@masterthesis{Brender, type = {Bachelor Thesis}, author = {Brender, Nadja}, title = {Effects of Simulated Drought on Microbial Activity in Biologically and Conventionally managed Soils}, school = {Hochschule Rhein-Waal}, abstract = {Increasing droughts and intensified agricultural management cause stress and disturbance on agricultural soil, but their effects on soil microbial activity are not fully known yet. This thesis studied the effects of induced short-term drought in two contrasting agricultural management systems, namely biodynamic (BioDyn) and conventional (ConMin), on microbial activity. The soil samples taken from the DOK long-term trial were analysed using MicroResp™, fluorometric enzyme assays and disease suppression bioassays. Soil basal- and multiple substrate-induced respiration (MSIR), microbial functional diversity, extracellular enzymatic activity (EEA) and soil suppressiveness against Pythium ultimum (Pu) were evaluated as indicators for microbial activity. Drought increased basal respiration but had no effects on other parameters. Conventional farming decreased EEA involved in carbon (C)- and nitrogen (N)-cycling, while it increased phosphorus (P)-cycling. No significant effects on the interaction between farming system and drought were found. The results indicate that organic farming has, to some extent, positive effects on microbial activity while drought does not decrease activity but induces stress in microorganisms.}, language = {en} }