Microbial biomass C (Fig. 5b) showed a similar pattern with highest amounts in the presence of silage and low amounts in
pyrochar-treated pots. While fertilizer level neither influenced the amount of CO2 respired nor the microbial biomass C, presence of plants significantly reduced microbial biomass. In the presence of hydrochar, microbial biomass showed a rather high variance and the effect of the different soils was considerably larger than for the other treatments: There were significantly higher amounts of microbial C in sandy soil compared to calcareous soil. Nevertheless, soil respiration did not differ significantly between the two soils.However, more native soil organic matter was decomposed when microbial biomass was higher