Microbial functional diversity indicators in vineyard soils under organic and biodynamic land management

Abstract Background: An on-vineyard approach was used to investigate the effects of biodynamic (BD) preparations on microbial functional diversity and extracellular polymeric substances (EPS) in four vineyards on different bedrocks under organic management. Methods: Soil organic carbon (SOC), total N, microbial biomass carbon (MBC), multi substrate-induced respiration (MSIR), with 17 substrates and H2O, EPS, and glomalin-related soil protein (GRSP) were measured in soils taken from vineyards without (BD-) and with (BD+) biodynamic preparations. Results: The vineyards with BD preparations had improved all soil chemical and biological properties. The MSIR approach was again able to separate clearly BD+ and BD-, confirming previous studies. The glomalin-related soil protein (GRSP) was negatively related to the microbial respiratory response of all substrates added. Conclusions: Lower ratios of EPS-carbohydrates and particularly EPS-protein indicate that soil microorganisms have to divert less substrate to the formation of EPS, so that more of a substrate can be used for the production of microbial biomass.