Effective tillage after harvesting cereal crops in the Kuban region

Following harvesting of small grains">harvesting of small grains predecessors — mainly winter barley and winter rapeseed — there remain 2–2.5 months until the optimal sowing date for winter crops. This period must be used for quality soil preparation. The sooner the field is cleared of straw, the more opportunities arise for applying various tillage techniques. Under normal conditions, the plough layer has no compacted layers, and its porosity rarely falls below 50 %.

However, if the predecessor was sown using minimum tillage, the soil density will be higher. The risk of severe compaction increases if it rains during harvesting. Heavy harvesting machinery and transport roll the moist soil to a depth of 25–30 cm or more, increasing density to 1.35–1.5 g/cm³. On heavy soils in the western and southern foothill zones, the density of the cultivated layer is always higher than in the northern and eastern districts.

• Optimal humidity for crumbling — 22–28 %
• Optimal soil density — up to 1.25 g/cm³
• Available soil moisture reserve in the 0–20 cm layer — from 0 to 58 mm
• Stand density for weed suppression — 350–400 plants/m²
• Minimum stubble discing depth — 6–8 cm

Stubble tillage timing and soil crumbling quality

The main task of half-fallow stubble tillage is to create a fine-crumbly, non-cloddy, and slightly compacted layer with a leveled surface. The main factor for success here is carrying out the work immediately after harvesting. After mowing the crop, exposed soil quickly loses moisture through cracks that form and reach deep underground. Early tillage allows for the preservation of moisture and prevents the appearance of large clods.

If the small grain predecessor was free of weeds due to good tillering and stand density, this facilitates the work. However, regardless of the level of weed infestation, the gap between harvesting and tillage is unacceptable, otherwise, the stubble will quickly become overgrown with weeds. In field work, it is important to adhere to the strict rule: "combine off the field — plough into the furrow." Every day of delay reduces the future yield of winter wheat, as confirmed by field research data:

Choosing ploughing depth and the use of stubble discing

For steppe regions, a ploughing depth for winter wheat exceeding 20–22 cm is not practical. Soil density below this mark naturally remains favorable for the development of the plants' root system. Excessive ploughing depth only harms the crops, especially in conditions of a dry and hot summer. Deep loosening accelerates the drying of the topsoil due to diffuse moisture losses, which prevents uniform emergence.

If it is not possible to carry out ploughing at the optimal time, stubble discing helps to compensate for the delay. This operation reduces the negative effect of late ploughing performed 3–4 weeks before sowing. However, discing will only fulfill its task if carried out to a depth of at least 6–8 cm. At the same time, it should be remembered that even high-quality discing cannot completely eliminate yield losses from late ploughing.

When is it necessary to increase ploughing depth and how to combat re-compaction

The use of shallow flat-cut tillage for winter wheat on ordinary and leached chernozems reduces crop yield. This method does not replace traditional ploughing and leads to a grain shortfall due to the activation of diseases.

The maximum yield of winter wheat after a small grain predecessor is obtained with ploughing to a depth of 20–22 cm, sowing at the end of the optimal timeframe, and applying full mineral fertilizer. However, in a number of production situations, the tillage depth needs to be increased.

In areas with a consolidated horizon and a slope of 5–6°, it is advisable to perform deep loosening before ploughing. Tillage with a ripper to a depth of 70–80 cm at intervals of 50–60 cm along the slope breaks up the compacted layer and improves the aeration regime. This enhances subsurface drainage, which prevents erosion and waterlogging in spring, ensuring a yield increase of wheat by 5–7 centners/ha.

How to overcome cloddiness and preserve moisture during dry periods

Soil cloddiness after stubble ploughing is the main reason for the loss of soil moisture. To ensure the furrow slice crumbles well, minimize the gap between harvesting crops and primary tillage. The sooner you get your ploughs into the field, the closer the soil moisture will be to the state of workability. If the top layer is dry, but moisture from rainfall has penetrated deeper, adjust the ploughing depth strictly according to the moisture penetration level.

• Yield reduction with minimum tillage — 5.6–5.9 centners/ha
• Optimal depth of standard ploughing — 20–22 cm
• Depth of pre-ploughing stubble peeling — 8–10 cm
• Increase from deep loosening on slopes — 5–7 centners/ha
• Increase from soil packing in a dry autumn — 3–4 centners/ha

For high-quality crumbling of dry or over-compacted soil, use a stepped field preparation technology. This will allow you to break up clods and prepare the seedbed without extra machinery passes.

1. Perform pre-ploughing stubble peeling to a depth of 8–10 cm (on the day of ploughing or in advance with heavy disc harrows) to loosen the top part of the furrow slice.
2. Include one disc implement battery directly in the ploughing aggregate to process the soil during ploughing.
3. Process the field after ploughing with disc harrows without an angle of attack.
4. Use rollers in an aggregate with a plough to compact the top layer and block moisture evaporation channels.

Packing arable land in an aggregate with a plough is especially important in years with a dry autumn, when soil moisture drops below the capillary break point. Compaction reduces the excessive porosity of the top layer and blocks diffuse water losses. On leached chernozems, this technique allows for uniform emergence at optimal times and provides a yield increase of up to 3–4 centners/ha by maintaining plant stand density.

Soil packing and the operation of combined aggregates

Packing arable land for winter crops provides a yield increase only during dry periods or in case of forced late sowing. If the autumn is wet and heavy rains occur after ploughing, this technological operation does not affect the yield of winter wheat. The main guide for taking rollers into the field is the moisture content of the topsoil.

The weight of the roller must be adjusted to the current condition of the topsoil. When the moisture content of the arable land is below 17–18%, the compacting effect of the implement decreases sharply, so the weight of the roller must be increased. You also have to increase the weight of the aggregate in case of high cloddiness and large fraction size. If the soil moisture is optimal (around the capillary break point) and the soil crumbles well, it is sufficient to use simple implements in the hitch with the plough:

• harrows in one or two passes;
• an obliquely set drag.

Combined tillage implements are excellent for high-quality stubble cultivation. Such a hitch combines a plough, an obliquely set drag made of angle iron, and a clod-crushing roller (for this, a side section of the ZKK-6A roller is used). In steppe regions, to improve the structure of the arable land, a disk battery or the working elements of spike-tooth harrows are additionally included in the implement. Such a combination of operations allows for preparing the field in a single pass and significantly saving resources.

Semi-fallow tillage and moisture conservation

The time between ploughing and the sowing of winter crops is used for semi-fallow field preparation. The main task during this period is to conserve soil moisture in the seedbed and provoke the germination of weeds and volunteer plants. The appearance of green seedlings of weeds in the field is a sure sign that there is sufficient soil moisture in the sowing horizon and that the accumulation of nutrients is proceeding correctly.

• Soil moisture for roller weighting — less than 17–18%
• Shallow cultivation depth — up to 6 cm
• Yield increase in northern zone experiments — 2–3 centners/ha

Tillage maintenance is carried out using cultivators hitched with harrows and drags. It is necessary to enter the field during the mass emergence of weeds and volunteer plants. It is extremely important to destroy annual and perennial weeds (for example, creeping thistle) before they form a large rosette and begin to accumulate nutrient reserves in the root system.

The cultivation depth should be minimal — no more than 6 cm, so as not to dry out the seedbed. It is only necessary to loosen the soil deeper in case of severe field infestation with perennials. In this case, as soon as the loosened layer is slightly aerated, the field must be compacted with light rollers to prevent moisture loss.

Special attention is paid to leveling the surface. Standard tooth harrows hitched with a cultivator handle this task poorly, so it is better to use drags made of obliquely set wooden beams, angle iron, or heavy chains. In steppe regions, during semi-fallow tillage, it is undesirable to operate with steam cultivators equipped with universal sweeps: they turn over the soil and leave ridges. It is safer to use flat-cutting sweeps or harrow-cultivators made from standard tooth harrows with welded segments from reapers.