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Minimum tillage

In the conditions of ecological soil-protective farming more economical energy-saving technologies of minimum tillage are widespread.

Minimum tillage is scientifically grounded tillage, which allows to reduce energy and labor costs by reducing the number, depth and cultivated area of the field, combining and performing several technological operations in one working process.

A variety of minimum tillage is no-till, or direct seeding, which implies sowing in uncultivated soil. Herbicides are used to control weeds. Mulching, conservation tillage and other tillage technologies, different in their intensity and depth, combine flat-cutting and chisel tillage with saving of more than 30% of stubble and plant residues on the field surface. Vegetable mulch allows to reduce moisture loss by evaporation, protect soil from overheating and erosion. That is why minimum tillage is referred to soil-protecting.

The importance of minimizing tillage

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

Intensification of arable farming requires increasing tractor capacity, working width of implements, but reducing the weight and pressure on the soil. For example, a tractor К-701, weighing 12 tons, has a wheel system pressure of 1.7-1.8 kg/cm2. Permissible load on the soil in the state of physical ripeness during plowing is 1.0-1.2 kg/cm2. Excessive compaction leads to deterioration of agrophysical properties of the soil, reducing, for example, field germination of winter wheat seeds by 25% and yields by 12-30%.

The use of intensive tillage in crop rotations with the predominance of annual plowing activates the microbiological processes of humus decomposition. Black-earth soils at the mouldboard tillage lose 0.8-1.2% of humus for 30 years, which negatively affects the balance of organic matter and leads to significant losses of nutrients and energy. Accelerated decomposition of humus contributes to the development of erosion processes, especially on sloping lands. For this reason the minimum tillage is considered as the most important condition of keeping the potential and increasing the effective fertility, protecting the soil from erosion by improving the humus balance and reducing losses of nutrients. At the same time it significantly reduces energy costs for processing and the time of field work.

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

  • high technological level of cultivation of crops,
  • qualitative mechanized field works in optimal terms,
  • provision of the farm with effective means of plant protection and fertilizers.

Minimization of tillage is achieved by high technical equipment of the farm with combined tillage and seeding aggregates that combine up to 4-5 technological operations, for example, tillage, application of fertilizers, herbicides, seeding.

Minimum tillage is primarily required on black earth, chestnut, gray forest and well-cultivated sod-podzolic soils with agro-physical properties optimal for plants, fields clean from perennial weeds. For example, reduction of deep tillage on black earth, chestnut, gray forest and other soils is possible if the equilibrium density is approximately equal to the optimum and does not exceed 1.2-1.3 g/cm3 for cereal crops and the air content is at least 13-15% of soil volume.

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

  • humus content,
  • water-retentive structure,
  • porosity coefficient,
  • degree and type of weediness of the field.

Suitable, for example, sod-podzolic soils are considered with a humus content of at least 2%, water-retentive aggregates, that is, particles smaller than 0.25 mm, more than 25-30% and a porosity coefficient of more than 0.9. Soils with porosity coefficient less than 0.9 are unstable and prone to compaction, which negatively affects yields.

The main directions of minimum tillage include:

  • reducing the number and depth of main, pre-sowing and inter-row tillage in crop rotations on highly fertile soils and favorable agrophysical properties, subject to the use (if necessary) of herbicides;
  • replacement of the deep main tillage for some crops of the crop rotation by surface and shallow tillage at the expense of the use of wide-blade flat-cutting, chisel, disk and other tools, especially for winter and spring grain crops;
  • combination of several technological operations and methods in one working process through the use of combined tillage and seeding aggregates;
  • use of direct sowing of cereals, corn without preliminary, strip (in the area of the row) pre-sowing tillage when growing row crops.

The choice of minimum tillage methods depends on fertility level, moisture zone, biological characteristics of the crop and the degree of weeding of the fields. For example, on moist lands of the North-West region of the Non-Black Soil Zone due to soil compaction the autumn plowing for potatoes is replaced by shallow disc tillage to a depth of 10-12 cm.

The use of herbicides reduces the number of inter-row tillage in row crops. On light soils, there is a pre-sowing harrowing for early spring crops, and in the system of main tillage deep plowing is periodically replaced by shallow plowing or discing by 10-12 cm.

Cultivation of potatoes, root crops and vegetable crops on fields without perennial weeds exclude autumn plowing or replace it with discing. This method is effective on light granulometric composition of sod-podzolic soils, dark gray forest and other well-cultivated soils.

A good mixing of soil with fertilizers is achieved in spring pre-sowing milling with the use of tools with active working tools, such as КФГ-3,6, ПР-2,7, which improves the quality of processing and increases yields by 10-20%.

According to the Ryazan State Agricultural Academy, plowing in the first year with the embedding of organic fertilizers is enough for repeated corn cultivation on gray forest soils, in the next three years it is acceptable to replace it by discing to a depth of 10-12 cm.

Minimum tillage is especially effective on the black earth soils of the Central Black Earth zone, the North Caucasus, the Volga region in the cultivation of winter wheat, following the legumes, annual grasses, corn for silage.

Plowing is replaced by shallow loosening to a depth of 10-12 cm using disk and polydisc tillers, flat-cut cultivators such as КПШ-9, КПШ-11, equipped with needle harrows БИГ-3А and ring-spurring rollers.

Minimization of the main tillage is achieved by combining plowing and additional techniques for leveling and compaction of the soil. For this purpose, combined ploughing aggregates are used, such as ПКА-2, including a plough, a rail beam in the form of a bar of angular rolled steel, sections of ring-spur rollers, which well embeds plant residues, turf, levels and compacts the soil. To improve crumbling and leveling of soils at tilling, 5- and 6-hull ploughs are equipped with special devices such as ПВР-2,3 (narrow wedge and ring-shaped discs), and semi-mounted 7- and 9-hull ploughs – ПВР-3,5.

Combined tillage and seeding units, such as the КА-3,6 (milling machine and grain seeder), МКПП-3,6 (cultivator and grain seeder), ПКР-3,6, СЗС-2,1М, СЗС-6, СЗС-12, КФГ-3,6 and others, allow to combine tillage, fertilizing, seeding and rolling of the soil.

The use of aggregates with milling tools allows to refuse from plowing, thus the quality of seedbed preparation improves, labor productivity increases by 1.6-2.2 times, and labor costs decrease by 30-40%. Yield of cereal crops increases by 0.35-0.39 t/ha.

Flat-cutting protects the soil from erosion and reduces energy costs compared with plowing. In areas of wind erosion, sowing aggregates that combine in one pass pre-sowing tillage, row fertilizer application, seeding and rolling are more effective. Also for this purpose, a discer-seeder ЛДС-6 and others are used.

Quality pre-sowing tillage of ploughed soil for sowing cereals, sugar and fodder beets, corn provides the use of combined units, such as PBK-3,6, PBK-5,4, ВИП-5,6. In one pass they carry out crumbling of clumps, surface leveling and soil compaction.

Table. Crop yields depending on the method of technological operations (Puponin, 1984)[1]Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. - M.: Publishing house "Kolos", 2000. - 551 p.

How to perform technological operations
Yield, t/ha
On average over 5 years
winter wheat
barley
vetch-oat mixture (green mass)
Separate (cultivation with harrowing, rolling, seeding)
4.31
3.52
22.5
3.31
Combined (tillage and seeding simultaneously with the КА-3.6)
4.7
3.87
23.1
3.43

For pre-sowing tillage of black earth prone to wind erosion, plowing is replaced by the use of combined aggregates such as АКП-2.5, AKP-5, including disc and flat-cut working tools, needle harrows, ring-spur roller. They are used for soil preparation for winter crops following non-fallow stubble predecessors.

The АПЛ-1,5 and АПЛ-2 aggregates are effective for radical improvement of meadows and pastures, which in one pass apply fertilizers, loosen the soil, cut the turf, sow the grass seeds and roll the soil in rows. Combining these operations accelerates the cultivation of meadows and pastures and increases their productivity with less labor and energy.

Annual surface and flat-cutting cultivation increases the weed infestation of the fields by 25-30%, especially by perennial weeds, and the infestation of crops by diseases and pests. For this reason, the crop rotation alternates moldboard and non-moldboard tillage with the use of effective plant protection agents. Continuous surface and shallow tillage cause a sharp differentiation of the arable layer soils with accumulation of humus and nutrients in the upper 10-cm soil layer.

Reduction of biological activity in the lower layers and mobilization of nitrogen by microorganisms in the upper 10 cm layer worsen nitrogen nutrition of plants. For this reason, doses of nitrogen fertilizers are increased by 10-15% at minimum tillage.

Continuous surface tillage also leads to compaction of the lower soil layers, their water and air permeability deteriorate, which causes the need for periodic deep loosening with the use of non-moldboard or chisel tools.

Sources

Farming. Textbook for universities / G.I. Bazdyrev, V.G. Loshakov, A.I. Puponin et al. – Moscow: Publishing House “Kolos”, 2000. – 551 с.

Fundamentals of agricultural production technology. Farming and crop production. Edited by V.S. Niklyaev. – Moscow: Bylina, 2000. – 555 с.

Fundamentals of Agronomy: Tutorial/Y.V. Evtefeev, G.M. Kazantsev. – M.: FORUM, 2013. – 368 p.: ill.