Soil greening made easy

Source: landwirt.com

The cultivation of cover crops has established itself in practice as an important component of crop production. However, not every cover crop is suitable for every crop rotation. Based on current knowledge, the active establishment of cover crops in ÖPUL 2015 will be largely similar to the previous measure. A significant innovation, however, will be that these measures will largely only allow cover mixtures. The number of required mixture partners depends on the specific variant. To ensure the advantages of multiple cover crops can be utilized, the cultivation of cover mixtures is already standard practice for many farmers. Site requirements, soil cover, root penetration, and erosion control are important decision criteria when selecting plants.

Safe field emergence

Since individual crops differ in their seedbed and water requirements, the use of mixtures can increase field emergence reliability. Cruciferous plants, such as mustard and oil radish, are advantageous in this regard, as they germinate well even in coarser seedbeds. Buckwheat and mung bean (black seed, ramtill) are also fast-germinating mixture partners. Small-seeded legumes and the dark-germinating phacelia have higher requirements in this regard.

Long ground cover

To effectively suppress volunteer crops and weeds, the cover crop must be able to cover the soil completely and for as long as possible. Leafy crops such as mustard, oil radish, peas, vetch, or sweet pea provide good soil coverage. Phacelia takes a little longer to achieve this, but over time, it also provides good soil cover.

An important characteristic is frost resistance. While buckwheat and mung bean freeze quickly in the fall and thus no longer provide ground cover, cruciferous plants and legumes offer better and longer coverage. Phacelia tolerates temperatures down to minus ten degrees Celsius and covers the ground well into winter, as this year has clearly demonstrated. For a successful cover crop with phacelia, it is crucial that the crop reaches a height of at least 30–40 cm to ensure it is safe from frost damage. To ensure this development, planting must not be too late (at the latest by the end of August).

Hardy crops such as winter vetch, winter rapeseed, or green-cut rye still produce varying plant masses in the fall depending on when they were planted. However, the majority of plant growth will occur in the spring. For some farms, this growth is a welcome addition to the feed base.

Good root

Just as important as the aboveground mass for the formation of a stable soil structure is root development, and this can vary significantly between cover crops. Crops with pronounced, deep taproots (mustard, oil radish) and those with a shallower but finer root system (phacelia, Alexandrian clover, Persian clover, grasses) are available. Large-seeded legumes have a dense, medium-deep root system that leaves the soil very well structured. Nitrogen fixation can also be expected with early planting. If field beans are used in a mixture, it should be noted that they must be planted deeper. Since very few farms have the opportunity to ensure two different seeding depths in one operation, it is advisable to spread the field beans with a fertilizer spreader and then sow the remaining (fine) seeds using conventional soil cultivation and seeding techniques.

Valuable contribution to crop rotation

When selecting suitable cover crops, the entire crop rotation must be considered. In sugar beet crop rotations, beet cyst nematodes can be controlled with resistant mustard and oil radish varieties, but only with early and dense planting. Concerns exist regarding phacelia in such crop rotations, particularly under wet conditions, as it may promote Rhizoctonia. Phacelia can be easily integrated into all other crop rotations commonly used in our country. Rapeseed-intensive farms, on the other hand, should not choose an excessive proportion of cruciferous plants in the cover crop. Farms with a high legume content in the crop rotation should also reconsider using too high a proportion of legumes as cover crops.

Important erosion protection

By adding organic matter, the resulting mulch layer serves as erosion protection. To achieve this, sufficient soil cover is essential even after sowing. Especially in row crops on slopes, the selection of cover crops should also be assessed based on the quality of soil cover after tillage and sowing. Approximately 30% soil cover is necessary to reduce erosion by half. The technical features of seed drills now make it possible to achieve precise seeding even with larger amounts of mulch.

Large-grained legumes and cruciferous plants usually provide sufficiently stable mulch material that continues to offer good erosion protection even after tillage. In this context, cress is becoming increasingly important, as it leaves behind a smaller but very stable plant mass in the spring.

Site-adapted cultivation

A comprehensive cover crop, which is intended to suppress weeds and volunteer crops and provide protection against erosion and leaching, must be planted early enough. Depending on the farm situation and climatic conditions, the most suitable time for this will be the first half of August, but no later than the end of August. In principle, planting should take place as early as possible. However, under conditions of low rainfall in the autumn and a lack of winter moisture, there is concern that the cover crop will consume too much water, which the subsequent crop may lack. With possible planting dates in late July/early August, legumes in particular can develop their full potential, whereas when planted at the end of August or into September, only mustard and oil radish, or possibly phacelia, can establish suitable cover crops.

You can find all products related to soil cultivation here: Soil cultivation!