Techniques of Surface and Shallow Tillage
Shallow tillage — tillage to a depth from 8–10 to 16–18 cm.
Surface tillage — tillage to a depth up to 8–10 cm.
The techniques of surface and shallow tillage include:
- stubble cultivation;
- cultivation;
- hilling;
- harrowing;
- rolling;
- sleaving;
- floating and others.
Surface and shallow tillage allow preparing soil for sowing, caring for fallow and plants, destroying weeds, and creating conditions for tillage at increased speeds and high-quality harvesting.
Stubble cultivation
Importance
Stubble cultivation — a tillage technique that provides loosening, mixing, partial turning and cutting of weeds.
Stubble cultivation makes it possible to incorporate part of the stubble and weed seeds, which in moist soil produce sprouts and seedlings that are destroyed during subsequent tillage. For example, seeds of amaranth (Amaranthus sp.), foxtail (Setaria sp.), barnyardgrass (Echinochloa sp.) and other post-harvest weeds collected before stubble cultivation and placed for germination did not produce seedlings under laboratory conditions, whereas those collected after stubble cultivation with disc implements germinated by 67–92% (NIIISKh of the South-East). Stubble cultivation makes it possible to destroy low-growing weeds found in cereal crops.
Stubble cultivation partially destroys pests and pathogens living on stubble. During stubble cultivation, a loose, mulching soil layer is created on the field surface, reducing moisture evaporation. Stubble cultivation of dried-out compacted soil after harvesting cereal crops creates more favorable conditions for subsequent ploughing, reducing the specific soil resistance during ploughing by 25–34% and preventing further drying out.
A distinction is made between stubble cultivation, performed after harvesting cereals, grain legumes and other solid-sown crops, and soil stubble cultivation.
Technological features
The depth and timing, as well as the stubble cultivation implements, are selected depending on the particle-size distribution, density and moisture of the soil, species composition of weeds, degree of infestation, and preceding crop.
For stubble cultivation, moldboard and disc stubble cultivators are used. Moldboard (share or body) stubble cultivators are lightweight ploughs with small bodies without skimmers, allowing loosening to a depth of up to 18 cm with soil turning. Such treatment is especially effective for cutting root-sprouting weeds. Examples of stubble cultivators: LDG-5A, LDG-10A, LDG-15A. On heavy soils, heavy disc harrows such as BDT-3, BDT-7, BDT-10 are used.
In moist regions with predominance of annual weeds, the stubble cultivation depth is 4–6 cm; in arid regions, up to 6–8 cm. When stubble height is more than 15 cm due to lodging of crops, the depth is increased to 10–12 cm.
When infested with rhizomatous weeds, stubble cultivation is carried out with disc cultivators immediately after harvesting to the depth of rhizome occurrence along and across the field: first pass to 6–8 cm, second to 8–12 cm. The second stubble cultivation is performed during mass regrowth of weeds. Chopping rhizomes of perennial weeds stimulates their germination and depletion of nutrient reserves. When young shoots (awl shoots) appear, usually after 10–15 days, rhizome segments and shoots are ploughed in with ploughs with skimmers to the depth of the arable layer. This technique allows reducing infestation by perennial weeds by 70–75%. Failure to follow this technology or delay in carrying it out can increase field infestation, especially couch grass (Elytrigia repens).
On heavy, compacted and dried-out soils, disc stubble cultivators do not penetrate well and do not completely cut deep-lying rhizomes of weeds. Therefore, the first stubble cultivation is carried out with share stubble cultivators of the PPL-5-25, PPL-10-25 type to a depth of 12–16 cm to bring rhizomes to the surface, or it is replaced by shallow ploughing. Secondary stubble cultivation is carried out with disc implements, which chop rhizomes well enough. Heavy disc harrows can be used for these purposes. After weeds regrow, ploughing is carried out.
For stubble cultivation of soil infested with rhizomatous and root-sprouting weeds, when breaking up the sod of perennial grasses and improving natural forage lands, heavy disc harrows with cutaway bladed discs are used, for example BDT-3, BDT-7, BDT-10, and share stubble cultivators. Stubble cultivation of the sod of perennial grasses and forage lands with heavy stubble cultivators is called discing. On waterlogged soils, discing replaces autumn ploughing.
For better loosening and penetration of working parts, the treatment depth is increased with additional weights or by setting the angle of attack up to 30–35°, which allows good cutting and crumbling of layers, incorporation of plant residues and weed seeds. Better treatment quality is achieved when the directions of stubble cultivation and ploughing coincide. Stubble cultivation of stubble is performed across the direction of movement of harvesting units at a speed of up to 10 km/h.
To reduce soil drying and improve contact of weed seeds with it, stubble cultivation is carried out in a unit with harrows and rollers.
Soil moisture has a significant influence on the effectiveness of stubble cultivation for provoking seed germination. Moisture deficiency delays germination. With sufficient moisture, stubble cultivation ensures germination of 30–40% of weed seeds located at the depth of stubble cultivator treatment.
Timeliness of stubble cultivation significantly affects the effectiveness of this technique. Earlier dates increase the effectiveness of the technique. Delay in stubble cultivation gives post-harvest weeds an opportunity to set seed and replenish the seed bank. The greatest effect of stubble cultivation is achieved when it is carried out simultaneously with harvesting or immediately after it. After harvesting cereals, stubble cultivation is carried out no later than 1–2 days to prevent soil drying. In the Non-Chernozem zone, due to the short post-harvest period, stubble cultivation must be carried out within compressed timeframes.
Zonal features
Stubble cultivation is most effective in regions with a warm, long post-harvest period. In regions of insufficient moisture, the positive effect of stubble cultivation is manifested in years with sufficient precipitation at the end of summer, therefore in these regions early ploughing with ploughs with skimmers without stubble cultivation is more often carried out.
For stubble cultivation of stubble in steppe regions, disc stubble cultivators with flat discs are used; in regions of sufficient moisture, with spherical (concave) discs. In steppe regions with a risk of wind erosion, stubble cultivation is replaced by loosening with needle harrows such as BIG-3A or flat-cutting cultivators KPSH-5, KPSH-9 to a depth of 10–12 cm, which cut perennial weeds while leaving stubble on the field surface. When weeds regrow, the flat-cutting treatment is repeated. Such treatment reduces drying out and allows fairly effective control of weeds.
In zones with a short growing season, for example, the northwest, north and northeast of the European part of Russia, Western and Eastern Siberia, some regions of Kazakhstan and the Trans-Urals, stubble cultivation is not carried out, since weed seeds that have fallen at the end of summer or autumn do not have time to germinate before ploughing or do not produce sprouts at all until warm weather in spring of the following year. After harvesting cereals in these zones, the field is ploughed immediately.
In the southern regions of the forest-steppe and steppe zones with a long warm post-harvest period, stubble cultivation is carried out 2–3 times: first to a depth of 6–7 cm, second to 9 cm, and third to 12 cm with an interval of 2–3 weeks, postponing ploughing to a later date.
In the central, western and southern regions of the Non-Chernozem zone, double stubble cultivation is widely used: the first is carried out with disc stubble cultivators to a depth of 6–8 cm, the second with share stubble cultivators or heavy disc harrows to a depth of 12–14 cm. In combination with ploughing, this method allows reducing infestation by 80–90%, which is especially effective in vegetable growing after early-harvested crops. Stubble cultivation to a depth of 10–12 cm weakens the growth of perennial root-sprouting weeds. After 2–3 weeks after emergence of seedlings, ploughing is carried out to the depth of the arable layer with ploughs with skimmers.
In regions subject to the risk of wind erosion, stubble cultivation is replaced by flat-cutting or other treatment.
Cultivation
Cultivation — a technique of continuous, pre-sowing or inter-row tillage that provides crumbling, loosening, mixing, leveling of the surface and cutting of weeds. As a result of cultivation, a loose layer is created on the soil surface, the water, nutrient and air regimes improve, soil warming in spring accelerates, and microbiological processes are activated.
Continuous cultivation is carried out for pre-sowing soil preparation, in autumn tillage, when caring for clean and coulisse fallows, and in orchards. Pre-sowing cultivation ensures incorporation of mineral fertilizers, ameliorants, herbicides and creates a seedbed. Pre-sowing cultivation is performed to the sowing depth of 4–6 cm or, taking into account soil settlement (especially under irrigation), somewhat deeper. It is carried out across the direction of ploughing, diagonally across the field, or across the direction of preceding treatments.
The cultivation depth is 5–12 cm, more often with simultaneous harrowing.
For pre-sowing treatment and fallow fields, cultivators KPS-4A, KD-6, KSH-3.6A, KSHU-6, etc. are used.
The working parts of cultivators — shanks — are of various designs:
- flat-cutting (undercutting);
- loosening (chisel-shaped and spring-mounted);
- needle discs;
- rod and others.
Undercutting shanks have the form of a flat triangle (sweep shanks) or a knife placed horizontally or at an angle to the cultivator frame (single-sided). Sweep shanks cut weeds well and loosen soil to a depth of up to 10–12 cm; knives treat the soil better at a shallow depth.
Shank cultivators mainly treat soft arable land.
Loosening shanks are narrower, chisel-shaped, mounted vertically on the cultivator frame on rigid or spring stands (spring shanks). Loosening shanks intensively loosen the soil but cut weeds less effectively. Spring shanks are used for loosening and combing out rhizomes. Combining single-sided flat-cutting shanks with chisel-shaped loosening shanks allows deep loosening and thorough cutting of weeds.
Loosening of fields occupied by solid-sown crops is also carried out with rotary hoes, whose working parts are needle discs. When they rotate, the needles cut shallowly into the soil, destroy the crust, loosen the surface layer, pull out young weed seedlings without damaging cultivated plants.
In regions of wind erosion, as well as with non-moldboard treatment, anti-erosion flat-cutting cultivators are used, for example KPG-2.2, KPSH-5, KPSH-9 and KPSH-11 with flat-cutting working parts. The soil treatment depth is 8–16 cm while leaving up to 80–90% of stubble and plant residues. They are used for pre-sowing soil preparation for winter crops, care of fallows for non-moldboard treatment to a depth of 10–16 cm in autumn. For flat-cutting treatment of a layer of perennial grasses and fallow treatment, the OPT-3-5 unit is used, which loosens soil to a depth of 10–16 cm and cuts plant roots.
On light soils, the rod cultivator KSH-3.6A is used with a metal rod — a rod — as the working part. It loosens soil without turning, levels the surface, and when rotating in the direction opposite to the wheels, brings to the surface the stubble incorporated by the stands.
Heavy anti-erosion cultivators KPE-3.8 and KTS-10-1 are also used for treating fallows and pre-sowing treatment of heavy dry and dense soils. They are equipped with spring elastic shank stands, which vibrate during operation and loosen compacted soil without clogging with plant residues. To create a ridged surface, square-section rods are installed on these cultivators, which, rotating from the wheel drive at a depth of 4–5 cm, bring incorporated stubble and cut weeds to the surface and level the soil.
Inter-row cultivation is carried out for loosening and cutting weeds in the inter-row spaces of row crops. In potato plantings, hillers are used that mound soil to the plants, which allows additional stems to form. To avoid damage to plants, protective strips of 10–15 cm are left on both sides of the row, and cultivators are equipped with special guards. For inter-row treatments, universal cultivator-feeders are used, for example KRN-4.2, KRN-5.6, KON-2.8, USMK-5.4A, which allow simultaneous application of mineral fertilizers with treatment.
Harrowing
Harrowing — a technique of surface tillage that provides crumbling, loosening and leveling of the surface, creation of a fine-clod structure of the upper part of the arable layer and destruction of weed sprouts and seedlings. The loose soil layer destroys capillaries through which water flows from lower layers, preventing moisture loss.
High-quality loosening can be performed at physical maturity, that is, at moisture of 60–80% of field moisture capacity. Delay in soil loosening sharply reduces treatment quality. Harrowing is used in the system of pre-sowing soil treatment and when caring for crop sowings, fallows, pastures and perennial grasses.
Harrowing is carried out separately or simultaneously with ploughing, cultivation, sowing or other techniques. For example, pre-sowing harrowing is often combined with cultivation and is used for loosening and leveling soil, incorporating fertilizers and preparing a seedbed.
Depending on the type of harrow, they are divided into:
- tooth;
- disc;
- spring;
- mesh;
- needle;
- rotary.
Disc and tooth harrows are used for loosening heavy, strongly compacted soils. Light harrows are used during sowing and care of crops.
Harrowing of autumn ploughed land and bare fallow in early spring ensures loosening and leveling of the field surface. As a result, capillary connections are destroyed in the upper layer, a mulching layer is created that prevents moisture evaporation, and the leveled surface promotes uniform emergence of seedlings and plant development.
During post-sowing and pre-emergence harrowing of winter crops, row crops and perennial grasses, 70–80% of annual weed seedlings are destroyed, the surface soil crust is destroyed, aeration improves and microbiological processes are activated, especially on heavy soils. It is carried out in cereal sowings before the appearance of “awl shoots,” in sugar beet sowings in the phase of the first pair of true leaves, and in maize sowings — before the 3–4 leaf phase.
To avoid damaging seedlings, harrowing is carried out in one pass during daytime with light tooth, medium and mesh harrows, for example BZSS-1, BSO-4A, ZOR-0.7, etc. Heavy tooth harrows treat soil to depths up to 8–10 cm, medium ones up to 4–6 cm, light sowing ones up to 2–3 cm.
The best time for harrowing is the physical maturity of soil at moisture of 60–80% of minimum moisture capacity. It is carried out across the direction of ploughing, sowing rows or diagonally across the field.
In regions at risk of wind erosion, in the soil-protective (flat-cutting) treatment system, needle harrows BIG-3 are used in the active loosening mode or harrow-hoes BMSH-20. For shallow loosening and cutting of sod to improve soil aeration and incorporate fertilizers when caring for meadows and pastures, the mounted meadow harrow BLSH-2.3 and pasture harrow BPSH-3.1 are used.
Rolling
Rolling — a technique of surface tillage that provides compaction, crumbling of clods and partial leveling of the surface. It is carried out for pre-sowing compaction and leveling of the field surface of previously ploughed or loosened soil, for better inflow of soil moisture and evaporation.
When moisture in loose soil decreases below 60–70% of field moisture capacity, intensive diffuse evaporation predominates, which leads to loss of up to 30–40 t of water per 1 ha daily from physical evaporation.
Rolling is also used when the soil before sowing does not have time to settle after ploughing. If this is not done, the tillering node of cereal crops after soil settling may remain on the surface, which has a destructive effect on plant development, especially winter crops.
Rolling is used to destroy ice crust on winter crop sowings and when plants are heaved in early spring. As an independent tillage technique, it is used before and after sowing crops, as well as in combination with other techniques, for example ploughing, cultivation, harrowing, during spring re-ploughing of autumn ploughed land and fallow treatment. More often rolling is performed simultaneously with sowing, for compaction of ploughed peatlands and newly reclaimed lands, as well as before ploughing in green manures.
Pre-sowing rolling reduces excessive looseness of the surface layer, improving its warming and ensuring uniform seed placement depth, especially for small-seeded crops: flax, clover, alfalfa, root crops, etc. Post-sowing rolling in dry weather ensures better contact of crop seeds with the solid phase of soil, increasing capillary inflow of moisture to seeds and accelerating their germination. Thus, cereal seedlings on rolled soil appear 3–4 days earlier compared to non-rolled soil.
Rolling protects soil from wind erosion.
For rolling mineral soils, smooth water-filled rollers, ring, ring-tooth, ring-spur, etc. are used. Smooth water-filled rollers, for example ZKVG-1.4, SKG-2.1, SKG-2.2, compact soil more strongly, therefore, to loosen the surface layer they are aggregated with light harrows. Ring rollers leave a somewhat ridged surface. Ring-tooth rollers, for example KKN-2.8, KZK-10, level the soil surface well and compact it to a depth of 7 cm with simultaneous loosening to a depth of 4 cm. They are used for pre-sowing rolling, and individual sections — in combination with cultivators, beet and grain seeders. Ring-spur rollers give the best results; after them no additional treatment is required, and a loose mulching layer is left on the surface. To destroy soil crust in sowings, mounted harrow rollers KBN-3 are used.
Rollers are used in units with stubble cultivators, cultivators and sowing tillage complexes PPK-7.2, PPK-8, etc.
Sleaving
Sleaving — a technique of surface tillage that provides loosening and leveling of the field surface. It is carried out with drag harrows consisting of a knife for cutting ridges, rakes for loosening and a drag made of metal angles connected to each other for leveling the soil surface. Sleaving is performed in spring for pre-sowing leveling of ploughed soil, spring harrowing of autumn ploughed land for closing moisture, leveling soil after cultivation, for caring for clean fallows in the summer-autumn period and under irrigation conditions. On well-structured soils, sleaving replaces harrowing. It is more often used before sowing small-seeded crops — flax, sugar beet, vegetables and other crops.
Sleaving is carried out with drags, drag harrows of the SHB-2.5 type.
For leveling and slight soil compaction before sowing or irrigation, a float is used. The float is an iron-bound board or beam about 20 cm wide and about 10 cm thick. When moving, it shifts ridges and clods, partially crushing them, and fills depressions on the surface. The float-leveler MV-6.0A and levelers P-2.8A, DZ-603A, PPA-3.0 are used.
References
- Bazdyrev G. I., Loshakov V. G., Puponin A. I. et al. (2000). Agriculture. Textbook for universities. Moscow: Kolos Publishing House.
- Evtefeev Yu. V., Kazantsev G. M. (2013). Fundamentals of Agronomy: textbook. Moscow: FORUM.
- Niklyaev V. S. (2000). Fundamentals of Agricultural Production Technology. Agriculture and Crop Production. Moscow: Bylina.
