Soil microbial biomass and enzyme kinetics for the assessment of temporal diversification in agroecosystems

In agroecosystems, temporal diversification creates a sequence of short-lived habitats through time. Crop species as well as the diversity of crops grown in sequence might affect soil biodiversity and nutrient cycling processes. In the present study, we focused on a long-term crop rotation established in 2006 in Lower Saxony, Germany on a Luvisol. Winter wheat (WW) and silage maize (SM) were grown in continuous cultivation as well as in rotations. WW rotations span up to six years (including silage maize, sugar beet, winter rape and/or grain pea). Over two years, microbial biomass carbon (MBC) as well as kinetics (Michaelis-Menten Vmax and Km) of extracellular hydrolytic enzymes (b-glucosidase (BG), N-acetyl-b-glucosaminidase (NAG) and acid phosphomonoesterase (AP)) were measured in topsoil (0-10 cm depth) three times during the growing season. Continuous wheat increased soil microbial parameters compared to continuous maize as indicated by the higher microbial biomass to soil organic c...