- Corn silage, consisting mainly of lignocellulose material with a wide C-to-N-ratio, favours microbes independent of fertilizer level and probably causes an immobilisation of N, while plants take up only small amounts of NO3
fertilizer and remain rather small showing signs of nutrient deficiency. Corn silage is readily available for microbial decomposition, as shown by d13C values of microbial respiration.
- Hydrochar, characterized by a narrow C-to-N-ratio and spherically arranged aromatic structures, causes mixed effects: While plants are well nourished with N mainly originating from the decomposition of the soil amendment, microbial biomass and respiration are also high and large amounts of the added material are released as CO2 by microbes, which effectively mineralize the hydrochar.
- Plants grown with pyrochar (wide C-to-N-ratio, highly aromatic structure) effectively use the added fertilizer N and compete successfully against microbes, which only reach a relatively small biomass and respire significantly less C compared to the two other treatments. Additionally, a much smaller percentage of the respired CO2 originates from pyrochar.Our results thus confirm the hypothesis that plants suffer from N immobilisation if lignocellulose material of high C-to-N-ratio is