Technological features of soil preparation and tillage for vegetable crops

Why vegetable crops require special soil preparation

The quality of soil preparation in vegetable growing directly determines the marketable appearance and yield of the produce. Unlike grain crops, most vegetables are extremely sensitive to field leveling and the structure of the plough layer. Proper tillage does not just improve moisture availability, but also activates cellulose-decomposing and nitrogen-fixing microorganisms.

The specifics of field preparation for vegetables are determined by three key biological factors. Each of them directly influences the choice of agricultural practices. Accounting for these nuances helps to avoid sparse emergence and harvest losses.

• Small seed size. To obtain uniform emergence, the topsoil must have a fine-cloddy structure and an impeccably smooth surface.
• Slow germination. Seeds of celery, carrot, coriander, and parsley contain essential oils, while onion and sea kale have a dense seed coat. They need plenty of moisture for swelling, so it is important to complete primary tillage in the fall to accumulate and preserve winter-spring moisture reserves.
• Formation of the harvest in the ground. Root crops, rhizomatous and tuberous plants are sensitive to soil density. To obtain uniform marketable produce, agronomists often use ridging, bed forming, and irrigation furrows, which improve conditions for root growth.

• Ploughing depth for vegetable crops — 25–30 cm
• Soil turnover angle by plough — at least 135°
• Stubble breaking depth for creeping-rooted weeds — 14–15 cm
• Stubble breaking depth after perennial grasses — up to 12 cm

Technology of primary soil tillage for winter fallow

Primary tillage begins immediately after harvesting the predecessor using the semi-fallow system. Crop residues are pre-shredded with machines like KIR-1.5 or disc harrows. This facilitates subsequent ploughing and accelerates the mineralization of organic matter.

If the field is heavily infested with creeping-rooted weeds, preparation follows this scheme:

1. Shredding of predecessor crop residues.
2. Stubble breaking with disc ploughs to a depth of 14–15 cm.
3. Repeat stubble breaking after weed regrowth (if necessary).

On light soils, ploughing to 27–30 cm is carried out as soon as weeds begin to regrow. During a prolonged warm autumn, the ploughed field is additionally cultivated or treated with disc harrows. Before winter, it is leveled with long-base land levelers and deeply loosened with a chisel cultivator. In some farms, ridges or beds are formed in such fields in the fall so that the soil dries out faster in the spring, allowing for earlier sowing.

When preparing a plot after perennial grasses, the technology changes. Regardless of soil moisture, after the last mowing, deep stubble breaking is carried out with flat cutters or disc ploughs to a depth of up to 12 cm to cut off the grass growth points. If they begin to regrow, a second stubble breaking is performed. The cycle concludes with deep winter ploughing in late autumn.

Deep ploughing to 25–30 cm is performed with standard ploughs (PLN-4-35, PL-5-35) or reversible implements (JD 975, JD 995, PO-3, PO-4). This technique regulates the air, water, and thermal regimes of the soil, as well as destroying pests and disease pathogens. Reversible ploughs are preferable as they allow ploughing without the formation of ridges and dead furrows.

Ploughing depth is selected based on the soil-climatic zone, type, and depth of the plough layer. The agronomist must also take into account the biological characteristics of the vegetable crops, the depth of tillage for predecessors, and weed infestation. Depending on these factors, tillage is divided into four main types.

The quality of the tractor operator's work in the field is assessed by several critical parameters. The ploughed land must be continuous and leveled, without skips or incomplete soil turnover. It is important to maintain the specified depth, observe the straightness of the ridge and dead furrow, and meet optimal agrotechnical deadlines.

Soil turnover must be complete, and the layer itself must be loose. Post-harvest residues, weeds, and fertilizers should be buried by at least 95%. Cloddiness of the ploughed land is strictly regulated: soil clods larger than 10 cm may account for no more than 15% of the total soil volume.

Soil preparation for winter and early spring sowing

Usually, after autumn ploughing, the field enters winter with a ridged surface and does not require additional machinery passes. However, in vegetable growing, winter planting of garlic and onions, as well as ultra-early spring sowing of carrots, require a different approach. The field surface must be perfectly levelled and loosened from the autumn so that it is possible to enter the field in the shortest possible time in the spring.

Plots that are cleared of predecessors early are allocated for such sowings. They are tilled using a semi-fallow method — this allows for maximum weed control and moisture conservation. The number of surface tillage operations is adjusted depending on weather conditions.

1. Perform ploughing at the optimal time — from late August to early September.
2. Use harrows simultaneously with the plough to level the surface immediately.
3. Periodically cultivate the field until cold weather sets in to destroy weeds and maintain soil structure.

• Incorporation of crop residues — at least 95 %
• Share of large clods (over 10 cm) — no more than 15 %
• Planting of garlic, shallots, and seed crops — October
• Winter sowing of carrots and bulb onions — late November – early December

The described technology of autumn tillage is focused on southern chernozems. On other soil types, the composition of operations before and after ploughing may vary depending on the density and soil moisture. At the same time, the general principle of the sequence of tillage operations remains unchanged.