Soil Tillage System

Principle of Variable-Depth Tillage in Crop Rotation

The principle of variable-depth tillage in crop rotation substantiates the need to alternate deep, shallow, and surface tillage, taking into account the features of the agrolandscape, the biological requirements of crops, and their responsiveness to tillage depth and arable layer thickness. For example, crops with a fibrous root system predominantly located in the upper layers and insufficiently using deep soil layers respond weakly to deep tillage. Therefore, the tillage depth when these crops are placed in grain-grass, fruit-rotation, and other crop rotations, especially on fields weakly infested with perennial weeds, is up to 10–12 cm.

Crops with a taproot, deeply penetrating root system (legumes, fodder, and row crops), by contrast, respond well to deep tillage. They use the subarable layers loosened by deep tillage quite effectively. For this reason, the soil tillage system in crop rotation is built on periodic alternation of variable-depth moldboard, chisel, and other tillage operations. Variable-depth tillage allows good loosening of the “plow sole” and incorporation of seeds and vegetative organs of weed reproduction.

Principle of Minimizing Tillage

The principle of minimizing tillage is applicable primarily on well-cultivated, highly fertile soils with optimal agrophysical properties. Such soils include chernozems, chestnut, dark gray, and well-cultivated sod-podzolic soils. On such soils, the number and depth of loosening can be reduced to a minimum, and herbicides can be used to control weeds. Shallow and surface tillage are effective for winter and spring cereals, as well as intermediate crops. Zero tillage is also classified as minimal.

The main directions of tillage minimization include:

• Reducing the number and depth of main, pre-sowing, and inter-row tillage, replacing deep tillage with surface and shallow tillage using wide-reach implements.
• Combining several technological operations.
• Using herbicides instead of mechanical tillage.
• Mulching the soil with straw or green mass of green manures.
• Sodding low-productivity soils subject to erosion risk.

Better quality of pre-sowing tillage of previously plowed soil is provided by combined units, for example, RVK-3.6, RVK-5.4, VIP-5.6, VPN-5.6, VP-8, and others. When there is no plowing, rotary tillers and rotary cultivators KFG-3.6, KA-3.6, and others are used. The use of combined machines and implements with various working parts in combination with mulching with straw and plant residues expands the possibilities of minimization, reducing the intensity coefficient to 0.46–0.56, which is especially important on erosion-hazardous lands.

Scientific data indicate the high effectiveness of minimization, which allows reducing the number of machine passes across the field, shortening work completion times, increasing labor productivity by 1.5–2 times, and reducing energy costs by 30%. Thus, reducing the depth of main tillage for winter crops from 20 to 10–12 cm reduces diesel fuel consumption by 7–10 l/ha. Minimization of tillage also has negative results: field weed infestation and plant damage by pests and diseases increase. Prolonged surface and shallow tillage lead to differentiation of fertility between the upper and lower layers, accumulation of humus and nutrients only in the upper 10-centimeter cultivated soil layer, and depletion of nitrogen and excessive compaction of the lower uncultivated layer.

Principle of Soil-Protective Expediency and Ecological Adaptability of Tillage Practices and Technologies

The principle of soil-protective expediency and ecological adaptability of tillage practices and technologies is aimed at preventing erosion processes and protecting the soil, reducing the negative impact of erosion on soil and the environment to acceptable levels. The principle is based on ecological assessment and selection of a tillage method with high erosion-control effectiveness.

In steppe agrolandscapes, the tillage system is based on non-moldboard, flat-cut, mulching tillage using loosening but non-inverting working parts such as paraplow, SibIME tines, and flat-cut implements while preserving 70–80% of stubble on the soil surface. Mulching eliminates soil overheating in summer, promotes accumulation and preservation of soil moisture, and prevents erosion.

Intensive annual soil loosening disrupts the dynamic equilibrium in the ecological system soil–plant–atmosphere. Increased aeration activates humus decomposition, destroys soil structure, and increases unproductive losses of nutrients. Thus, unproductive losses of organic carbon during crop formation amount to 40–50%. The use of non-moldboard tillage reduces this indicator to 25–30%, which positively affects the organic matter balance and increases the erosion resistance of the soil.