aromatic structures arranged as spherical bodies that have a low degree of condensation and pyrochar as higher condensed layers of interlinked aromates All types of soil amendments do not only increase organic C contents, but they alsointeract with N transformations according to their chemical and physical properties, especially, when mineral fertilizers are applied additionally. Biochars can alter the rate of N cycling in soils and temporarily immobilise N in microbial biomass, especially if their C-to-N-ratio is wide. Some studies found reduced N leaching rates in the presence of biochar, which might be caused by an adsorption of NO3 from the soil solution to the surface of the char material or a similar buffering of plantavailable NH4. Different char materials may alter microbial nitrification and denitrification. For example, found increases in gross mineralisationand nitrification rates, leading to an enhanced N turnover and a transfer of N from a stable pool into a more labile pool in the form of NH4. The addition of C to soil via organic amendments might favour the process of dissimilatory NO3 reduction to NH4