Influence of precision farming on the microbial community structure and functions in nitrogen turnover

In this paper the effects of precision farming were compared to conventional agricultural management estimating bacterial and fungal diversity and also microbial processes in the nitrogen cycle during the vegetation period of maize. The aim was to find parameters which can be used as indicators for sustainable soil quality. Two plots, a high yield and a low yield site, were selected in the two systems. It could be demonstrated that the microbial biomass and community structure of bacteria and fungi in the top soils were not influenced by precision farming. Microbial biomass was reduced during the summer month, due to the dryness and hot temperatures. The microbial community structure changed in late spring time probably due to the application of fertilizers and high amounts of root exudates in the rhizosphere. The measured enzymatic activities however did not show only a seasonal variation with the highest measured values in spring and early summer, but also clear effects based on the investigated plot (high yield or low yield) and the used farming management system (conventional or precision). Proteolytic activity was significantly higher on the high yield plots at all measured times. Mainly on the low yield sites precision farming caused a higher proteolytic activity compared to the conventional management. Nitrification and denitrification activities were mainly effected after the application of N-fertilizer. Significant higher values were found on the low yield plots, where conventional farming was applied. The results indicate that the effectiveness of nitrogen turnover might be a good indicator for sustainable agriculture and soil quality. (C) 2003 Elsevier Science B.V. All rights reserved.