MICROBIAL COMMUNITY STRUCTURE AND ACTIVITY IN AGRICULTURAL SOILS UNDER DIFFERENT MANAGEMENT

For the development of management strategies in sustainable agricultur e it is necessary to describe and predict the role of soil microbes in different management systems. The classical approach uses the microbi al biomass as the key parameter for the entire system, but for ecologi cal purposes the variability of biotic parameters in time and space ha s to be better described. Moreover, the biomass active in the total so il profile or its most active zones should be used as a basis for the assessment of soil activity. The sum of adenylates was found to be mor e closely related to the microbial biomass than was ATP, which however appeared to be a better indicator for the microbial activity, Fatty a cids from phospholipids were highly correlated with the soil microbial biomass. The pattern of fatty acids from soils under different long-t erm management indicated a high potential to typify the microbial comm unity in soils and special organism populations. To overcome the probl em, that only a small portion of the soil inhabiting microbes can be c ultivated, first steps to use serological and genetical methods to dir ectly identify or localize specific populations in the rhizosphere are shown.