Collembola and mites in plots fertilised with different types of green manure

The spring and summer abundance of soil living mites and Collembola was investigated in organically grown field plots which had been covered with either the nitrogen catch crops winter rye, hairy vetch, fodder radish and a control (stubble). The catch crops were incorporated in the soil shortly before sowing of spring barley with undersown clover grass. Microarthropods were extracted from 10 cm deep soil samples and were taken in May, June and August. The densities of both microarthropods were extremely high with up to 120,000 Collembola m(-2) and 90,000 mites m(-2). The highest densities of Collembola were found in the plots with fodder radish as a catch crop, and the most abundant species were Tullbergia sp., Isotoma notabilis and Folsomia fimetaria. The mite fauna consisted mainly of Mesostigmatic and Prostigmatic mites and was more abundant in the catch crop plots than in the control plots in early June. The input of organic matter from the catch crops is supposed to be part of the reason for the high microarthropod densities, but the barley with undersown clover grass may also play a role.