Farming systems influence soil bacteria

Soil microorganisms are known to influence nutrient cycling and transformation processes in soil. They are involved in maintaining soil quality and therefore in production of agricultural products of high quality. These communities may respond in a highly sensitive way to different environmental influences. High biodiversity may represent the ability of a soil to maintain functioning under changing environmental influences and has been proposed to be a quality indicator of environmental condition. The influence of different agricultural management systems on soil microbial community structures and their diversity was investigated using the DOK long-term experiment. Molecular genetic methods allowed assessing microbial community structures with high resolution. Application of farmyard manure, crop rotation, and the different farming systems, in this hierarchical ranking order, revealed a significant influence on the composition of the soil bacterial community. In contrast, bacterial diversity remained highly similar in all analyzed systems. Strong differences in microbial community structures do not necessarily include changes in their diversity, confirming the importance of applying such molecular tools. However, further investigations are required to interpret beneficial or detrimental effects on soil quality.