Peculiarities of mouldboard and non-mouldboard tillage using agricultural implements

tillage 93

The semi-helical mouldboard has a steeper share. The front part of the mouldboard is cylindrical, while the rear part is close to helical. They are installed on:

• brush-bog ploughs for the tillage of drained peat and boggy mineral soils;
• general-purpose ploughs for the tillage of soddy old-arable soils and perennial grasses.

The highest quality of tillage is achieved when it is carried out by ploughs with skim coulters. Ploughing with mouldboard ploughs equipped with skim coulters is called cultural ploughing.

For high-quality ploughing with ploughs equipped with skim coulters, the field must be cleared of straw, plant residues, and weeds to avoid clogging the skim coulters. Often, fields left uncleared after harvesting are the reason for removing the skim coulters.

Fig. 13. Mechanisms for tillage: A — plough with a coulter disc (3), skim coulter (2), share (4), and mouldboard (5); B — T. G. Maltsev's plough for non-inversion tillage with share (4), lifter (6), furrow shield (7), and heel (8); C — chisel ploughs (12) and cultivators (13); D — rotary tiller: shaft (9), blades (10), discs (11); 1 — frames and standards

Non-inversion method is the action of working mechanisms of tillage implements and machines on the soil without changing the arrangement of genetic horizons and without differentiating the tilled layer by soil fertility in a vertical direction, with the aim of loosening or crumbling the soil, cutting underground plant parts, and preserving above-ground plant parts on the soil surface. With this method, part of the stubble and cut weeds are preserved on the soil surface, while pest eggs and larvae are brought to the loosened topsoil.

The non-inversion method of tillage is performed using ploughs with removed mouldboards, non-inversion ploughs, sweep ploughs, chisel ploughs, and cultivators (Fig. 13, B, C).

Tillage with non-inversion ploughs, developed in Russia by T. S. Maltsev, is widely used in the Southern Urals and the Altai. Its essence lies in the fact that on each field, once every 4—5 years, loosening to a depth of 35—40 cm is carried out with a non-inversion plough, and in the period between deep tillage operations, annual surface tillage is performed using disc harrows to a depth of 10—12 cm.

Reducing mouldboard tillage protects the soil from water and wind erosion and preserves soil moisture. Non-inversion tillage also has a number of disadvantages. Weed seeds, part of the stubble along with cut vegetative weeds, and eggs and larvae of pests and pathogens of agricultural crops are not buried at the bottom of the furrow but remain on the soil surface or at a shallow depth.

Sweep tillage is a technique of non-inversion tillage of soil that ensures crumbling, soil loosening, and cutting of underground plant organs to a depth of 27—30 cm using sweep ploughs (deep rippers), while preserving up to 90% of the stubble on the soil surface.

Scientific research and practice show that ploughing is not always the best method of tillage. The system using mouldboard ploughs needs improvement. Chisel ploughs and cultivators are replacing the plough. They contribute to better preservation and accumulation of soil moisture, have a positive effect on physical properties and the biological activity of soil microorganisms, prevent the development of water and wind erosion, and do not leave dead furrows or back furrows.

Chisel tillage is the loosening and crumbling of the tilled and sub-tilled horizons without inversion of the furrow slice. Unlike share and disc tillage machines, a chisel loosens the soil by tearing it from the monolith, without compacting sub-tilled layers and without forming a "plough pan." By cutting slots, it contributes to better water absorption by the soil and its deeper penetration. Depending on the depth of soil loosening, chisel implements are divided into cultivators, ploughs, and deep rippers. Tillage 95 Cultivators loosen the soil to a depth of 25 cm, ploughs to 40 cm, and deep rippers to 60 cm.

"Chisel" in English means a "heavy cultivator" or a "plough for non-inversion soil loosening." Periodic deep loosening with chisel ploughs is used on soils with a compacted sub-tilled horizon, those prone to water erosion, and those with temporary surface excess moisture. On soils prone to water erosion, deep chiseling helps convert surface runoff into sub-surface flow, increasing moisture reserves and reducing soil erosion.

Chisel tillage as a primary tillage method is used in the cultivation of winter crops, intermediate crops after row crops, early spring loosening of autumn-ploughed fields, and the breakdown of perennial grass sod. Chisel loosening of sod-podzolic, poorly cultivated soils with a heavy textural composition should be carried out once every 3 years to a depth of 40—45 cm.

Chisel tillage is becoming increasingly widespread because it is soil-protecting due to the loose and ridged bottom of the tilled layer, is less energy-intensive, and is more productive compared to ploughing. The working width of a chisel cultivator is 5.1 m, while that of a plough is 1.75 m; both implements are pulled by a tractor. It has been shown that using a chisel is approximately three times more efficient.

Rotary tillage: when a rotary tiller replaces a plough

The rotary method is indispensable when it is necessary to quickly eliminate non-uniformity of the tilled layer in terms of structure and soil fertility. The rotating working elements of disc cultivators and rotary tillers intensively crumble the soil, thoroughly mixing it with plant residues and fertilizers. On heavy, compact, and peaty soddy lands, a rotary tiller is capable of completely replacing a plough and preparing the field for sowing in a single tractor pass.

The use of milling in technology allows several operations to be performed simultaneously:

• intensive soil loosening;
• deep crumbling and mixing of layers;
• destruction of sprouts, seeds, and vegetative weeds;
• incorporation of fertilizers, herbicides, and other chemical substances.

When the rotary tiller is operating, the blades on the rotating drum grab the soil and, under the action of centrifugal force, throw it against the protective guard. The degree of pulverization is regulated by the peripheral speed of the drum, the shape of the blades, and the length of their working part. Field, garden, or marsh rotary tillers are used for the work. The latter cope excellently with thick, lumpy sod when improving hayfields and pastures.

Surface tillage techniques and combined schemes

To optimize costs, agronomists often use combined tillage methods. They combine mouldboard, non-mouldboard, and rotary techniques, distributed by soil layers and timing. In this case, the depth of surface tillage performed by discs or harrows does not exceed 15 cm.

• Surface tillage depth limit — 15 cm
• Pressure on a heavy harrow tine — 1.5 kg
• Stubble cultivation with disc implements — 6–12 cm
• Stubble cultivation with share implements — 8–16 cm

Harrowing is used in spring to conserve soil moisture on winter fallow, and for tending to crops of cereals, row crops, grain legumes, and perennial grasses. Tine harrows crumble clods, compact, and level the surface. The working depth depends on the pressure applied to one tine of the implement:

• heavy harrows (pressure 1.5 kg) loosen to 5—8 cm;
• medium harrows (pressure 1–1.5 kg) loosen to 4—6 cm;
• light harrows (pressure 0.5–1 kg) work to a depth of 2—3 cm.

Discing provides crumbling, loosening, partial inversion, and mixing of the soil. The spherical discs of the harrow are set at an angle of attack to the direction of travel: the larger it is, the deeper the tillage goes and the better the weeds are cut. On heavy and soddy soils, implements with notched discs are used, and for work on uneven terrain, chain harrows with independent tine movement are suitable.

After harvesting cereals, stubble cultivation is mandatory. This technique provokes weed germination, destroys pests, and incorporates crop residues. Disc stubble cultivators cut horizontal rhizomes to a depth of 6—12 cm, while share implements ensure a higher-quality furrow slice inversion to a depth of 8—16 cm. Chisel cultivators can also be used for stubble cultivation.

Auxiliary techniques: from cultivation to water balance regulation

To create an optimal water-air regime and combat weed vegetation, agronomists use a wide range of auxiliary techniques. Cultivation allows the top layer of soil to be crumbled and mixed while simultaneously cutting the roots of weeds. In steppe regions and zones with a high risk of wind erosion, standard sweeps are replaced with flat-cutters or rod weeders to preserve stubble on the field surface.

Rolling is performed with smooth, ring-spur, or ring-tine rollers to level the field and break the soil crust. To retain moisture and combat erosion on slopes, more specific techniques are applied. For example, pitting with disc pitters retains meltwater and rainwater, and ridging with ridgers creates temporary drainage furrows.

When caring for row crops, hilling and bunching (thinning) are used. Hilling piles soil up to the base of the stems, stimulating the development of the root system. Bunching is used for the mechanical thinning of beet seedlings. Specially positioned cultivator blades cut out excess plants while simultaneously loosening the inter-row spaces.

Depth matters: classical and specialized ploughing

The choice of tillage depth depends on the soil type, field weediness, and the requirements of the specific crop. Classical mouldboard ploughing provides crumbling and inversion of the furrow slice by at least 135 degrees, restoring the soil fertility of the plough layer. For deep ameliorative tillage, special ploughs and rippers are employed.

Depending on the plough design and the objectives, ploughing is divided into several technological types. This determines the degree of incorporation of crop residues and the surface structure of the field after the implement pass. On light soils, disc cultivators may be used instead of a plough.

• Cultural ploughing — operation of a plough with jointers or corner cutters. The topsoil is dropped to the bottom of the furrow, and the lower layer is placed on top.
• Furrow slice inversion — ploughing with a full 180-degree turn of the soil.
• Furrow slice casting — a 135-degree turn with the slices laid at a 45-degree angle to the horizon.

When it is necessary to deepen the plough layer on sod-podzolic or reclaimed peat soils, ploughing with subsoil mixing is used. In long-cultivated lands, the best results are provided by ploughs with notched bodies. They turn over the top layer while undercutting and loosening the bottom layer without bringing it to the surface at a depth of up to 30–35 cm.

To regulate the water regime of waterlogged or heavy clay soils, special ameliorative practices are used. These include subsoiling, mole drainage, and stepped ploughing across slopes. In the latter case, the even-numbered plough bodies operate at the standard depth, while the odd-numbered ones run 10–15 cm deeper to retain runoff.

• Cultivation depth — 6–12 cm
• Width of slots during subsoiling — 2.5–4 cm
• Subsoiling depth — 30–60 cm
• Mole drainage depth — 35–40 cm
• Diameter of mole drains — 6–8 cm
• Distance between mole drains — 70–140 cm

When developing a tillage system, it is necessary to consider the following factors:

• amount and nature of precipitation and its annual distribution;
• sum of positive temperatures and length of the growing season;
• particle-size distribution of the soil, depth of the plough layer, and humus content;
• degree of soil moisture and erosion susceptibility;
• preceding crop and the time the field becomes available;
• level of weed infestation and the predominant biological group of weeds.

Any tillage system is carried out taking into account the biological features and the order of rotation of crops grown in the crop rotation.

A tillage system is generally compiled with energy efficiency in mind and has a soil-protection focus. Its classification is based on the following criteria:

• biological and technological features of the cultivated crops (spring cereals and grain legumes; row crops; winter crops; catch crops — post-harvest, stubble);
• predecessors (after winter and spring cereals; perennial grasses; row crops; annual grasses in catch crop fallow — green manure fallow; bare fallow);
• susceptibility to erosion and radionuclide contamination (water erosion; wind erosion; radionuclide contamination);
• particle-size distribution and soil type (sandy and loamy sand; light and medium loamy; heavy loamy; peat; waterlogged mineral);
• timing of application (primary; pre-sowing; post-sowing).

This is the first and deepest tillage operation, performed after harvesting the preceding crop in a specific way, either independently or in combination with surface tillage practices to solve the main tillage tasks. It fundamentally improves soil conditions for the life of agricultural crops.

As a result of its implementation, the structure of the plough layer changes, the most favorable conditions for biological, physical-chemical, and physical processes are ensured, and the nutrient cycle is intensified. Due to improved gas exchange and optimization of water and thermal regimes, the activity of soil microflora increases, which enhances the content of plant-available forms of nitrogen, phosphorus, potassium, magnesium, sulfur, iron, and other vital plant nutrient elements.

Primary tillage significantly clears the soil of seed and vegetative reproductive organs of weeds, as well as the pathogens of diseases and pests of agricultural crops. When implemented, fertilizers and plant residues are incorporated into the soil, and conditions are created to protect the soil from erosion processes and the migration of radionuclides into sub-plough soil layers.

Primary tillage is carried out during the summer-autumn period (winter ploughing, for winter crops) or during the spring-summer period in the year of sowing spring crops. When choosing the method and techniques of primary tillage, the biological characteristics and technology of the cultivated crop, the predecessor, soil and climatic conditions, the type of weed infestation, and the soil's susceptibility to erosion are taken into account. Taking these features into account, the timing of primary tillage is also determined.

Primary tillage for winter, post-harvest, and stubble crops is determined by the predecessor and the timing of its harvesting, the granulometric composition, and the degree of soil moisture. The techniques of primary tillage include: ploughing, non-inversion and chisel tillage, and milling.

primary and surface tillage 101

Primary tillage for spring crops is, as a rule, carried out in the summer-autumn period or in the spring. The optimal timing for primary tillage for spring crops is autumn; it has a significant advantage over spring tillage in solving the main tasks of soil tillage. Spring timing for primary tillage for spring crops is prompted by the necessity of applying organic fertilizers (for row crops) or organizational reasons.

Ploughing is the most important tillage technique, which is carried out to create the most favorable conditions in the soil for the growth and development of plants. The main task is the loosening of the plough layer with furrow slice inversion and mixing of particles, with complete incorporation of sod, stubble, other post-harvest plant residues, as well as organic and mineral fertilizers. The better the soil is ploughed—that is, the more complete the inversion of the furrow slice across the entire field and the higher the quality of soil loosening—the better conditions are created for the growth and development of cultivated plants, and therefore the higher the yield of agricultural crops. Various designs and mouldboard shapes of ploughs are used for ploughing.