nosZ and nosZ-II marker genes had been sequenced in order to investigate the impact of biochar on N2O reducers

N2O is a major greenhouse gas and the gross of anthropogenic N2O emission originates from agriculturally managed soils. The development of N2O mitigation strategies is a key challenge for the agricultural sector. Biochar as soil amendment is discussed as promising tool to mitigate N2O emissions. Biochar capacities to increase soil pH and to foster activity of specialized N2O reducers were proposed as possible mechanisms driving N2O mitigation after biochar addition. In order to test whether a shift in community composition of N2O reducers is also effective under field conditions we performed a field experiment assessing abundance and taxonomic composition of the functional marker genes nosZ and nosZ clade-II across a vegetation period under the cultivation of Zea mays. The liming effect of biochar was addressed by including a limed control treatment. After fertilization nosZ and nosZ clade-II gene copy numbers increased significantly in the biochar treatment. Biochar addition yielded in a significant shift in community composition of nosZ-II bearing bacteria beyond the sole liming effect after fertilization. Our results broaden our understanding of the functional impact of biochar on the N2O reducing microbial community to a field scale and might prove valuable for the development of N2O mitigation strategies.