Influence of cropping system and nitrogen input on soil fauna and microorganisms in a Swedish arable soil

Summary

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.