Functional microbial diversity responses to biodynamic management in Burgundian vineyard soils

ABSTRACT An on-vineyard approach was used to investigate the effects of biodynamic (BD) preparations on soil microbial biomass and microbial functional diversity in five vineyards on calcareous bedrocks under organic management. The vineyards formed two groups according to soil type; Cambic Leptosols (A1, A2, and B) and Calcaric Leptosols (C1, C2) as well as two groups according to duration of BD application; 16 years (A1 and A2) and 1–3 years (B, C1, and C2). The two Calcaric Leptosols contained on average 65% more microbial biomass C, 110% more microbial biomass N, 70% more ergosterol and exhibited a 45% higher basal respiration rate than the three Cambic Leptosols. The vineyards had, on average, 11% lower MB-C:N ratios in the treatments with the BD addition (BD+) than in those without (BD-). Most substrates induced the highest respiratory responses at vineyards A1 and A2 and the lowest at vineyard C2. Averaging the 17 substrates of the multi-substrate-induced respiration (MSIR) approach, the mean respiratory response was approximately 20% lower in the BD+ treatment at vineyard A1 in comparison with the BD- treatment, but 33% higher at vineyard C2. The differences between the BD treatments in the induced respiration rate for individual substrates were significant for 12 substrates at vineyard A1 and for 5 substrates at vineyard C2. The lower the respiratory response, the higher was the anabolic demand for a specific MSIR substrate. More vineyards should be analysed to differentiate between the effects of soil type and duration of BD application.