Organic agriculture only allows a few 'natu-

In a field experiment in an organic greenhouse, an innovative cropping system (the so-called 'Köver' system) was tested. In this system, planting beds are divided below ground in two physically separated strips. In one section, vegetables are cultivated at half the normal planting distance. In the other section, the soil is either left fallow or planted with crops antagonistic towards plant-parasitic nematodes. After one growing season, vegetable and fallow strips are reversed. In this way, crop rotation is broadened, with the aim of improving soil health. Compared to the normal cultivation system, the availability of space and light in the Köver system might be unfavourable for some crops (e.g., sweet pepper), which may lead to an initial production loss. However, improved soil health should ultimately lead to a healthier crop and higher yields. The Köver system was introduced in sweet pepper 'Derby' on rootstock 'Capital'. The aim was to achieve production levels of 88-92% or higher of the maximum production targets on a healthy, previously uncultivated soil, while reducing numbers of plant-parasitic nematodes, particularly Meloidogyne incognita. In the Köver system, the following treatments were compared: (1) Sweet pepper 'Derby' on rootstock 'Capital', (2) fallow, (3) Marigold (Tagetes patula) 'Single Gold' (brand name: Ground Control) and (4) the densely planted rootstock Capsicum annuum 'Snooker'. At the end of the season, the number of Meloidogyne juveniles was significantly reduced by fallow, Tagetes and 'Snooker' treatments, compared with the sweet pepper crop. The 'Snooker' rootstock was less effective in reducing Meloidogyne juveniles than fallow or Tagetes. Numbers of juveniles hatching from eggs increased significantly in the sweet pepper crop compared with other treatments. Due to considerable production loss in the sweet pepper crop, antagonistic plants are not recommended in neighboring strips. The fallow treatment was the most promising in combination with sweet pepper in the Köver system. However, further research is needed to confirm these results.