Response of soil carbon dioxide emission, soil organic carbon andmicrobial community to biochar addition with nitrogen optimizing

Abstract A three-year field study was conducted to investigate the CO2 emissions from irrigation wheat fields in response to biochar addition and nitrogen optimizing. Eight treatments were established: (1) control (without any fertilizers or biochar addition, CK), (2) nitrogen fertilizer application alone (300kg/hm2, N1), (3) biochar application alone (20t/hm2, B), (4) nitrogen fertilizer applied with biochar (N1B), (5) nitrogen fertilizer applied with 15% reduction (255kg/hm2, N2), (6) 15% reduction of nitrogen fertilizer + biochar (N2B), (7) nitrogen fertilizer applied with 30% reduction (210kg/hm2, N3), and (8) 30% reduction of nitrogen fertilizer + biochar (N3B), each treatment has three replicates. The objective of this study was to assess the impact of biochar addition and nitrogen optimized levels on soil carbon dioxide emission, soil organic carbon and microbial community. The findings indicated that the application of biochar and/or nitrogen fertilizer, particularly in combination, was observed to increase soil organic carbon and soil active organic carbon. Biochar application decreased CO2 emissions in wheat fields, compared with the non-amendment treatment. Biochar addition combined with optimized nitrogen also make a different CO2 emission rate. This improvement was attributed to the capacity of biochar to regulate soil microbial community composition, like soil functional diversity, soil microorganisms (fungi and bacterial), soil properties (pH, soil bulk density). In conclusion, biochar addition with nitrogen optimizing (B1N2) regime was determined to be the optimal approach for wheat field in irrigated region northern Xinjiang, resulting in enhanced soil organic carbon and the mitigation of carbon emissions. Nevertheless, further investigation of its long-term impact on farmland is recommended.