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Row crops of 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)

The predecessor
Yield of spring wheat, t/ha
without fertilizer
with fertilizer
Peas
1.97
2.69
Corn
1.97
2.65
Sugar beet
2.00
2.76
Potatoes
1.89
2.86
Winter rye
1.71
2.37
Spring wheat
1.63
2.38

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.