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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.

Fields of crop rotation
Fields of crop rotation

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. 1Field No. 2Field No. 3Field No. 4
1 yearWinter wheatBarleyPotatoesVicia-oat mixture
2 yearPotatoesVicia-oat mixtureBarleyWinter wheat
3 yearBarleyWinter wheatVicia-oat mixturePotatoes
4 yearVicia-oat mixturePotatoesWinter wheatBarley

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), legumes, 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:

  • field;
  • forage;
  • special purpose.

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.