Minimum tillage

Importance of minimizing tillage

The need for minimum tillage is determined by reducing energy and labor costs for its implementation. In modern crop cultivation technologies, tillage accounts for up to 25% of labor and 40% of energy costs.

Intensification of agriculture requires increasing tractor power and implement working width, but at the same time reducing weight and pressure on the soil. For example, a K-701 tractor with a mass of 12 t exerts pressure through its wheel running systems of 1.7–1.8 kg/cm². The permissible load on soils in a state of physical maturity during plowing is 1.0–1.2 kg/cm². Excessive compaction worsens the agrophysical properties of the soil, reducing, for example, field germination of winter wheat seeds by 25% and yield by 12–30%.

The use of intensive tillage in crop rotations with a predominance of annual plowing activates microbiological processes of humus decomposition. Chernozem soils under moldboard tillage lose 0.8–1.2% humus over 30 years, which negatively affects the organic matter balance and leads to significant losses of nutrients and energy. Accelerated humus decomposition promotes erosion processes, especially on sloping lands. For this reason, minimum tillage is considered a most important condition for preserving potential and increasing effective fertility, protecting soil from erosion by improving the humus balance and reducing nutrient losses. Along with this, it significantly reduces energy costs for tillage and the time required for field work.

The most important conditions for the effective use of minimum tillage are:

• high technological level of crop cultivation;
• high-quality mechanized field work in optimal timeframes;
• provision of the enterprise with effective plant protection products and fertilizers.

Minimization of tillage is achieved by high technical equipment of the enterprise with combined tillage and sowing units that combine up to 4–5 technological operations, for example, tillage, application of fertilizers and herbicides, and sowing.

Minimum tillage is primarily necessary on chernozem, chestnut, gray forest, and well-cultivated sod-podzolic soils with agrophysical properties optimal for plants, in fields free from perennial weeds. For example, reducing the number of deep tillage operations on chernozem, chestnut, gray forest, and other soils is possible when the equilibrium density is approximately equal to the optimal and does not exceed 1.2–1.3 g/cm³ for cereal crops, and the air content is not less than 13–15% of the soil volume.

The suitability of soils for minimum tillage is determined by a number of fertility indicators:

• humus content;
• water-stable structure;
• porosity coefficient;
• degree and type of field weed infestation.

For example, sod-podzolic soils are considered suitable when the humus content is at least 2%, water-stable aggregates, i.e., particles less than 0.25 mm, are more than 25–30%, and the porosity coefficient is more than 0.9. Soils with a porosity coefficient less than 0.9 have an unstable structure and are prone to compaction, which negatively affects yield.

The main directions of minimum tillage include:

• reducing the number and depth of primary, pre-sowing, and inter-row tillage in crop rotations on highly fertile soils with favorable agrophysical properties, provided that herbicides are used (if necessary);
• replacing deep primary tillage for certain crops in crop rotation with surface and shallow tillage through the use of wide-cut flat-cutting, chisel, disk, and other implements, especially for winter and spring cereal crops;
• combining several technological operations and practices in one working process through the use of combined tillage and sowing units;
• using direct sowing of cereals and maize without preliminary or strip (in the row zone) pre-sowing tillage when growing row crops.

The choice of minimum tillage practices depends on the fertility level, moisture conditions of the zone, biological characteristics of the crop, and degree of field weed infestation.

When herbicides are used, the number of inter-row cultivations in row crop stands is reduced. On light soils, one pre-sowing harrowing is carried out for early spring crops, and in the primary tillage system deep plowing is periodically replaced by shallow tillage or disking to 10–12 cm.

When cultivating potato, root crops, and vegetables in fields not infested with perennial weeds, autumn plowing is excluded or replaced by stubble cultivation. This practice is effective on sod-podzolic soils that are light in particle-size composition, dark gray forest soils, and other well-cultivated soils.

Good mixing of soil with fertilizers is achieved during spring pre-planting rotary tillage using tools with active working parts, for example, KFG-3.6, PR-2.7, which improves tillage quality and increases yield by 10–20%.

Minimum tillage is especially effective on chernozem soils of the Central Chernozem zone, North Caucasus, and Volga region when cultivating winter wheat following grain legumes, annual grasses, and maize for silage.

Plowing is replaced by shallow loosening to a depth of 10–12 cm using disk and share stubble cultivators, flat-cutting cultivators of the KPSH-9 and KPSH-11 types, equipped with BIG-3A needle harrows and ring-spur rollers.

Minimization of primary tillage is achieved by combining plowing and additional practices for leveling and soil compaction. For this purpose, combined plowing units are used, for example, PKA-2, including a plow, a rail drag in the form of an angle-iron beam, and sections of ring-spur rollers, which incorporate plant residues and sod well, level and compact the soil. To improve crumbling and leveling of the soil during plowing, 5- and 6-furrow plows are equipped with special attachments of the PVR-2.3 type (narrow wedge and ring disks), and semi-mounted 7- and 9-furrow plows — PVR-3.5.

Combined tillage and sowing units, for example, KA-3.6 (rotary tiller and grain drill), MKPP-3.6 (cultivator and grain drill), PKR-3.6, SZS-2.1M, SZS-6, SZS-12, KFG-3.6, and others, make it possible to combine pre-sowing tillage, fertilizer application, sowing of cereals, and soil rolling.

The use of units with rotary working parts makes it possible to abandon plowing; the quality of pre-sowing tillage improves, labor productivity increases by 1.6–2.2 times, and labor costs decrease by 30–40%. Grain crop yields increase by 0.35–0.39 t/ha.

Flat-cutting tillage protects the soil from erosion and reduces energy costs compared with plowing. In areas of wind erosion, sowing units that combine in one pass pre-sowing tillage, band fertilizer application, sowing, and rolling are more effective. For these purposes, a stubble cultivator-drill LDS-6 and others are also used.

High-quality pre-sowing tillage of plowed soil for sowing cereals, sugar and fodder beet, and maize is provided by the use of combined units, for example, RVK-3.6, RVK-5.4, VIP-5.6. In one pass they crumble clods, level the surface, and compact the soil.

For pre-sowing tillage of chernozems subject to wind erosion, plowing is replaced by the use of combined units of the AKP-2.5, AKP-5 type, including disk and flat-cutting working parts, needle harrows, and a ring-spur roller. They are used to prepare soil for winter crops following non-fallow stubble predecessors.

The use of APL-1.5 and APL-2 units is effective in radical improvement of meadows and pastures; in one pass they apply fertilizers, loosen the soil, shred sod, sow grass seeds, and roll the soil in rows. Combining these operations accelerates the cultivation of meadows and pastures and increases their productivity with lower labor and energy costs.

Annual surface and flat-cutting tillage increase field weed infestation by 25–30%, especially by perennial weeds, and crop damage by diseases and pests. For this reason, moldboard and non-moldboard tillage are alternated in crop rotation with the use of effective plant protection products. Long-term surface and shallow tillage cause sharp differentiation of the arable soil layer, with accumulation of humus and nutrients in the upper 10-cm soil layer.

Reduced biological activity in the lower layers and microbial mobilization of nitrogen in the upper 10-cm layer worsen nitrogen plant nutrition. For this reason, under minimum tillage, rates of nitrogen fertilizers are increased by 10–15%.

Constant surface tillage also leads to compaction of the lower soil layers; their water and air permeability deteriorate, which necessitates periodic deep loosening using non-moldboard or chisel tools.

References

1. Bazdyrev G. I., Loshakov V. G., Puponin A. I., et al. (2000). Agriculture. Textbook for universities. Moscow: Kolos Publishing House.

2. Niklyaev V. S. (2000). Fundamentals of agricultural production technology. Agriculture and crop production. Moscow: Bylina.

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