Aggregate stability and visual evaluation of soil structure in biodynamic cultivation of Burgundy vineyard soils

ABSTRACT An on-vineyard approach was used to investigate effects of the biodynamic preparations horn manure and horn silica (BD) on the soil structure in five vineyards on different bedrocks and that had been under organic management for different time periods. The underlying hypothesis was that the effects of the biodynamic preparations increase aggregate stability and improve soil structure. The results showed that soil aggregate stability during wet sieving was not different in the treatment with biodynamic preparations (BD+), compared with that without preparations (BD-). Based on visual evaluation (VESS), improvements in soil structure in the BD+ treatment, compared with BD-, were not significant for macropores/biopores, drop test topsoil or subsoil colour, but significant improvements were observed in drop test subsoil (p = 0.009), topsoil colour (p < 0.000), root penetration (p = 0. 017), structure of surface (stable aggregates, little encrustation, p = 0.006), structure of topsoil (p = 0.030), structure of subsoil (p < 0.000) and the colour change from topsoil to subsoil was at a greater depth (p = 0.049). Based on previously reported results showing significant changes in the microbial activity in soil from the BD+ treatment, using the same soil samples, it was thought possible that the observed differences in soil structure between BD+ and BD- were linked to the differences in the microbial activity.