Can Nitrogen management affect the biological quality of soil?

The main objective of this study was to investigate the effects of different rates and sources of nitrogen on the earthworms and soil microarthropods communities. We compared three different cropping systems that were started the year 2000: - Organic livestock system (N fertilisation based on the use of farmyard manure); - Organic stockless system (N fertilisation based on green manuring of hairy vetch, and on the use of commercial organic nitrogen fertilizers); - Conventional system (N fertilisation based on the use of urea and ammonium nitrate). Soil samples were collected at two depths (0-10 cm, 10-20 cm) in autumn 2006 and spring 2007 therefore six years after the starting of the experiment. In order to characterize the earthworms populations, the number of individuals and of casts as well as the earthworms live weight were measured. We extracted soil microarthropods using the Berlese Tullgren device. We calculated different biodiversity indices (Shannon–Weiner, Simpson, Margalef, Menhinick ) and Biological Quality Soil Index, (Parisi et al, 2005). Results proved that the different nitrogen fertilization management affected significantly the diversity and dominance indices (Shannon–Weiner, Simpson) of microarthropods communities. Agronomic treatments did not influence the earthworms number and abundance or richness of microarthropods taxa.