crop rotations, taking into account the principle of compatibility and incompatibility of crops and the principle of periodicity of returning crops to the same field.
The use of varieties resistant to characteristic diseases and pests is a separate method of increasing the resistance of crops to repeated sowing. Chemical and biological preparations can have a similar effect. For example, the use of fusarium-resistant varieties of fiber flax, clubroot-resistant varieties of cabbage, and orobanche-resistant varieties of sunflower can reduce the period of returning to their previous location or cultivating them repeatedly. Application of nematicides – preparations to control beet nematode – allows the use of repeated sowing of sugar beet.
Chemical reasons for crop rotation
The chemical reasons for crop rotation are related to the differences in crop needs for chemical nutrients and the ability to assimilate their hard-to-reach forms.
No single crop is able to increase the accumulation of ash elements in the soil (all except nitrogen), however, crop rotation allows a more rational use of their soil reserves and increase the efficiency of fertilizers.
Thus, crops with deep-rooted system use moisture and nutrient reserves from subsoil layers, and their root residues enrich these layers with organic matter and mineral elements. Deeply penetrating root systems (up to 3 meters and more) have alfalfa, clover, lupine, gourds. At the same time, flax, buckwheat, millet, annual grasses, rape, cucumber, and onion have shallow root systems.
Chemical reasons of alternation are related to the balance of nutrients within the plant. Part of the nutrients is alienated with the harvest and fodder, the other – in the form of plant remains returns back with straw, manure, etc. These features are taken into account when building a crop rotation.
Crops affect the balance of soil organic matter to varying degrees. By leaving plant and root residues after harvest, soil reserves are replenished. However, crops differ in the amount of residues left behind.
In terms of the amount of crop residues left in the soil, plants are arranged in the following sequence in descending order:
- Non-chernozem zone of Russia: perennial grasses – corn for silage – winter cereals – spring cereals – grain legumes – potatoes;
- Forest-steppe zone of Russia: perennial grasses – winter wheat – corn for grain and silage – spring cereals – sunflower – grain legumes – sugar beet.
By changing the structure of cultivated areas it is possible to simulate the balance of organic matter. For example, increasing the share of perennial grasses in the cropping pattern leads to an accumulation of organic matter with a slowing down of its decomposition while reducing the content of available nutrients in the soil.
On the contrary, the increase in the structure of cultivated areas of row crops and bare fallow under conditions of insufficient organic fertilizers leads to a decrease in the reserves of organic matter in the soil.
Introduction of intermediate and green manure crops, such as seradella, sweet clover, lupine, into crop rotation allows to additionally increase the supply of crop residues. In the southern regions under irrigated conditions they leave up to 10 t/ha of residues in one rotation of crop rotation, in the southwestern and central part of the Non-Chernozem region – 3-5 t/ha.
In addition to the accumulation of organic matter, plant residues leave 21.5-51.5% of nitrogen, 1.7-48.1% of potassium, 18.5-51.7% of phosphorus of their total amount in the crop.
Nitrogen
Permanent crops of some crops that consume large amounts of soil nitrogen, such as sugar beets, corn for silage, cabbage, cotton can lead to nitrogen depletion of the soil.
Other crops that promote nitrogen fixation processes by nodule bacteria, primarily legumes (peas, vetch, alfalfa, clover, lupine, seradella, chinna, sainfoin, chickpeas, vigna), on the contrary, are able to accumulate nitrogen annually. For example, annual legumes (peas and vetch) under favorable conditions accumulate up to 50-70 kg of nitrogen per 1 ha; perennial leguminous grasses (clover, alfalfa, sainfoin) accumulate up to 120-150 kg of nitrogen per 1 ha, which is equivalent to the application of 400 kg of ammonium nitrate.
However, repeated and permanent sowing of legumes leads to leaching of accumulated and unused nitrogen from soil to groundwater, as well as to the accumulation of phytotoxic substances, i.e. soil fatigue, resulting in a sharp decrease in yields.
Therefore, alternating legume crops with nitrogen-absorbing crops such as cereals or row crops eliminates the negative effects of permanent cultivation, which ensures the rational use of accumulated nitrogen.
Phosphorus
Potatoes, legumes and winter cereals are distinguished by high phosphorus removal with the harvest.
Crops exhibit different ability to assimilate hard-to-reach forms of soil phosphorus and fertilizers. The greatest ability to absorb hard-to-reach forms is noted in lupine, oats, buckwheat, potatoes, mustard, sugar beets, Hungarian sainfoin, which due to root excretions convert hard-soluble phosphates of soil and phosphate meal into soluble forms.
The alternation of these crops allows a more efficient use of soil phosphorus reserves.
Potassium
The greatest need for potassium is observed in sugar beets – up to 200 kg K2O at a yield of 30 t/ha, potatoes – up to 300 kg K2O at a yield of 30 t/ha, grain crops – up to 50-60 kg K2O at a yield of 3 t/ha, as well as forage root crops, cotton and vegetable crops.
Other nutrients
Physical reasons for crop rotation
Physical reasons of crop rotation are caused by the influence of crops on the texture, density, structure, water regime of soils and resistance to erosion processes. The causes of such influence are biological and morphological properties of crops, primarily the mass, distribution of roots and decomposition of plant residues, as well as the peculiarities of agrotechnics of cultivation.
The dense above-ground part, first of all, of continuous crops (legumes and cereal perennial grasses) contributes to soil protection from erosion, improvement of water and thermal soil regimes, and the organic matter formed from the decomposition of plant residues affects the agrophysical indicators of soil fertility.
Influence on the structure
In terms of the ability of crops to structure, they can be lined up in descending order: perennial grasses – annual legume-grass mixtures – winter cereals – corn – spring cereals – fibre flax – potatoes – root crops.
Perennial grasses
Perennial grasses are able to accumulate a mass of plant residues equal to the mass of the harvested crop. Their root system, penetrating to a great depth, thanks to numerous branching roots, penetrates and divides the soil into individual clumps. After the root residues die off, the clumps are enriched with organic matter, thus creating a water-resistant structure.
Deep penetration and root mass of perennial grasses affects the soil layers below the tilled layer. Clover on sod-podzolic soils enriches the underlying layers with humus and contributes to deeper cultivation of the layer. Alfalfa on saline soils loosens the dense subsoil layer with its roots, creating favorable conditions for subsequent crops.
Cereal crops
Winter cereal crops have the greatest effect of physical change of soils. Unlike spring crops with a shorter growing season, they develop a powerful root system, which in the fall and spring binds the soil and protects it with green cover from destruction by precipitation and melt water.
Tilled (row) crops and bare fallow
Small amounts of crop residues, crops with wide rows and intensive tillage in row crops in most cases contribute to the destruction of soil structure and do not provide sufficient protection against erosion, especially in repeated and permanent cultivation.
Bare fallow has an even greater negative impact on soil structure.
As the long experience of the Moscow Agricultural Academy named after K.A. Timiryazev, the negative effect of bare fallow and row crops on the structure can be reduced by the use of fertilizers, primarily organic ones.
Table. Weight of structural aggregates with a diameter of more than 0.25 mm in the arable soil layer under the permanent crops and bare fallow, % (according to Dospekhov)[3]Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. - M.: Publishing house "Kolos", 2000. - 551 p.
| Clover | |||
| Winter rye | |||
| Oats | |||
| Potatoes | |||
| Bare fallow |
Influence on the water regime of soils
Crops consume soil moisture to varying degrees. The indicator of consumption is the transpiration coefficient.
Technical crops (sunflower and sugar beet) and perennial grasses (alfalfa and Hungarian sainfoin) have the highest water consumption, which dries up the soil to a great depth, which can affect the yield of subsequent crops. Winter crops require more moisture than spring crops. Millet and sorghum consume the least water: for formation of 100 kg of dry matter millet spends 30 t of water, oats and barley – 45-50 t.
The period between harvesting of the preceding crop and sowing of the following one influences the water supply in the crop rotation. During this period, moisture is accumulated due to precipitation and melt water, which is especially important in arid regions.
Alternation of crops in the rotation with different water consumption and depth of root penetration allows to regulate water reserves in the soil.
Root penetration depth for crops:
- flax – 0.8-1 m;
- potatoes – 0,8-1 m;
- winter wheat and rye – 1,5-1,6 m;
- corn and castor beans – 2-2,5 m;
- sugar beet and sunflower – 3-3,5 m;
- alfalfa – 4-5 m.
The greatest effect of moisture accumulation is achieved by using bare fallows, which guarantees high yields of winter and spring wheat in arid areas of the steppe zone.
Biological reasons for crop rotation
Biological reasons for crop rotation are due to different attitudes to diseases, pests and weeds. This is due to the fact that each crop is characterized by its own pests, diseases and weeds. Permanent or repeated crops contribute to the exponential accumulation of characteristic disease-causing organisms, which can lead to the complete death of crops.
D.N. Pryanishnikov gave numerous examples of attempts of permanent cultivation of a number of crops, which ended unsuccessfully first of all because of accumulation of pests and diseases:
- for cotton – Mexican weevil and wilt disease;
- sugar beet – nematodes and beet weevil;
- sunflower – blight and diseases of white and gray rot, etc;
- flax – fusarium, flax weevil and extremely low competitiveness to the majority of weeds;
- clover – clover weevil, anthracnose, cancer, fusarium;
- cereal crops – root rot, Swedish fly, spittlebug, mass infestation of winter crops with broom (Apera), brome (Bromus), cornflower (Centaurea), chamomile (Matricaria);
- spring crops – infestations of wild oat (Avena fatua), barnyard grass (Echinochloa crus-galli), etc.
Specificity of these pests to particular crops makes even modern methods of pest control ineffective. That puts crop rotation in the first place.
At the same time specificity of pests makes them relatively harmless to other crops, due to which crop rotation allows to control prevalence and harmfulness of the majority of them.
Accumulation of pathogens
Accumulation of pathogens (fungi, bacteria, viruses) occurs in the soil and on plant residues. For example, flax, if it is cultivated continuously, dies because of the accumulation of the fungus that causes fusariosis. Sunflower when returned to its original place earlier than 7-8 years is affected by powdery mildew, so crop rotations with a short rotation are not suitable for its cultivation. Cultivation of corn without rotation contributes to accumulation of Fusarium and bladder blight pathogens, of winter wheat – the causative agents of brown rust and dusty mildew, and of cotton – the causative agents of wilt.
The causative agents of root rot of barley and wheat are harmless for oat crops, which is why oats are recognized as a “sanitary” crop in crop rotations. Winter rye can be greatly affected by ergot, but this disease does not harm other crops. Cabbage blight only affects plants in the cabbage family, but does not affect nightshades, umbrellas, or other families.
The main source of conservation and spreading of diseases, primarily fungal ones, is plant residues of host plants. Therefore, soil liberation from pathogens is associated with the rate of residue decomposition.
The main role in the decomposition of plant residues is played by saprophytic microorganisms, which are competitors for life factors with pathogenic fungi. Therefore, all techniques aimed at increasing the activity of soil saprophytes contribute to reducing the number of pathogens, i.e. improve the phytosanitary state of the soil. This is achieved by applying manure, application of green manure and mineral fertilizers, cultivation of legumes, loosening the soil and other methods.
Cultivation of row crops and fallowing, observance of periodicity of returning crops to the same place and refusal of repeated sowing contribute to the reduction of soil pathogens.
Flax is one of the most susceptible crops to diseases caused by pathogenic fungi, primarily fusarium. According to the All-Russian Flax Research Institute, fusarium pathogens can persist in the soil for 5-6 years, which determines the periodicity of flax returning to its previous location. The use of Fusarium-resistant varieties makes it possible to reduce the frequency of return.
Cultivation of potatoes in crop rotation reduces by 4-5 times the incidence of scab and verticillosis diseases.
Not adhering to the recommended timing of sunflower return, according to the All-Russian Research Institute of Oilseeds, increases the infestation of sclerotinia, powdery mildew, and dry rot, which reduce yields by 30-40%.
One common disease among vegetable crops that develops with repeated crops is clubroot in cabbage. Clubroot-resistant varieties have been developed that allow repeated sowing for cabbage, along with its alternation with crops of other families.
Soil fatigue
Soil fatigue is the accumulation of root excretions in the soil that suppress plant growth. Soil fatigue is also associated with the accumulation of characteristic pathogens and their products.
Weeds
Weeds, due to their property of quickly adapting to growing conditions, have become specific to certain crops. Therefore, no-till and repeated sowing leads to the accumulation of specific weeds.
For example, wild oat (Avena fatua) is a specific weed of early spring cereal crops, primarily oats. Boll (Agrostemma), larkspur (Delphinium), shepherd’s purse (Capsella), stinkweed (Thlaspi arvense), bachelor’s button (Centaurea cyanus) grow mainly in winter rye and winter wheat crops; Amaranthus, barnyard grass (Echinochloa crus-galli), mugwort (Setaria pumila), green foxtail (Setaria viridis) – in crops of rice, millet and corn.
The permanent crops of winter crops increase the number of winter and wintering weeds, the late spring crops – late spring weeds, the fields of perennial grasses – perennial, biennial, wintering and winter weeds.
Cultivated plants exhibit various competitive abilities in relation to weeds. Sowings of summer grasses, winter rye, and winter wheat show high competitiveness. Flax, sugar beet and spring wheat crops are characterized by weak competitiveness. Barley and corn crops are characterized by medium competitiveness. Some crops may exhibit high competitiveness to some weeds and low competitiveness to others.
Crops of row crops and bare and seeded fallow crops have the most favorable conditions for weed control, thanks to frequent weeding and tillage. Correct alternation with crops of continuous crops, allows to keep under control the weed infestation of fields. Increasing the proportion of continuous crops in the cropping pattern increases the weediness of fields, while increasing the proportion of row crops and fallows decreases it.
Sunflower, corn, castor bean, and hemp are capable of natural weed suppression due to wide leaves and stem height. Winter wheat and winter rye also have this ability due to rapid growth in the spring, outrunning many weeds.
Table. Weediness of winter wheat crops depending on crop rotation and fertilizers[4] Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. - M.: Publishing house "Kolos", 2000. - 551 p.
| Early potatoes | ||||
| Clover | ||||
| Corn for green fodder | ||||
| Peas | ||||
| Permanent seeding (3-4 years) | ||||
According to S.A. Vorobyov’s research, the weed infestation in the winter wheat crops in the conditions of the Moscow region was 4-5 times higher than after the predecessors.
Crop rotation makes it possible to maximize the competitive advantage to control specialized weeds of other crops. For example, spring crops crops suppress weeds characteristic of winter crops, primarily winter and biennial plants. On the contrary, crops of perennial grasses and winter crops sharply suppress early and late spring weeds.
Pests
Similarly to pathogens and weeds, favorable living conditions and distribution of pests characteristic of the crop are created in repeated and permanent crops. Thus, the reproduction of nematodes and beet weevil in repeated crops of sugar beet increases, while in millet crops – the millet weevil. Irregular crop rotation and shortening of the period of return to the previous location in spring and winter wheat crops result in accumulation of beetles, grain sawfly, Swedish and Hessian flies, lapwing beetle, and cougar beetle. Crop rotation, along with the use of pesticides, can significantly reduce the population of many pests and reduce the damage caused by them.
In cases of resistance of some pests to control means or low efficiency of pesticides, crop rotation becomes of primary importance in the struggle, especially against nematodes.
According to the data of Bashkir State Agrarian University, the area of nematode infestation of permanent crops of winter rye has increased to 66% and that of spring wheat to 91.3%. Reduction of yield during repeated sowing of sugar beet on the fields heavily infested with nematode was 60-70%.A similar situation was observed in repeated sowing of potatoes or their frequent return of potato nematode.
In addition to the cultivation of crops in the same location contributing to the accumulation of crop-specific pests, the effect of preceding crops on subsequent crops should also be considered. For example, crops of perennial grasses contribute to the spread of the wireworm, which strongly damages subsequent crops, such as cereals, corn, and potatoes. According to S.A. Vorobyov, in the fields of the Mikhailovskoe farm of the Timiryazev Moscow Agricultural Academy near Moscow, the number of wireworm larvae in winter wheat cultivated after corn for silage was 13 larvae per 1 m2, while 88 larvae were found after clover in the 2nd year of use.
Economic reasons for crop rotation
Economic reasons for crop rotation are conditioned by the structure of sown areas, natural and economic factors of agricultural production in order to ensure maximum profitability under the condition of stable farming.
The structure of sown areas are developed under the conditions of a particular enterprise on the basis of production plans, taking into account the productivity and economic efficiency of crops and the impact on soil fertility. Different plants in different soil and climatic conditions may give different amounts of fodder units of different quality, which is associated with their biological characteristics. For example, sugar beet or corn, in one zone can give a high yield per unit area and therefore be economically profitable, in another zone, on the contrary, give a low yield and be unprofitable.
In economic terms, crop rotation should ensure:
- maximum rational and productive use of land with simple or extended reproduction of fertility;
- demand of an enterprise (if necessary) for fodder and seeds;
- uniform use of machinery;
- the implementation of modern intensive technologies;
- effective labor organization.
As D.N. Pryanishnikov noted, economic necessity of crop rotation is connected with different quantity and distribution of labor in time necessary for cultivation of different crops in a farm.
Thus, cultivation of early and late spring crops due to different terms of sowing and harvesting allows reducing the load on people and machinery in the same period by 2 times than when cultivating only early or only late spring crops. The addition of winter crops allows even more even distribution of the intensity of field work.
The use of varieties of different maturity dates has a similar effect.
In this case, the risk of non-compliance with the optimal timing of field work is reduced.
A certain ratio of cereals, industrial and forage crops allows to build a balance of manure-forming (forage) and manure-consuming (grain, row crops) plants.
Economic reasons are related to other reasons for crop rotation, as proper crop rotation, contributes to higher economic returns of production. For example, with the help of crop rotation in combination with a number of agricultural practices it is possible to reduce the weed infestation of crops, reduce the population of pathogens and pests to the economic threshold of harmfulness, thereby reducing the cost of agrochemicals and increasing yields, which increases the profitability of production.
Ecological reasons for crop rotation
The ecological reasons for crop rotation are due to the replacement or reduction of agrochemical use through the positive impact of properly constructed crop rotations on the weed infestation of fields and populations of harmful organisms. Moreover, crop rotation plays an important role in the system of conservation agriculture.
Thanks to the use of agrotechnical and biological methods of controlling weeds and pests, the oversaturation of land with pesticides is prevented, which contributes to pollution of soils and groundwater by residual amounts of agrochemicals.
Agro-ameliorative measures aimed at protecting the soil and the environment include:
- creation of buffer strips along field boundaries;
- planting of protective forest plantations;
- creation of a network of roads on fields;
- organization of moisture retention systems for precipitation and melt water;
- construction of irrigation systems, etc.
In addition to ameliorative measures, soil protective measures include special agrotechnical methods of contour tillage and shelterbelt and kuli placement of crops.
This provision is regulated by the Federal Law of the Russian Federation “On Environmental Protection”, aimed at reducing the ecological threat associated with agricultural activities. Thus, crop rotation is an integral part of ecological land use within the boundaries of single agro-landscapes.
Prevention of water erosion of agricultural lands that are part of agrolandscape (meadows, pastures, forests) is achieved by using special contour tillage methods (plow subsurface, mole cutting, ridging). Prevention of wind erosion, for example, in steppe areas, the shelf placement of crops of crop rotation and bare fallows across the prevailing winds is used, combining them with the coulisses in the system of non-moldboard-and-ploughshare tillage. Thus, the system of crop rotations, as well as a single crop rotation, perform a soil-protecting function.
The ecological function of crop rotations is manifested in their ability to reduce the content of harmful substances, pesticides and growth regulators accumulated from industrial agricultural activities, reducing the risk of their penetration with runoff water into rivers, reservoirs and groundwater.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.
Crop rotation
Crop rotation is the alternation of crops and bare fallow on the occupied fields (plots) for a certain period, ranging from 2-3 years to 12 years or more, based on the accumulated agricultural science experience and knowledge.
Crop rotation is the basis of farming
Modern agriculture is an interrelated complex of technological, organizational and economic tasks, the solution of which is the leading task of agronomists and managers of agricultural enterprises. The solution of these problems is based on the experience and knowledge of biology and technology of growing crops, organizational, environmental, soil-climatic, economic and other aspects of production.
Crop rotation is a system solution of one of the tasks of production activity: rational use of lands with the account of their possible effective fertility, biological potential of plants and available resources (heat, climate, fertilizers, agricultural machinery and agrochemicals) for the purpose of the most profitable management, which is possible with high crop yields, with simultaneous reproduction of fertility and environmental protection.
As a consequence, crop rotation is the basis of modern zonal agro-landscape farming systems. It determines the majority of other systems: tillage and protection from erosion processes, fertilization, plant protection, seed and varietal change, irrigation and drainage, machinery, labor organization, etc.
The basis of the organizational structure of large agricultural enterprises is a system of basic, more often field crop rotations, assigned to certain units (farms) of the enterprise, which provide a full cycle of work on the maintenance of this crop rotation.
The task of crop rotation includes uninterrupted provision of livestock complex with fodder of required quality, quantity and energy value, determined by the fodder balance.
The essence of crop rotation
Modern agriculture is a multi-sectoral production, combining, as a rule, livestock and crop production. Depending on soil and climatic, economic and other conditions, as well as the specialization and scale of production in each farm there is a certain structure of sown areas.
The structure of cultivated land – the ratio of areas under crops and bare fallow.
Planning the structure of areas allows the most efficient use of land resources, taking into account the natural, economic and agronomic conditions.
The size of the fields is determined by the cropping pattern, the topography and natural boundaries, and the type of crop rotation. For example, crop rotations with a short rotation allow for larger fields, whereas in multifield crop rotations a long rotation is used. In the steppe and forest-steppe zones, more often, fields are larger than in the forest-meadow zone. It is desirable that the fields in the rotation have approximately equal areas.
Example. On one arable land it is necessary to sow 4 cultures with the following structure of the sown areas: winter wheat – 25%, potatoes – 25%, barley – 25%, mixed crops for green fodder – 25%. For this purpose, the arable area is divided into 4 equal fields, on which one crop is placed. In subsequent years, there may be two ways of placing these crops on the fields.
In the first case, each crop is placed in the same field where it already grew, and thus they will be referred to as a permanent crop.
A permanent crop is a crop that is cultivated for a long time in the same field.
A monoculture is the only perennial crop grown on a farm. Often the term “monoculture” is used as a synonym for “permanent crop”.
Centuries of accumulated farming experience shows: the permanent cultivation of almost all agricultural plants leads to a significant reduction in yields, and in some cases to the death of the crops.
The second option of crop placement from the example assumes their annual replacement on four fields in a predetermined sequence, i.e. in the order of alternation by years.
The most effective and scientifically grounded sequence of alternation for the listed crops is as follows: 1 – forage vicia-oat mixture, 2 – winter wheat, 3 – potatoes, 4 – barley. In this case, each crop is the predecessor of the one that comes next year.
The predecessor is a crop or fallow that occupied the field before the subsequent crop in the rotation.
The given scheme of alternation assumes the following placement by fields and years:
| Field No. 1 | Field No. 2 | Field No. 3 | Field No. 4 | |
| 1 year | Winter wheat | Barley | Potatoes | Vicia-oat mixture |
| 2 year | Potatoes | Vicia-oat mixture | Barley | Winter wheat |
| 3 year | Barley | Winter wheat | Vicia-oat mixture | Potatoes |
| 4 year | Vicia-oat mixture | Potatoes | Winter wheat | Barley |
Regardless of the crop that occupies the field in the first year, within 4 years each of them will pass through each field and the rotation of the crop rotation will be completed.
Rotation is the period during which all crops and pairs will pass through each field in the sequence provided by the crop rotation. The rotation chart above is called a rotation table.
The rotation duration in the example is 4 years. The rotation is determined by a rotation schedule with a duration equal to the number of fields. The number of fields in the rotation is determined by the number of crops and their ratio, taking into account the location of land, topography, soil differences and other conditions.
Traditionally, it is customary in crop rotation schemes to designate rotation numbers with Arabic numerals and field numbers with Roman numerals. When a crop rotation is introduced, each field is assigned a permanent number, which is retained in the crop rotation and land management documents, on boundary marks located along the borders of the fields, as long as the crop rotation scheme is used.
After the completion of the first rotation, the subsequent rotation begins with the placement of crops on the same fields on which they were placed in the first rotation. However, during the course of a crop rotation, for many reasons, crop rotation schemes may be altered.
A rotation scheme may include both individual crops and groups of crops, usually with similar properties: cereals (winter or spring), leguminous, row crops, perennial grasses, annual grasses, bare and seeded fallow. For example, the rotation scheme would look as follows: 1 – annual grasses, 2 – winter cereals, 3 – row crops, 4 – spring cereals. This approach allows you to adjust the crop rotation, if necessary, without changing it as a whole. For example, in the above example, crops can be replaced by: 1 – pea-barley mixture green for fodder, 2 – winter rye, 3 – corn for silage, 4 – oats, while keeping the rotation and structure of areas.
As a rule, one crop occupies one field. However, in certain crop rotations, often with a short rotation, it is possible to sow several similar crops in the same field. For example, a field of winter cereals may contain winter rye and winter wheat, a field of row crops may contain potatoes, corn for silage and forage root crops, a field of spring cereals may contain oats and barley, etc. In this case the field will be a combined field.
Prefabricated crop rotation field is a field on which several crops are cultivated.
Repeated crops – crops cultivated on the same field 2-3 or more years in a row with its subsequent replacement until the rotation of the rotation is completed. In some cases, such as perennial forage grasses – legumes, cereals, or their mixtures, which occupy several years one field does not qualify as repeated crops, as the cycle of their development in each year differs from the previous by the composition of the herbage and its use.
Sod-liking crop is a crop that comes after perennial grasses in the rotation. Post-sod-liking crop is a crop that follows the rotational crop after the sod-liking crop.
Scientific basis of crop rotations
Main article: Arable farming: Scientific basis of crop rotations
Scientific basis of crop rotations – a number of reasons for the need to rotate crops.
All crops react negatively to repeated sowing and growing in the same place. For some crops it is manifested by a slight decrease in yields, for example, potatoes and corn, for others – a sharp decline and death of crops, for example, fiber flax, sugar beets, sunflowers.
The reasons for the need to alternate crops were first summarized by D.N. Pryanishnikov. He singled out four reasons:
- physical;
- chemical;
- biological;
- economic.
The physical reasons for the need to alternate crops are due to their influence on the texture, density, structure, water regime of soils and resistance to erosion processes. Some crops, such as perennial grasses, due to the large amount of plant residues, replenish the balance of organic matter, thereby significantly improving its agrophysical indicators of fertility. Others, on the contrary, have a negative impact, such as row crops and bare fallow, the cultivation of which significantly depletes humus in the absence of organic fertilizers, thereby worsening the indicators of soil fertility. Appropriate tillage allows the creation of optimal soil regimes for plant life, which are the physical causes of crop rotations.
Chemical reasons of crop rotations are caused by disproportion in the balance of mineral nutrients, when crops are cultivated continuously. For example, leguminous crops accumulate nitrogen in the soil, which is lost by the soil under permanent crops, the placement of leguminous crops in the following year grain crops allows to use the accumulated nitrogen for the formation of the crop.
Chemical reasons include the balance of organic matter, which is an integral indicator of soil fertility. Different groups of crops have different effects on the amount of organic matter in the soil. Some, such as perennial grasses leave a large amount, positively affecting subsequent crops, others, such as row crops deplete the stock of humus.
Biological reasons for crop rotation are explained by the accumulation of pests, disease-causing agents and characteristic weeds in repeated and permanent crops, which generally has a strong effect on yields. In addition, plants are also affected by the phytoactive substances accumulated in the soil of the same crop, which leads to the manifestation of the effect of soil fatigue.
The combination of these reasons explains the decrease in crop yields when crops are repeatedly sown and permanently grown in the same place.
Economic reasons of crop rotation are caused by organizational and technological factors of production.
Thus, crop rotation allows to regulate the listed factors, optimizing them for production needs.
Classification of crop rotations
Main article: Arable farming: Classification of crop rotations
The modern classification of crop rotations divides them into types and kinds.
The type of crop rotation determines the production purpose of the crop rotation:
Type of crop rotation determines the structure of sown areas and the order of alternation of crops in it:
- cereal-fallow;
- cereal-fallow-grass;
- cereal-fallow-row;
- cereal-grass;
- cereal-row;
- cereal-grass-fallow-row;
- cereal-grass-row; (fruit-changing);
- grass-row;
- row crop;
- grass fields;
- sideral;
- grass-cereal;
- fallow-row.
Separately crop rotation may be classified by specialization, that is, by the dominant crop in the structure of cultivated areas: beet, grain, potato, flax, etc.
Depending on the form of agricultural production, for example, in the conditions of small farms, specific crop rotations are distinguished, for example, crop rotations in farms.
Creating a crop rotation
Main article: Arable farming: Creating a crop rotation
The creation of crop rotations is based on the grouping of crops according to common biological characteristics and methods of tillage in their cultivation and on the general principles of building crop rotations.
Crop rotation groups:
- bare fallows,
- seeded fallows,
- perennial grasses,
- leguminous crops,
- row crops,
- technical non-row crops,
- cereal crops (winter and spring),
- intermediate crops.
Principles of crop rotations creation:
- principle of adaptability;
- principle of biological and economic expediency;
- principle of changeability;
- principle of periodicity;
- principle of compatibility and self-compatibility;
- principle of compacted use of arable land;
- the principle of specialization.
Due to such systematic it is possible to build any type of crop rotation that meets the objectives of agricultural production, adapted to local soil and climate, organizational and production and market conditions.
Design, maintenance and development of crop rotations
Main article: Arable farming: Design, maintenance and development of crop rotations
In the conditions of large agricultural enterprises the need for large-scale development of arable land is possible, requiring the consideration of a large number of factors and long-term planning of economic and production activities, consistent with the requirements of the land management legislation.
For these purposes a comprehensive approach to building a system of crop rotations is necessary. For this purpose, the design of a system of crop rotations, their introduction and development is carried out.
The system of crop rotations allows to provide the necessary needs as individual production objects of agroenterprise, and as a whole, allows to build the most effective system of sustainable agricultural production.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.
Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.
Useful properties of weeds
Habitat indicators
Many weed species are confined to certain field communities and soil habitat conditions. In the latter case, the response of weeds can be considered as an indication of natural edaphic conditions and as a response to soil properties, including those changed by agrotechnical measures.
The response of weeds to edaphic conditions is primarily manifested in responsiveness to moisture supply, reaction of soil environment and nutrient supply.
Plants-indicators of soil water regime
In relation to the level of soil moisture there are groups of weeds:
- hygrophytes – occur exclusively in damp, poorly aerated soils: marsh swift-leaf (Gnaphalium uliginosum), frogweed (Juncus bufonius), field broom (Apera spica-venti), field horsetail (Equisetum arvense), field mint (Mentha arvensis), marsh hedgenettle (Stachys palustris), creeping buttercup (Ranunculus repens);
- hygromesophytes – prefer damp well aerated soils: lamb’s-quarters (Chenopodium album), Chenopodium polyspermum, Fumaria officinalis, cleavers (Galium aparine), Tripleurospermum inodorum, stinkweed (Thlaspi arvense), perennial sow thistle (Sonchus arvensis);
- xerophytes – prefer well aerated, warm, sometimes strongly drying, soils: redroot pigweed (Amaranthus retroflexus), prostrate pigweed (Amaranthus blitoides), Stachys annua, storksbill (Erodium cicutarium), smolt-cracker (Silene vulgaris), green foxtail (Setaria viridis), barnyard grass (Echinochloa crus-galli), Common ragweed (Ambrosia artemisiifolia).
Plants-indicators of soil acidity
According to the reaction to the pH value of the soil solution (actual acidity), there are groups of plants-indicators of soil acidity:
- oxylophytes – grow mainly on soils with a pH value < 5.0: small sorrel (Rumex acetosella), corn spurrey (Spergula arvensis), knawel (Scleranthus annuus), toricum of the field (Arenaria arvensis), chamomile non-scented (Tripleurospermum inodorum), wild radish (Raphanus raphanistrum), field broom (Apera spica-venti), frogweed (Juncus bufonius);
- oxymesophytes – grow on soils with soil solution reaction from slightly acidic to neutral: wild oat (Avena fatua), sprawling swan (Atriplex patula), wormseed mustard (Erysimum cheiranthoides), stinkweed (Thlaspi arvense), Black henbane (Hyoscyamus niger), marsh hedgenettle (Stachys palustris), Potentilla anserina, perennial sow thistle (Sonchus arvensis);
- plants indifferent to the reaction of soil solution: lamb’s-quarters (Chenopodium album), shepherd’s purse (Capsella bursa-pastoris), purple cockle (Agrostemma githago), horseweed (Erigeron canadensis), Galeopsis speciosa, Achillea yarrow.
The presence of several species of weeds of the same group gives grounds for assessing the advisability of liming soils. This method often leads to a change in the floristic composition of weeds and reduces the weed infestation of crops.
Plants-indicators of nutritional regime
According to the level of responsiveness to the supply of soil elements of mineral nutrition (nutritional regime), there are “element-positive” and “element-negative” groups of weeds. In the practice of farming it is important to know the indicator plants that respond positively to high content of certain elements of mineral nutrition in the soil.
The group of nitrophiles (nitrogen-loving) includes lamb’s-quarters (Chenopodium album), multiseed (Chenopodium polyspermum), sprawling swan (Atriplex patula), wild radish (Raphanus raphanistrum), wild mustard (Sinapis arvensis), rugged mountain knotweed (Persicaria lapathifolia), conspicuous bunting (Galeopsis speciosa), double-cut bunting (Galeopsis bifida), barnyard grass (Echinochloa crus-galli), annual bluegrass (Poa annua), small sorrel (Rumex acetosella).
Phosphatophiles include the following species: groundsel (Senecio vulgaris), field violet (Viola arvensis), corn spurrey (Spergula arvensis), red broom (Spergularia rubra), apothecary woodruff (Fumaria officinalis), henbit (Lamium amplexicaule).
Potassiumophiles include cleavers (Galium aparine), spreading lambsquarter (Atriplex patula), stinkweed (Thlaspi arvense), perennial sow thistle (Sonchus arvensis).
The above classification of weeds in relation to the various elements of mineral nutrition is not absolute, because with a change in mineral nutrition other conditions of life change. Therefore, the response of weeds to individual elements may also change.
Sources
Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.