Soil Tillage for Spring Crops

Fall Tillage

Fall soil tillage is tillage in the summer-autumn period for sowing spring crops the following year. It may include one or several operations performed in a certain sequence. The operations of fall tillage depend on soil and climatic conditions: moisture supply of the zone, soil type, texture, thickness of the arable layer, likelihood of erosion, crop response to tillage depth, preceding crops, soil infestation with weeds and other conditions.

Depending on the preceding crops, degree of field weed infestation and technological properties of the soil, the following types of fall tillage are distinguished:

• after annual continuous-sown crops;
• after row crops;
• after seeded perennial grasses;
• semi-fallow soil tillage.

Soil Tillage after Annual Continuous-Sown Crops

Annual continuous-sown crops, for example, winter rye, barley, winter wheat, peas, etc., are harvested early and leave the field early. In the absence of plant cover, the soil dries strongly, which leads to significant moisture losses by evaporation. During drying and under the running systems of harvesting machinery, soil compaction occurs. Autumn precipitation is poorly absorbed by compacted soil, which leads to surface runoff and losses. The long post-harvest period promotes the growth and reproduction of weeds. Stubble remaining in the field and vegetating weeds serve as reservoirs for overwintering pests and pathogens, creating infection foci. Under these conditions, the main task of the soil tillage system for spring crops is to prevent drying, destroy vegetating weeds and incorporate their shattered seeds into the moist layer.

Typical soil tillage after annual continuous-sown crops consists of stubble cultivation and subsequent fall plowing with moldboard plows with skimmers. It allows incorporation of weeds and their seeds, fertilizers and ameliorants and prepares the soil for early sowing of spring crops. Plowing gives the arable layer a loose crumbly structure, ensuring optimal conditions for accumulation and conservation of autumn and winter precipitation water. The advantage of fall plowing compared with spring plowing has been proven in most regions of Russia. Only under conditions of a short post-harvest period and snowless windy winters is it more expedient to move plowing as the main tillage operation to spring. An unplowed field in autumn in these regions, with stubble left, dries less and accumulates more moisture.

The dates of stubble cultivation and fall plowing depend on crop harvest time, duration of the warm post-harvest period, soil moisture and emergence of mass weed seedlings. For most regions of the country, early fall plowing is effective, providing the most favorable conditions for decomposition of plant residues, organic fertilizers and nutrient accumulation. According to generalized experimental data, the early date of fall plowing is considered for the north and east of Russia to be the period before September 5; for the Central part of the Non-Chernozem zone, Central Chernozem zone and Middle Volga, before September 20; in the south it is carried out even later. The post-harvest period with a temperature above 10 °C in most of the listed regions lasts more than one month, which is sufficient for weed control. Thus, annual weeds with sufficient heat and water germinate in 15-20 days, perennial ones in 23-30 days, which often determines the dates of fall plowing. In the north, northwest, Eastern Siberia and other regions with a short growing season, plowing is performed immediately after cereal harvest, without preliminary stubble cultivation.

Early fall tillage in the south of Russia under a long post-harvest period allows 1-2 additional cultivations or stubble cultivations before winter. In dry weather, plowing is done with a plow in a unit with a ring-spur roller, which helps conserve moisture and provoke weed germination.

The depth of autumn plowing is determined depending on the thickness of the humus layer, soil type, crop requirements, weed infestation and species composition of weeds.

For sod-podzolic and gray forest soils with annual weeds for spring crops, plowing is done to a depth of 16-17 cm; with perennial weeds, up to 20-22 cm. For row crops on chernozems and gray forest soils, plowing is performed to 28-32 cm. Deep plowing is effective in excessive moisture areas, ensuring the possibility of water removal through the sub-arable layer.

Deep autumn tillages create excessive soil looseness and cause waterlogging, resulting in a delay in sowing early spring cereals and reduced yield. Therefore, on excessively moist soils, plowing is replaced by shallow tillage to a depth of 10-12 cm using heavy disk harrows or share stubble cultivators. Such tillage is effective for late-sown crops and row crops, for which plowing is done in spring.

In areas of sufficient moisture, fall plowing is carried out without harrowing. Ridgey plowland reduces compaction of the upper layer, promotes snow retention, protects the soil from deep freezing, and in spring the ridges warm better. Conversely, in steppe arid regions and Eastern Siberia with snowless winters, plowing is done with simultaneous leveling of the surface with harrows and rollers to avoid soil drying. In wind erosion risk zones, autumn tillage is done with flat-cutting subsoilers to 16-18 cm while leaving stubble on the surface.

For row crops and in clean fallows, the tillage depth is up to 25-27 cm. It is carried out with no-moldboard plows such as paraplow or those equipped with SIBIME tines.

On non-weedy and weakly compacted soils, for example, after cereals following clean fallow or row crops, autumn plowing is done to a shallow depth with flat-cutters; compacted soils are treated to a depth of 25-27 cm with flat-cutters and subsoilers.

After harvesting cereals or grain legumes, or immediately during harvest, the field is stubble-cultivated with disk or share stubble cultivators to a depth of 5-7 cm; in arid conditions, to 8-10 cm. When fields are infested with rhizomatous and root-suckering weeds, stubble cultivation is performed to 12-14 cm, repeating it in the transverse direction. The main task of stubble cultivation is incorporation of shattered weed seeds into the soil, chopping rhizomes and stimulating their germination. After mass weed seedlings appear, plowing is done to a depth of 20-22 cm with a moldboard plow with skimmers. On soils with a shallow arable layer, plowing is done to its full depth with a subsoiler. With such tillage, the skimmer cuts weeds and drops them to the bottom of the furrow together with pests and pathogens in the upper soil layer; the main plow body lifts the lower soil layer and covers the furrow. In conditions of a short and dry summer-autumn period, stubble cultivation is not done, since weed seeds may not germinate and the effect will be absent. In this case, immediately after harvesting the preceding crop, deep fall plowing is done. Usually fall plowland is not harrowed in autumn, but left for winter in a ridged state.

In areas subject to wind erosion, for example, the Southern Urals and Western Siberia, ordinary plowing is replaced by flat-cutting fall tillage, while most of the stubble remains on the soil surface, protecting the soil from wind, promoting snow retention, less soil freezing and rapid thawing in spring. For effective weed control in this case, deep flat-cutting tillage is combined with surface tillage.

In the Non-Chernozem zone on soils with a small humus layer, deepening of the arable layer to 25-30 cm with simultaneous application of organic and mineral fertilizers is important, primarily for spring wheat. Deepening is done in fallow and during fall tillage for preceding crops.

Features of Soil Tillage after Row Crops

Row crops have late harvest dates; the soil under them is often tilled deeply, and the freed fields are in a relatively clean state from weeds with sufficiently loose soil and a favorable nutrient regime. Autumn plowing, for example, after potato and root crops, is replaced by share stubble cultivation to a depth of 10-14 cm or no-moldboard loosening. Or plowing is done without preliminary stubble cultivation. With poor row crop care, stubble cultivation before fall tillage is more important as an agronomic weed control practice. In this case, after potato and sugar beet, it is recommended to treat with share stubble cultivators to a depth of 10-12 cm. On heavy and strongly settled soils clean of weeds, deep plowing without stubble cultivation is done.

In the Non-Chernozem zone, row crops are harvested quite late, so after their harvest stubble cultivation is usually not done. Compacted wheel tracks (roads) formed in the field during harvest are disked twice or plowed in.

On heavy soils and with strong infestation of the field with perennial weeds, plowing is done with moldboard plows with skimmers. After tall row crops, for example, maize, sunflower, sorghum, coarse plant residues of stems remain in the field; to chop them, disking with heavy disk harrows in 1-2 passes is done or root-stem choppers and rotary cultivators are used. Then plowing with moldboard plows with skimmers is done.

On medium and well-cultivated medium loamy soils and fields weakly infested with perennial weeds, plowing for spring cereals is replaced by shallow tillage to 10-12 cm using disk stubble cultivators or heavy harrows such as BDT-3, BDT-7, BDT-10, heavy fallow cultivators KPE-3.8, KTS-10-01, and chisel cultivators KChP-5.1.

Surface or shallow tillage after row crops with wide-cut implements allows reducing the number of machinery passes, reducing soil compaction, and conducting spring field work 3-5 days earlier for early-sown crops.

The choice of primary tillage operations should take into account the degree of field weed infestation, soil type and risk of erosion. For example, on light soils at risk of wind erosion, the soil is treated with flat-cutting implements to a depth of 12-14 cm or the field is left untreated. The tillage depth of heavy soils is increased to 20-22 cm. For shallow tillage, cultivators-flat-cutters such as KPSH-5, KPSH-9, KPSH-11, OPT-3-5 are used.

In arid conditions on soils clean of weeds, after row crop harvest, plowing is better replaced by no-moldboard tillage.

On solonetzic compacting soils and slope lands, deep flat-cutting or chisel loosening to a depth of 25-27 cm or ripper plows with inclined tines such as paraplow or SIBIME tines are used. Fields infested with wild oat (Avena fatua), to provoke its seedlings, are preliminarily treated with needle implements such as BIG-3A, BMSH-15, BMSH-20.

Soil Tillage after Seeded Perennial Grasses

Soil after cultivation of perennial grasses for 3-4 or more years, especially in grass-field soil-protecting crop rotations and out-of-rotation fields, remains more coherent, strongly dried, and the upper layer is densely interlaced with living and dead plant roots.

The upper soil layer, penetrated by roots, is well structured and has increased coherence. Often fields from perennial grasses are infested with perennial weeds, and the sod is capable of regrowth. For these reasons, the main tasks of tillage of fields after perennial grasses are depriving the sod of viability, improving the air regime and soil aeration, and creating favorable conditions for decomposition of plant residues.

Depending on the composition of vegetation and duration of perennial grass use, the following types of sod are distinguished:

• grass sod layer after breaking up seeded perennial grasses;
• long-term abandoned land, or long fallow, that is, an area previously cultivated but then left without tillage and overgrown with wild vegetation;
• virgin land, or natural sod, that is, not previously tilled or tilled very long ago.

The quality of these sod types differs and requires a differentiated approach to their tillage.

In regions with a short growing season, fields after seeded perennial grasses are plowed with moldboard plows with skimmers. For good covering of the sod with loose soil, the skimmer is set to a depth of up to 12-14 cm. Quality incorporation of sod is achieved when plowing sod-podzolic soils to a depth of not less than 20-22 cm, chernozems to 25-27 cm. To avoid soil drying, accelerate decomposition of plant residues, and in the case of strong sod, after plowing disking, leveling and packing of the soil are done. Depending on the duration of the summer-autumn period and grass productivity, plowing is done after the first or second cutting. Early dates of sod plowing accelerate its decomposition.

Heavy and perennial weed-infested soils before plowing are disked in two directions to a depth of 8-10 cm using heavy disk harrows. This stimulates weed growth. When they regrow en masse, plowing with moldboard plows with skimmers is done, allowing 80% cleaning of the field from perennial weeds and preventing sod regrowth.

To prevent regrowth of alfalfa sod, the field is treated 12-15 days before plowing with share stubble cultivators or immediately plowed to 25-27 cm. Quality incorporation of the sod layer is ensured by plows with elongated skimmers.

Early dates of sod plowing promote sod decomposition and increase spring cereal yield by 12-15%. Therefore, in the north and east, plowing is done immediately after mowing perennial grasses. With good herbage, treatment is performed after the second cutting, increasing rotation productivity by 15-20%. In irrigated agriculture, several cuttings are taken; after the last one, plowing is done.

The sod layer for winter wheat is plowed after the first cutting, and for spring crops, millet, flax and other spring crops, as a rule, after the second cutting. Heavy soils are plowed earlier than light ones. Fields with thick sod, especially after grass crops such as crested wheatgrass, are better treated earlier.

In a dry climate, the early date of sod plowing has the advantage; otherwise, delay leads to strong soil drying and reduced spring cereal yield. In the Non-Chernozem zone, no large differences in yield are observed with early and late sod plowing.

On peat and non-stony soils, dense grass sod before plowing is treated with rotary implements to 8-10 cm. Deeper rotary tillage is possible but involves high energy costs.

When placing spring cereals after perennial grasses, the soil is plowed to 20-22 cm; for row crops, simultaneously with plowing, the arable layer is deepened by 8-10 cm.

On light soils, due to strong aeration leading to accelerated decomposition of plant residues and nutrient loss, plowing is done later.

In the steppe zone, primary tillage is done as early as possible after the first cutting. In Altai Krai, according to the recommendation of ANIIS, a soil-water-protecting variant of the tillage system for perennial grass sod is being introduced, which consists in replacing plowing with deep flat-cutting tillage with thorough incorporation of sod by heavy disk harrows.

Semi-Fallow Soil Tillage

Semi-fallow soil tillage is a set of continuous tillage operations carried out after early-harvested non-fallow predecessors in the summer-autumn period. Non-fallow predecessors include winter rye, winter wheat, barley, maize for grain, buckwheat, etc. Semi-fallow tillage allows accumulation of an additional water reserve in the soil. Its main tasks are: preventing soil drying, improving tillage quality, weed control, and accumulation of water and available nutrients.

Semi-fallow tillage is widespread in the south of Russia, for example, in the North Caucasus, Middle and Lower Volga, where after harvest of early-harvested preceding crops 2.5-3.5 months of warm period remain, with significant precipitation. Thus, in Rostov Oblast autumn precipitation is 80-100 mm, in Krasnodar Krai 110-130 mm.

After non-fallow predecessors in the summer-autumn period, the soil is treated as clean fallow.

When determining semi-fallow tillage operations, the predecessor, moisture and soil compaction, and species composition of weeds are taken into account.

The most common variants of semi-fallow tillage are:

• plowing with moldboard plows with skimmers followed by periodic surface or shallow tillages throughout the post-harvest period;
• several stubble cultivations with disk or share stubble cultivators followed by late autumn plowing;
• flat-cutting 2-4-fold shallow tillages to a depth of 10-12 cm followed by deep no-moldboard loosening in late autumn.

Under conditions of sufficient soil moisture and weak weed infestation, after crop harvest plowing is immediately done to the depth of the arable layer with simultaneous harrowing and rolling. For this, a combined plowing unit such as PKA-2 is used, including a plow, rail drag, section of ring-spur rollers, which well loosens and levels the soil surface and creates a compacted layer at some depth preventing water evaporation. Such a tillage operation allows provoking uniform weed germination, which are destroyed by subsequent cultivations. The number of subsequent cultivations is determined by the degree of soil compaction and weed germination.

When the soil is dry or insufficiently moist after crop harvest, stubble cultivation is performed to a depth of 6-8 cm with simultaneous rolling with ring-spur rollers to provoke weed germination. With emergence of seedlings (after 2-3 weeks), plowing is done with simultaneous harrowing. In the subsequent period, several surface treatments with cultivators equipped with tooth or rod harrows, in dry weather with rollers, are performed.

In dry years, when the soil dries during plowing, a large number of clods forms, contributing to even greater evaporation of soil moisture. Therefore, plowing in such conditions is replaced by shallow tillage to 10-12 cm using heavy disk harrows or share stubble cultivators with simultaneous harrowing and rolling.

For more complete layer-by-layer destruction of root-suckering weeds, double stubble cultivation with simultaneous rolling is performed. The first is done with disk stubble cultivators to 8-10 cm, the second with share ones to 10-12 cm. When weeds regrow, the field is plowed with moldboard plows with skimmers and rolling is done. As the soil compacts and weeds germinate during the summer-autumn period, several cultivations with surface leveling are performed. When herbicides are used, the number of cultivations can be reduced.

For layer-by-layer cleaning of fields from perennial weeds, the depth is increased to 12-14 cm using wide-cut flat-cutting cultivators such as KPSH-5, KPSH-9, KPSH-11. The last deep tillage is performed in late autumn for cereal crops to a depth of 16-18 cm, for row crops to 25-27 cm. Treatment is done with flat-cutting subsoilers, for example, KPG-250, KPG-2-150.

Semi-fallow tillage has soil-protecting advantages, especially on heavy soils prone to sealing, and in the arid agriculture zone on saline chernozem and chestnut soils.

In steppe regions at risk of wind erosion and areas of insufficient moisture, instead of plowing, no-moldboard tillage is done with flat-cutting cultivators, subsoilers or chisel implements. In the case of annual weeds, instead of stubble cultivation, treatment is done with flat-cutting cultivators to a depth of 6-8 cm immediately after cereal harvest. Such tillage allows effective weed control while preserving up to 70% stubble on the field surface. As weed seedlings appear and the soil compacts, treatment is repeated throughout the post-harvest period.

Pre-Sowing Soil Tillage

Pre-sowing tillage consists in leveling the upper soil layer for quality seed placement, conserving soil moisture, cleaning from weeds and loosening to a specified depth.

Pre-sowing soil tillage can be:

• for early-sown crops, for example, oats, barley, spring wheat, vetch, peas;
• for late-sown crops: buckwheat, millet, maize, potato.

For pre-sowing soil tillage, tooth, disk, knife, needle and other harrows, fallow cultivators, rollers, rotary tillers, flat-cutting cultivators, as well as combined units performing several technological operations in one pass are used.

In early spring, as the soil dries, fall plowland is harrowed in two passes. After 2-3 days, treatment with tine cultivators to the seed sowing depth, usually 5-7 cm, with simultaneous harrowing is done. Sowing is performed the same or the next day. To reduce moisture losses in arid regions on clean and not strongly settled soils, cultivation is not done. In this case, sowing is performed immediately after harrowing.

To optimize soil conditions, accelerate seed germination and obtain uniform seedlings, a large gap between pre-sowing tillages and sowing must not be allowed, especially for early-sown crops.

In spring, fall plowland is re-plowed only in extreme necessity in areas of sufficient moisture. More often this is due to application of organic fertilizers, which for some reason were not applied under fall tillage. In spring tillage of heavy compacted soils, deep loosening of fall plowland with simultaneous harrowing gives good results.

In steppe regions of Siberia and the Southern Urals, to protect soils from deflation, flat-cutting soil tillage is performed using a needle harrow, then a flat-cutting cultivator.

Pre-Sowing Tillage in Zones of Insufficient Moisture

The main task of pre-sowing tillage in zones of insufficient moisture is leveling the soil surface and creating a mulch layer to conserve moisture. Therefore, in these conditions flat-cutting or needle implements that do not turn the soil are used. Organic fertilizers are better applied in autumn, whereas with spring application for row crops they are incorporated using heavy disk harrows to 14-16 cm. In the zone of insufficient moisture, selective early spring harrowing in 2-3 passes is done on the background of moldboard tillage; on the background of no-moldboard tillage, loosening with needle harrows or stubble cultivators with flat disks is used. After harrowing, when the upper layer reaches physical maturity, the soil is cultivated with simultaneous harrowing. In areas of insufficient moisture in Siberia, after harrowing one or two cultivations are done: the first 5-6 days after harrowing, the second before sowing.

Pre-sowing tillage of soils subject to wind erosion for early spring cereal crops in the steppe zone includes one harrowing with needle harrows BIG-3A in active loosening mode. Immediately after it, sowing with application of mineral fertilizers is performed using a stubble seeder SZS-2.1 and rolling. Before sowing, one pre-sowing cultivation with simultaneous harrowing to seed sowing depth is done. For cultivation, undercutting shares are used. Additional treatments in these conditions delay the sowing date, leading to yield reduction.

In steppe regions of Siberia, where autumn deep no-moldboard loosening was done, moisture is closed with needle harrows within 2-3 days after soil ripening. When warm days come, the field is treated with flat-cutting cultivators, if necessary, in combination with ring-spur rollers. With such treatment, part of the crop residues remains on the field surface.

Fields infested with wild oat (Avena fatua) and wintering weeds are first treated with needle harrows, then when wild oat regrows with flat-cutting cultivators such as KPSH-5, KPSH-9, KPSH-11 to 6-8 cm. When infested with perennial weeds, the number of cultivations is increased to two, and the depth to 12-14 cm. To reduce moisture losses by evaporation, the soil is simultaneously rolled.

In dry sunny weather, the gap between treatments should be no more than 3-4 h. For better soil crumbling, each subsequent treatment is done across the direction of the previous one, or at an angle of 45°. When closing moisture, it is better to use tracked tractors for less soil compaction. Pre-sowing cultivation is performed simultaneously with sowing sugar beet to a sowing depth of 4-5 cm.

On strongly compacted or perennial weed-infested fields, as well as fields after perennial grasses, deeper treatment with disk or moldboard stubble cultivators is used; on strongly sodded soils, 2-3-fold treatment. With spring application of organic fertilizers, the soil is treated with plows or share stubble cultivators to 14-16 cm; with autumn application in spring it is advisable to carry out deep loosening with plows or share stubble cultivators with removed moldboards or chisel cultivators.

Deep spring re-plowing is undesirable, since stubble residues buried in autumn, weed seeds and pathogens may be brought to the surface. In years with spring drought on fields infested with root-suckering weeds, deep loosening with share stubble cultivators without moldboards, no-moldboard plows, and ripper cultivators is used.

On strongly compacted, heavy sod-podzolic soils, instead of the first cultivation, the soil is re-plowed, especially for root and tuber crops requiring a deeper loose layer, with simultaneous harrowing. If there is no need for re-plowing with turning of the layer, especially in conditions of a dry spring, no-moldboard deep loosening is used.

In cases when sowing spring crops is carried out after spring plowing, that is, in the absence of autumn tillage, one must not be late with the first spring loosening. The soil is treated as early as possible; otherwise pre-plowing stubble cultivation is done. Tillage depth should be less than with autumn tillage.

The use of fallow cultivators does not provide good and uniform loosening by depth. For pre-sowing treatment it is better to use sugar beet cultivators, for example, USMK-5.4A, equipped with one-sided blades and flat-cutting goosefoot shares, as well as devices for applying herbicides. In dry weather, pre-sowing rolling is additionally done.

For late-sown spring crops, pre-sowing treatment includes cover harrowing and two-three cultivations with simultaneous harrowing, and in dry weather it is supplemented by rolling. With a ridged field surface after harrowing, the soil is leveled with drags or levelers. The depth of the first cultivation is increased to 10-12 cm.

Simultaneous rolling with ring-spur rollers allows accelerating weed germination and creating a compacted layer in the soil profile preventing moisture evaporation. The second cultivation is done when weed seedlings appear.

On well-structured soils with leveled fall plowland and fields clean of weeds, harrowing of fall plowland and one pre-sowing cultivation with harrowing are sufficient. Excessive soil loosening does not promote weed seed germination.

Cultivation depth should not exceed sowing depth. Optimal is placement of seeds on compacted soil, covered from above with loose soil. In this case good aeration and water inflow from below from moist layers are ensured. Sowing into deeply loosened soil is undesirable because when it settles, plant roots may be damaged, and the tillering node of cereals may end up on the soil surface.

Combining pre-sowing cultivation with sowing in one unit allows reducing the number of machinery passes over the field, reducing soil compaction and increasing productivity. Modern powerful tractors allow simultaneously hitching a cultivator and seeder or using combined tillage-sowing units, for example, KA-7.2, including a rotary tiller and seeder; AKPP-3.6 cultivator-seeder; SAC-7.2; SAC-8 or stubble seeders with installed SZS-2.1 shares, etc.

The best quality of loosening, mixing soil with fertilizers and weed destruction is provided by combined tillage units such as RVK-3.6, KFG-3.6, PAV-6, etc.

It is possible to reduce the number of pre-sowing treatments through strip loosening of the soil in the row zone where seeds of row crops are placed, and treating the rest of the field with herbicides. This allows reducing work completion time and energy costs.

Soil Preparation for Catch Crops

For soil tillage for catch crops, a limited period remains, so the main tasks of tillage are to prevent soil drying, loosen it well and level it.

Soil preparation for winter and wintering catch crops sown in autumn, for example, winter rye, winter vetch, perko hybrid, does not differ from tillage when cultivating these crops for grain, taking into account the predecessor, soil type and moisture, and weed infestation. When sowing winter crops after row crops, plowing is replaced by shallow tillage: 1-2-fold disking to 8-10 cm followed by cultivation with harrowing. Pre-sowing treatment for winter rapeseed, winter crambe and other small-seeded crops should also include leveling and rolling of the soil, for which RVK-3.6, RVK-5.4, VIP-5.6, etc. are used.

When placing catch crops after winter and spring cereals, share stubble cultivation to 14-16 cm with simultaneous harrowing, in dry weather with rolling, is done. On heavy soils and weedy fields, shallow plowing to a depth of 16-17 cm with plows equipped with soil-leveling devices such as FMCR-2.3, FMCR-3.5 or treatment with plowing units PKA-2A, combining a plow, rail drag, sections of ring-spur rollers, is done.

On fields weakly infested with perennial weeds, rotary tillage to 8-10 cm is effective, for which rotary tillers and rotary cultivators such as KFG-3.6 are used. Rotary tillage allows loosening the soil, mixing it with fertilizers and preparing for sowing in one pass of the unit without preliminary plowing. In wet years rotary tillage is not effective due to strong sealing of the upper soil layer.

Due to the limited growing period, which is especially important for post-cutting and post-harvest crops, no gap is allowed between harvest of the predecessor, soil preparation and sowing. To reduce the time of soil preparation and sowing, pre-sowing treatment and sowing are combined, for example, winter crops using tillage and sowing units such as KA-3.6, KA-7.2 (rotary tiller-seeder), AKPP-3.6 (cultivator-seeder). Combining tillage and sowing allows reducing the number of machinery passes over the field, the time of soil preparation and sowing, and improving work quality.

In arid conditions, moldboard operations in the soil tillage system for spring crops are ineffective due to large moisture losses by evaporation, so flat-cutting tillage is done leaving plant residues on the field surface. After stubble predecessors, use of a combined unit such as AKP-2.5, which combines surface soil loosening, flat-cutting tillage and rolling, is effective.

One of the main conditions for obtaining high yields of catch crops is thorough preliminary soil preparation. For uniform seed placement and creation of a seedbed before sowing, soil loosening and leveling are done. For this, fallow cultivators KPZ-9.7, levelers VPN-5.6, VP-8 and ring-tooth rollers KZK-10 can be used.

Tillage and sowing of maize, annual grasses after winter crops can be combined in one unit equipped with direct seeding seeders SPP-4, SZS-2.1 and others without preliminary treatment.

In irrigated agriculture, the soil compacts more strongly, so the loosening depth is increased to 18-20 cm, using both moldboard and no-moldboard methods, combining them with surface loosening to seed sowing depth and rolling.

Preceding crops largely determine methods of soil preparation. After harvesting row crops, for example, fodder cabbage, turnip, cultivation and harrowing of the field are sufficient. Strongly compacted soil by the time of sowing repeated crops is disked and harrowed. Heavy clayey soils are plowed, which gives better results than disking. After plowing, the field is also disked, harrowed and rolled.

Tillage of Newly Developed Lands

The task of tillage of abandoned and virgin lands includes creating a loose arable layer and conditions for sod decomposition, accumulation of sufficient available nutrients and moisture, and destruction of weeds.

In forest-steppe and steppe zones, abandoned or virgin lands are broken with a moldboard plow with skimmers in spring or early summer for sowing the next year.

With late plowing in a colder period, the amount of nutrients decreases due to weak microbiological activity and the soil water regime worsens. Plowing is done to a depth of not less than 25 cm. With shallow plowing, sod crumbles poorly and is poorly incorporated, requiring additional surface treatments.

With a small humus layer, plowing is done to its full depth with a subsoiler. With strong sodding before plowing, disking in two directions to 6-8 cm is done; abandoned lands infested with couch grass (Elytrigia repens) and ramose wheatgrass (Leymus ramosus) to a depth of 10-12 cm. After plowing, the soil is rolled with heavy rollers with simultaneous light harrowing. To level the surface, disking along or diagonally to the plowing direction is done. During summer, cultivations or diskings and harrowing are done to destroy the soil crust. With such treatment, intensive decomposition of organic matter, accumulation of mineral nutrients, moisture conservation and weed control are achieved.

When treating bog and floodplain soils, powerful plows, rotary tillers and heavy disk harrows are used. Plowing is done with special brushland-marsh or ordinary plows without skimmers, with a helical moldboard, well turning the soil.

In the case of a high groundwater level, deep loosening is done before plowing, which also promotes faster sod decomposition due to better aeration. Soils with weak sod are treated with heavy disk harrows. The optimal plowing date for sowing in spring next year is summer; in the south, early autumn. After 2-3 weeks disking is performed. A very loose layer is rolled.

Areas covered with hummocks are preliminarily treated with a rotary tiller, then plowed with a moldboard plow with skimmers. Floodplain lands are plowed with a moldboard plow with skimmers. With a thin humus horizon, disking followed by deep no-moldboard loosening is done. Plowing dates are determined depending on texture and soil moisture. With excessive soil moisture, it is preliminarily treated with mole plows or deeply loosened.

Lands from under forest, with thin sod and weak forest litter, are disked in combination with deep no-moldboard loosening. With thick sod and forest litter, deep plowing is done. After removal of shrubs and stumps, plots are treated with a land-clearing harrow, and then the soil is disked and plowed with a brushland plow.

When developing low-productivity upland lands, depending on the humus layer thickness and degree of podzolization, the soil is plowed with a moldboard plow with or without skimmers, or disking with simultaneous deep no-moldboard loosening is done.

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.