Effects of biochar addition on N2O and CO2 emissions from two paddy soils

Impacts of biochar addition on nitrous oxide (N 2 O) and carbon dioxide (CO 2 ) emissions from paddy soils are not well documented. Here, we have hypothesized that N 2 O emissions from paddy soils could be depressed by biochar incorporation during the upland crop season without any effect on CO 2 emissions. Therefore, we have carried out the 60-day aerobic incubation experiment to investigate the influences of rice husk biochar incorporation (50 t ha −1 ) into two typical paddy soils with or without nitrogen (N) fertilizer on N 2 O and CO 2 evolution from soil. Biochar addition significantly decreased N 2 O emissions during the 60-day period by 73.1% as an average value while the inhibition ranged from 51.4% to 93.5% ( P < 0.05–0.01) in terms of cumulative emissions. Significant interactions were observed between biochar, N fertilizer, and soil type indicating that the effect of biochar addition on N 2 O emissions was influenced by soil type. Moreover, biochar addition did not increase CO 2 emissions from both paddy soils ( P > 0.05) in terms of cumulative emissions. Therefore, biochar can be added to paddy fields during the upland crop growing season to mitigate N 2 O evolution and thus global warming.