Crop rotations – what is good with which and what does the soil say?

Crop rotation is not a mystery, but actually just the chronological sequence of crops grown on one and the same agricultural area. The more diverse this crop rotation is, the more varied the agricultural landscape will be. However, it is important to adhere to certain rules so that the crop rotation ultimately leads to the desired agronomic and economic success. This is the only way to ensure that the soil and plants remain healthy and produce adequate yields for farmers in the long term.

Aims of varied crop rotations

• Prevention of disease and pest infestation by biological means
• Maintaining the health of plant stocks
• Regulation of weed pressure
• Maximum utilisation of the vegetation period
• Reduction of N losses
• Use preceding crop effect and crop rotation effect for soil improvement
• Sustainable improvement of soil fertility

Whether one crop fits in before another depends on many factors. For example, for some plant species it is important how the previous crop leaves the soil: well rooted, with a lot of plant residues – or rather the opposite? Furthermore, it can be decisive whether the previous crop required rather many or few nutrients from the soil supply and whether it left any organic substances in the soil to which the following crop may react.

Crop rotations and humus build-up

When planning crop rotation, it is important to also integrate crops that contribute to humus build-up. Crops that build up humus are those that leave more plant biomass on the field than is broken down by the microorganisms in the soil at the same time. Such crops are, for example, clover grass, field beans or catch crops. Crops such as sugar beet, potatoes or fodder maize, on the other hand, are considered humus-depleting: when they are cultivated, more organic matter is broken down in the soil than is brought in by plant residues.

Intercrops enhance crop rotations

Intercrops such as yellow mustard, oil radish, phacelia, clover – or mixtures of these – are becoming increasingly important for crop rotation planning in today’s arable farming and are cultivated in the breaks between the main crops. A special feature of catch crops is that they serve the sole purpose of green manure. As a rule, catch crops are not harvested, but are worked into the soil – complete with stem, leaves and root. In this way, they enrich the soil with organic matter and promote soil fertility. Intercrops also offer other advantages: they cover the soil during the otherwise vegetation-free periods and thus protect it from erosion and drying out. In addition, catch crops absorb nutrients from the soil and thus ensure that they are not lost through seepage or erosion.

Crop rotations as the backbone of arable farming

Crop rotations are not only the backbone of arable farming, but also the basis for the entire farm organisation. Annual crop planning is based on them. They are also the framework for soil cultivation measures, sowing and harvesting dates, fertilisation and plant protection.