INFLUENCE OF CROPPING SYSTEM AND NITROGEN INPUT ON SOIL FAUNA AND MICROORGANISMS IN A SWEDISH ARABLE SOIL

The development of a number of components was analysed in an agro-ecosystem study with four cropping regimens, barley without and with N fertilization, grass ley, and lucerne. A great variation in N inputs (1-39 g N m-2 year-1) and cropping systems produced a variation in primary production (260-790 g C m-2 year-1) and input of organic material to the soil (150-270 g C m-2 year-1). This was reflected in variations of total soil animal biomass (1.6-5.1 g C m-2) and in variations in the abundance of various animal groups, nematodes (5.6-9.8×106m-2), micro- (2.6-4.8×10-4 m-2), and macroarthropods (0.9-4.2×103 m-2). In contrast, total bacteria, fungi, flagellates, and amoebae varied quite independently of the organic matter input. Mineralization processes covaried more with C and N inputs and total animal biomass than with microbial biomass. it is suggested that the rather constant microbial biomass was a result of an adjustment in the grazing pressure of microbial-feeding animals to the level of microbial production. © 1990 Springer-Verlag.