Post-harvest tillage technologies for spring crops

After Harvesting of grain crops">harvesting grain crops, the field must not be left untreated even for a few days. Without the protective effect of the standing crop, the soil rapidly loses moisture and compacts, which hinders any subsequent work. On untreated stubble, late spring weeds quickly set seed, and perennials begin to actively accumulate nutrients in their roots. In addition, pests and diseases continue to develop in the crop residues, increasing risks for future sowings.

To prevent these problems, prepare the soil immediately after the combine passes using one of three methods:

• carry out ploughing;
• perform immediate stubble cultivation;
• apply soil-protective technology — process the field with a spiked harrow or sweep cultivators.

Why stubble cultivation must be carried out immediately

Carrying out primary ploughing immediately after harvesting can be difficult, as most heavy tractors are busy preparing the soil for winter crops at this time. In such a situation, disc cultivation or processing with a disc harrow is the best solution. This technique creates a loose mulching layer on the surface, which stops moisture evaporation and encourages weed seeds to germinate. Also, cultivation cuts annuals, depletes perennial weeds, and destroys habitats for pests and diseases.

This technological operation should be considered emergency work that is carried out strictly following the harvest. Otherwise, the resources and time spent will be useless. For example, discing performed 20 days after harvesting no longer conserves soil moisture. During this time, the water reserves in the topsoil layer manage to drop below the wilting point.

• Minimum cultivation depth — 8 cm
• Critical period without treatment — 20 days
• Reduction of plough draft resistance — by 250 kg

How cultivation depth affects moisture and draft resistance during ploughing

The processing depth is selected based on the conditions of a specific farm, the level of weed infestation, and the density of the field. According to field test results on leached chernozem, shallow cultivation at 4–5 cm does not ensure moisture retention in deep soil layers. 21 days after shallow discing, soil moisture remained practically the same as on untreated stubble plots. To reliably conserve water and effectively cut weeds, the processing depth must be at least 8 cm.

The earlier cultivation is carried out after harvest, the more effectively it can be performed. Moist soil crumbles well, and the use of sharpened discs with an increased angle of attack allows for a crumbling depth of about 8 cm even in arid steppe regions. If the topsoil is severely desiccated and disc cultivators cannot penetrate, the field should be treated with disc harrows or sweep cultivators. In regions with insufficient moisture, the efficiency of weed control is increased by packing, which improves seed-to-soil moisture contact and stimulates mass germination.

On leached chernozem, preliminary cultivation at 8–10 cm reduces draft resistance during ploughing by 250 kg compared to shallow processing at 4–5 cm. This allows for savings in fuel and machinery service life. Indicators of soil specific resistance during ploughing depending on cultivation are presented in the table.

If a field is heavily infested with perennial root-suckering weeds, the depletion method is used in the system of autumn ploughing. It is aimed at destroying weeds by systematically cutting them. To do this, the following sequence of operations is performed:

1. Carry out several consecutive cultivations with deep weed cutting.
2. Perform deep ploughing.

Control of root-suckering weeds: cultivation system and herbicides

Perennial root-suckering weeds require systemic depletion. When weeds are cut at a depth of 20 cm, only one or two shoots regrow, whereas with shallow cutting, 23% of weeds form three to four new shoots. Multiple treatments before autumn ploughing significantly reduce weed infestation. For example, three preliminary cultivations instead of one reduce the number of weeds in sunflower crops in the spring by three times, and by the time of harvest — by six times.

• Reduction of weed infestation by harvesting — 6-fold
• Depth of disc stubble loosening — 6–8 cm
• Depth of ploughing after glyphosate application — at least 27 cm
• Herbicide action period before ploughing — 20 days
• Threshold for reduced glyphosate efficacy — 12–14 °С

In fields infested with root-suckering weeds, it is recommended to carry out two or three sessions of variable-depth stubble loosening. Intervals between treatments are timed to the mass emergence of weed seedlings. For effective weed depletion, the following sequence is used:

1. The first disc loosening is carried out immediately after the harvesting of the previous crop to a depth of 6–8 cm.
2. The second loosening is performed using a mouldboard implement or a flat-cutter as soon as seedlings appear, to a depth of 8–12 cm.
3. The third loosening (under favorable conditions) is carried out to a depth of 10–14 cm.

Each treatment with a mouldboard loosener must be combined with rolling or harrowing. This reduces soil moisture losses and triggers weed seed germination. To protect soil from wind erosion in the ordinary chernozems of the northern zone, a needle harrow is used immediately after harvesting the crop — it loosens the top layer while leaving stubble on the surface.

For mixed-type infestation, a chemical control scheme is effective. Immediately after harvesting, the stubble is loosened to a depth of at least 8–10 cm using mouldboard looseners, disc harrows, or flat-cutting cultivators. After the mass regrowth of rosettes, weeds are sprayed with glyphosate. The preparation penetrates the root system of young shoots, and after 20 days, when its effect is visible, deep ploughing is carried out to a depth of at least 27 cm.

Depth of winter ploughing and distribution of weed seeds

After harvesting grain crops, about 80% of weed seeds are concentrated in the topsoil layer. Primary tillage allows this reserve to be moved to a depth where germination for most species becomes impossible. The effectiveness of this technique directly depends on the biological characteristics of weed seeds and their burial depth.

Small seeds, such as those of whorled clary, redroot pigweed, and creeping thistle, are capable of germinating only from a depth of 2–4 cm. Large-seeded weeds emerge from deeper layers as well, but a depth of 20 cm is critical for all major weeds.

A standard plough is insufficient for effectively moving seeds to the bottom of the furrow. Using a plough with an extended jointer and a furrow cleaner allows for reliable localization of the maximum number of seeds in the lower soil layer, where they lose their viability.

Increasing the depth of ploughing leads to a sharp decrease in the number of annual and perennial weeds.

It has been proven that deep winter ploughing against the background of two preliminary loosenings increased the mortality rate of root-suckering weeds.

Table 9 – Influence of ploughing depth on the mortality of perennial weeds, %

Increasing the depth of ploughing has less impact on perennial weeds than on annuals. One should not think that by increasing the ploughing depth, the infestation of fields with perennial weeds can be sharply reduced in just one year. However, this practice has a more significant impact if applied as part of a complex of measures to reduce weed infestation of fields by weeds of this group.

Weed control will be more successful if deep ploughing is carried out periodically, every three to four years. If it is repeated more frequently and at a constant depth, the weed seeds deposited at the bottom of the furrow during the first deepening will end up in the upper part of the arable layer and will infest the crops.

In the Kuban region, non-mouldboard ploughing with a T. S. Maltsev plough and a standard plough with removed mouldboards was widely studied. Comparing mouldboard deep ploughing with deep non-mouldboard (Kuznetsov I. A., Dubonosov T. S., Yaroslavskaya P. N., A. Ya. Maksimova, et al.), they noted significantly higher infestation in the latter, especially with annual weeds. The number of weeds with non-mouldboard tillage was several times higher than in the control. Even more weeds were present with surface tillage. The danger of heavy crop infestation became one of the reasons why such tillage was not recommended.

Increasing the ploughing depth is one of the important means of controlling pests and diseases of crop plants.

With deep cultural ploughing, especially on heavy chernozem soils, the physical properties of the soil improve. In chernozem soils, the structural composition of the upper part of the arable layer is improved. I. A. Kuznetsov noted an increase in the water stability of aggregates by 7–8% on leached chernozems when the ploughing depth was changed from 20 to 30 cm.

It has also been established that the percentage of water-stable aggregates in the 0–15 cm layer increases from 54 to 72 when the ploughing depth is increased from 22–25 to 30–32 cm. However, it should be noted that such an improvement in structure with deep ploughing using a plough with a jointer occurs only on chernozem soils.

On soils with a shallow arable horizon (for example, grey and dark grey forest soils), an increase in ploughing depth led to a deterioration in the structural composition.

Improvement of the structural composition and total porosity during deep ploughing promotes better water penetration into the soil, which is especially important for heavy, compacted soils. Increasing the ploughing depth promotes an increase in total porosity and a decrease in its capillary fraction.

In the upper part of the leached chernozem profile under sunflower crops, for example, by deepening the winter ploughing from 22–25 to 30–32 cm, the total porosity increased from 49 to 53% and remained noticeable for two years from the time of deep ploughing.

When using non-inversion tillage implements instead of a plough, the total porosity of the arable layer under crops decreases slightly, but remains within the optimal values for soils in the steppe part of the region.

Deep ploughing increases the looseness of the topsoil, improves its water capacity and water permeability, as a result of which the spring moisture reserve increases slightly. At the same time, the influence of ploughing depth in the zone of leached chernozems is less pronounced in rainy, warm winters, when the soil profile wetting process continues throughout the cold period. Deep ploughing has a stronger effect in cold, frosty winters, which are characterized by intensive wetting of the soil mass only with the onset of spring. Under these conditions, higher water permeability is manifested in fields with deep mouldboard ploughing.

On average, over three years of experiments on leached chernozem, deep ploughing provided an increase in moisture accumulation by spring of 19 mm. With deep non-inversion ploughing, on average, less moisture accumulated by spring than with deep mouldboard ploughing. Increasing the depth of mouldboard ploughing on chernozem soils improves their nutritional regime due to an increase in the total amount of mobile nutrients.

This is a consequence of a positive change in the structure of the deeper arable layer. In the 0–45 cm layer with deep ploughing during sunflower flowering, 47.5 mg of nitrates per 1 kg of absolutely dry soil was recorded, compared to 34.7 mg with ploughing at 22–25 cm. A decrease in the amount of nitrate nitrogen was noted when the main deep (up to 45 cm) tillage was carried out without turning the soil slice. The amount of nitrates with deep non-inversion tillage was almost the same as with conventional mouldboard tillage to a depth of 20–22 cm.

By using subsoilers attached to conventional cultural ploughs, it is possible to increase the depth of the arable layer by 15–17 cm. However, this method does not produce a positive effect on all soils of the Kuban.

One should not expect results from the use of subsoilers on soils that have a good structure in the sub-arable layer. Ordinary and typical chernozems and chestnut soils are characterized by quite high porosity below the arable horizon. The total porosity in this layer is not less than 49–50%. Such porosity is not lower than the optimal interval for crop plants. In its time, experiments on ordinary chernozems in the northern zone of the region proved the ineffectiveness of using subsoilers for spring crops.

A completely different result is provided by the use of subsoilers on heavy soils in the southern foothill zone. Compacted chernozems, grey and dark grey forest soils, and heavy meadow soils have significant compaction in the sub-arable layers. The total porosity in them can decrease to 44–46%, i.e., it is below the optimal density values for crop plants.

The tines of the subsoiler loosen the compacted soil layer 15–17 cm below the plough share's path. Its total and especially non-capillary porosity increases, and air permeability improves. The use of subsoilers on soils with a shallow arable layer (for example, on grey forest soils) allows for an increase in the depth of the cultivated horizon.

On heavy soils in the southern foothill zone, plants suffer almost every year in spring and winter from an excess of water in the upper horizons. Therefore, practices that improve the drainage of excess moisture in the winter-spring period are included in soil tillage practices.

One of them is mole drainage. Since mass-produced implements for this practice are not supplied to the region, farms manufacture them themselves. The mole drainage implement is attached to the heel of the middle plough body. The drain diameter is 6 cm, the depth is 50 cm, and the distance between drains is 105 cm.

A condition for the efficiency of mole drainage is a slight slope of the terrain in the direction of ploughing to ensure the drainage of excess soil moisture from the upper soil layers.

Mole drainage is also effective on leached chernozem under irrigation.

Another means of reducing excess water during the winter-spring period and improving the physical properties of soils with a compacted, fused horizon is the use of subsoilers in the primary tillage system.

Deep non-inversion loosening can be carried out after stubble cultivation in the second half of summer or in autumn on grey forest soils and fused chernozems. A slight slope in the direction of loosening is essential.

The subsoiler operates at a depth of 70–80 cm. The distance between its passes should be 50–60 cm. After loosening, standard ploughing is carried out across the direction of the passes. The compacted soil layer is loosened, winter-spring surface water runoff is converted into subsurface drainage, soil profile aeration is improved, its water saturation is reduced, and the nutrient accumulation process is enhanced.

As a result of water drainage in the spring, it becomes possible to start field operations earlier.

On fused chernozems, deep loosening against the background of applying 20 and 50 t/ha of manure provides an average yield increase of corn over three years of 5.7 and 11 centners per 1 ha, respectively. Its effect persisted for two years on the yield of subsequent crops.

One of the means for deepening the arable layer is trenching. Under the region's conditions, trench (extra-deep) ploughing for field crops does not increase yield. However, after trench ploughing, weed infestation is significantly reduced for a long time.

But if one compares the overall efficiency of trench tillage with standard deep ploughing at 30–35 cm, extra-deep ploughing has no advantage. Its residual effect does not exceed that of deep ploughing, while the costs are significantly higher.

In view of this, it can be concluded that extra-deep ploughing for field crops on Kuban chernozems is not promising. Scientific institutions in the Kuban have studied surface tillage for spring crops. On leached chernozems, the corn yield with mouldboard ploughing was 50.5, and with surface tillage – 46.4 centners/ha.

On ordinary chernozems of the northern zone, the average corn grain yield over two years with mouldboard ploughing at a depth of 25–27 cm was 33.3, and with surface tillage at 10–12 cm – 25.2 centners/ha. Significantly greater weed infestation of crops was noted with surface tillage, especially with perennial weeds.

When choosing the depth of primary tillage, one should take into account the natural qualities of the soil, the depth of the humus horizon, and the soil fertility of the upper part of the soil profile. Some soils of the region (grey forest, humus, carbonate, brown forest, as well as meadow soils) have an insignificant humus layer, and deep ploughing can lead to turning up the infertile horizon to the surface, which means a significant decrease in yield. Here, the ploughing depth should not exceed the depth of the humus horizon.

However, even on such soils, one should strive to increase the depth of the cultivated layer. This can be achieved by periodically deepening the arable layer by 3–4 cm with the simultaneous application of large doses of manure combined with mineral fertilizers.

If it is necessary to increase the looseness of the sub-arable layers in such soils, soil subsoilers are used.

For the chernozem soils of the Kuban, there is also a limit to the rational depth of ploughing for field crops. Numerous field experiments and practice have established that annual crops on chernozems in the steppe regions of the region do not increase yield when the ploughing depth is increased beyond 30–35 cm. It should be emphasized that this concerns the direct effect of deep ploughing, not its residual effect.

The fact that annual crops on the region's chernozems do not increase yield with an increase in ploughing depth is determined by the nature of these soils. Despite the high nutrient content in the sub-arable layer, its effective soil fertility and activity are lower than those of the arable layer.

With extra-deep ploughing, the soil fertility of the sub-arable layer turned to the surface has a negative impact on the overall soil fertility of the deeply tilled layer. For this reason, there is no direct positive effect from ploughing to a depth of more than 35 cm.

The plant response to increased ploughing depth also depends on the natural structure of the sub-arable layer. On soils with a naturally relatively loose structure, it will decrease.

In the regional conditions on ordinary chernozems having a loose soil profile structure, the effect of deepening is obviously smaller for this reason than on leached ones. The choice of the depth of primary tillage also depends on how a given crop reacts to direct deepening or its residual effect. High efficiency of deep mouldboard ploughing has been established for sugar beet.

On ordinary chernozems, with an increase in ploughing depth from 20–22 to 27–30 cm, the yield increase of sugar beet reached 66 centners per 1 hectare. On chernozems in the Rostov Region, after ploughing to 20–22 cm, an average of 210.4 centners was obtained over six years, while where the depth was increased to 30–32 cm, 242 centners of roots per 1 hectare were obtained. On the leached chernozem of the Kuban, the yield increase of sugar beet from increasing the ploughing depth to 35 cm averaged 72 centners per 1 hectare. However, on both ordinary and leached chernozems, further increases in ploughing depth and the use of trenching ploughing are not accompanied by a noticeable increase in the yield of this crop.

It has been established that on leached chernozems, an increase in ploughing depth slightly improves the yield of sunflower.

In years with favourable weather conditions during the seed formation period, the yield increase from deep ploughing rises. Under production conditions on heavily weed-infested fields with deep ploughing, the increase reached 2–3 centners per 1 hectare.

Crops that respond to an increase in ploughing depth can also include maize, perennial grasses, and vegetable crops. The yield of maize increases when the ploughing depth is increased to 30 cm. Deeper ploughing has practically no effect on the yield on both compacted and leached chernozems.

When choosing the tillage depth for a specific crop, one should consider the residual effect of previous deepenings of the arable layer, the influence of which is not limited to the crop for which they were performed. The duration of the effect of deep ploughing is determined by the soil texture (the heavier it is, the shorter the duration period) and weather conditions (the more precipitation, the shorter the duration of the deepening effect).

Research on leached chernozems has established that an increase in ploughing depth to 30–32 cm has a positive impact on the harvest over several years, providing a total yield increase of grain and oilseed crops of 10–12 centners per 1 hectare over these years. In this regard, it is recommended to carry out deep tillage in the leached chernozem zone every three to four years, and on ordinary ones every four to five years. Such periodicity of ploughing deepening on fields clear of perennial weeds, but infested mainly with annual weeds, allows for obtaining the highest sum of yields and profitability per 1 hectare.

In the period between deep ploughings for spring crops, ordinary tillage to 20–22 cm should be conducted, and for winter crops, depending on the situation, to 8–10 or 18–20 cm. With the introduction of effective herbicides into production, it has become possible to minimize soil tillage.

Ploughing to 20–22 cm for oilseed crops, to 30–32 cm for sugar beet, surface tillage for winter wheat. Herbicides were used on all crops (ordinary tillage with herbicides).

Ploughing to 12–14 cm for all row crops and disc stubble cultivation for winter wheat. Herbicides were used on all crops (minimum tillage with herbicides).

Ploughing to 12–14 cm, but without herbicides on all row crops (minimum tillage without herbicides).

Minimum tillage did not cause significant soil compaction compared to ordinary tillage and did not lead to a deterioration of water and nutrient regimes. With minimum tillage without the use of herbicides, the weed infestation of all row crops was five to fourteen times higher than where they were used.

The application of a soil herbicide reduced the weed infestation of oilseed crops, but even in this case, with shallow tillage, there were 10–60% more weeds than with ordinary tillage. The greatest negative impact of weed infestation was manifested in soybean and beet crops, which competed poorly with weeds.

Minimum primary tillage with the application of herbicides contributed to a reduction in its potential weed infestation by weed seeds by almost six times.

The yield of sunflower, as the most competitive crop in relation to weeds, on average practically does not depend on the use of herbicides under minimum tillage. However, with surface tillage, costs were noticeably reduced.

Castor bean and soybean, being more sensitive to weed infestation, saw their yields reduced under minimum tillage without the use of herbicides by 42% and 30%, respectively.

The highest sugar beet yield was obtained with ordinary soil tillage to a depth of 30–32 cm. Under minimum tillage, if herbicides were applied, the yield decreased by 11%, and without them by 28.8% compared to ordinary tillage. On cultivated fields where perennial weeds are absent, it is recommended when using highly effective herbicides to apply tillage with a share stubble plough to a depth of 12–14 cm in the grain-row crop rotation for sunflower and soybean. For beet, ploughing should be carried out to a depth of 30–32 cm, and for winter wheat after row crop predecessors, surface tillage to 8–10 cm.

Experiments on ordinary chernozems have also shown the possibility of replacing ploughing with non-inversion loosening to a depth of 12–14 cm, provided that highly effective herbicides are used.

Scientists in the Stavropol Territory have reached similar conclusions based on research conducted over eleven years on chernozems in the zone of unstable moisture.

In cases of low infestation with perennial weeds under crops occupying fallow fields – peas, sunflower – the depth of primary tillage can be reduced to 12–14 cm. Deep ploughing to 30–32 cm is recommended only for sugar beet. The timing of winter ploughing should be considered. Its choice is influenced by the specific conditions of a given farm and even the field itself.

When choosing the timing for winter ploughing, it is necessary to take into account, first of all, the capacity of the tractor fleet and its workload during the autumn period for other operations. When drawing up a ten-day schedule for winter ploughing, a specialist must realistically account for the farm's capabilities, ensuring the completion of soil preparation for winter crops prior to their sowing, harvesting of row crops, and ensiling. The schedule should be calculated to finish winter tillage by the likely onset of autumn muddy conditions, i.e., in the first ten days of November.

The species and quantitative composition of weed plants in a given field also determine the choice of timing for winter ploughing. Fields infested with perennial weeds, especially root-sprouting ones, should be ploughed later. It is necessary to plan for the exhaustion of weeds through shallow tillage or to combine such treatments with the application of herbicides prior to ploughing. The number of treatments and their depth should be adjusted according to the quantity of weeds.

The soil texture and the average amount of precipitation occurring during the moisture-accumulation period must also be considered when choosing the timing for winter ploughing.

Heavy soils in southern regions containing large amounts of silt and clay (leached and compacted chernozems, grey forest, and heavy meadow soils), where significant precipitation occurs during the autumn-winter period, become highly compacted and waterlogged. A reasonable delay in the timing of ploughing in these regions leads to less compaction of the winter-ploughed field by spring. It should be emphasized that under farm conditions, the timing of winter ploughing should be delayed so as to complete it before the onset of autumn inclement weather.

In experiments on heavy grey forest soils, a grain corn yield was obtained, averaging over four years, which was 11.2 centners per hectare lower with July winter ploughing compared to October ploughing.

Primary tillage in a given field must be planned as a system of measures that meets the soil and climatic conditions of the farm, the general state of the field at the time of harvesting the predecessor, and weather conditions. Soil tillage in a given field should be linked to the tillage system adopted in the crop rotation and based on consideration of the cultivation agrotechnics of the predecessors and the aftereffect of its methods.

When choosing a stubble tillage system, several factors should be considered.

Firstly, this system must always include stubble discing or treatment with a needle harrow immediately after mowing small grains to a depth of at least 6–8 cm. It is desirable to perform this first stubble treatment with disc harrows or needle harrows to increase productivity. Subsequently, the choice of specific soil tillage methods must be carried out strictly in a differentiated manner, taking into account the soil and climatic conditions of the farm, the situation in the field, the weather at the given moment, and the workload of the tractor fleet.

In all zones of the territory, in heavily infested fields with a predominance of perennials, especially Canada thistle, field bindweed, and Cynanchum acutum, a winter stubble tillage system should be planned. It includes:

• several discings or treatments with sweep cultivators as weeds regrow;
• winter ploughing in late September–October.

Such a soil tillage system allows for a significant reduction in the infestation of crops with perennials. In this process, two or three stubble discings are performed. The time of their execution is determined by the mass regrowth of weed plants. Following the first, the second and third discings are performed with a mouldboard implement or a sweep cultivator, each at an increasing depth:

To improve conditions for weed germination, discing should be accompanied by measures that ensure a reduction in water losses (packing). In many farms of the region, mouldboard discing is replaced by shallow ploughing to 16–20 cm with harrowing and packing.

At the same time, the use of a plough instead of a mouldboard disc harrow does not provide noticeable advantages in reducing weed infestation. Shallow ploughing to a depth of 16–18 cm before primary winter ploughing has the same effect on root-sprouting weeds as two discings followed by ploughing. However, in practice, a plough is often used instead of a mouldboard disc harrow – the plough is better at processing dry, compacted soil.

Weed infestation in sugar beet crops is reduced by three to four times when using several stubble stubble-ploughings. If the field is significantly infested with perennial weeds, it is advisable to increase the depth of ploughing, even if the crop for which the winter tillage is being conducted does not respond to deepening of the arable layer.

In the southern foothill zone on fused chernozems, gray forest soils, as well as on heavy variants of meadow soils and soils of steppe depressions, which become highly self-compacting by spring, as previously mentioned, a reasonable delay in the date of winter ploughing is desirable. Before it is carried out, the field should be stubble-ploughed as mass emergence of weed seedlings occurs. Stubble-ploughing can only be disc-based if the plot is infested with annual weeds. In the presence of perennials, mouldboard stubble-ploughs, flat-cutters, or shallow ploughing of the field are used.

If, in this zone, ploughing is completed early and by the end of autumn the soil has become compacted due to precipitation, it is beneficial to re-plough it at a later date to a depth of 14–18 cm.

In the steppe regions of the territory on common and leached chernozems, as well as chestnut soils, it is possible to use so-called semi-fallow tillage, i.e., carrying out stubble-ploughing following an early harvest (usually in August), ploughing with leveling of the arable surface using a harrow or a drag, and packing the arable layer with a roller, followed by autumn soil care as weeds emerge.

This tillage system is possible in cases where the field is not infested with perennial weeds and, crucially, if the soil crumbles and breaks up well during early ploughing. Only with good breaking and crumbling of the arable layer does the semi-fallow tillage system realize its advantages in the steppe regions of the territory, meaning it will contribute to moisture conservation and accumulation better than late ploughing.

Cloddy, ridged, and uncultivated arable land will lose more moisture during a dry autumn, and by spring, it will have accumulated less water than conventional winter ploughing. The effectiveness of semi-fallow tillage for beets is increased by autumn re-ploughing of the semi-fallow at 14–16 cm. Such a technique reduces the density of the arable layer and its cloddiness during spring tillage.

The quantity of weeds after autumn re-ploughing is reduced by half, and the average yield increase of beet root crops over seven years reached 22 c per 1 ha. On leached chernozems, the average increase in beet yield from autumn re-ploughing of the semi-fallow over three years amounted to 60 c per 1 ha.

It should be noted that autumn re-ploughing of early winter ploughing somewhat increases its wind resistance during dust storms. The semi-fallow tillage system is a powerful means of controlling annual weeds. However, it will only fulfill this task if conditions for weed germination are optimal during the summer-autumn period, i.e., if there is sufficient soil moisture in the upper part of the arable layer.

The combined winter tillage for beets, once proposed, has proven the advantage of this system for regions with insufficient moisture through many years of experiments. In these regions, late summer and autumn are usually dry, with little precipitation. Conditions for the effective application of semi-fallow are often absent.

Therefore, combined tillage (two to three stubble-ploughings and ploughing in October) ensures, on average, a slightly higher moisture reserve by the start of sowing spring crops. By spring, such fields will have a looser structure, and therefore less cloddiness during spring tillage.

Furthermore, combined tillage under dry summer-autumn conditions ensures more successful weed control than semi-fallow. This increases the yield of root crops. On average, over 17 years, 383 c per 1 ha were obtained with such tillage, while 368 c per 1 ha were obtained with semi-fallow.

In our view, one should not provide categorical recommendations on the use of one or another soil preparation system for spring crops in the conditions of the territory's steppe zone.

It is determined by the situation in the field and the weather conditions of the summer-autumn period. Furthermore, most farms will be unable to choose only one type of tillage due to an increased need for tractors over a rather short period. At the same time, due to the usually dry weather in the summer-autumn period, combined tillage is more often applied in the insufficiently moistened regions of the northern zone of the territory. This system should also be preferred because the topsoil layer remains more wind-resistant entering the winter after its completion.