Crop rotation

Crop rotation means changing crops on a specific stretch of land from year to year. For example: one year of pumpkins, then a year of wheat, then a year of grass and clover, and then back to pumpkins. In this way the organic farmer tries to keep the soil healthy and free of diseases and plagues.

Many problems in agriculture are caused by monocultures: large areas of farmland where the same crop is grown year in year out. Harmful insects and diseases often have a preference for a specific kind of plant. Nematodes, for example, like potatoes. If potatoes are cultivated on a certain patch of land, the amount of nematodes will increase every year; in conventional agriculture more and more spraying is required to keep them under control. In a good crop rotation however, other crops are planted, so the nematodes lose their habitat and dissapear. When, after a few year, potatoes return to that stretch of land, the soil is healthy again and fit for potato cultivation.

Of course crop rotation is not just about diseases and plagues, but also about nutrients in the soil and soil structure. Some plants drain the soil, other plants add nitrogen to it. Some plant increase the soils porosity, others make the soil more compact. By rotating the crops in a sophisticated way, the soil remains halthy and fertile.

Actually, this is a special application of the principle of biodiversity. In a biodiverse system, i.e. a large variety of species living in each others proximity, diseases and plagues have less opportunity to increase. The natural balance of ecology makes for a resilient system. In agriculture, however, it is not efficient to grow a mix of crops. Crop rotation is the way to solve this dilemma: in stead of creating variety in space, you create variety over time.