Effect of biochar amendment on yield and methane and nitrous oxide emissions from a rice paddy from Tai Lake plain, China

A field trial was performed to investigate the effect of biochar at rates of 0, 10 and 40 t ha(-1) on rice yield and CH4 and N2O emissions with or without N fertilization in a rice paddy from Tai Lake plain, China. The paddy was cultivated with rice (Oryza sativa L. cv. Wuyunjing 7) under a conventional water regime. Soil emissions of CH4 and N2O were monitored with a closed chamber method throughout the whole rice growing season (WRGS) at 10 day intervals. Biochar amendments of 10 t ha(-1) and 40 t ha(-1) increased rice yields by 12% and 14% in unfertilized soils, and by 8.8% and 12.1% in soils with N fertilization, respectively. Total soil CH4-C emissions were increased by 34% and 41% in soils amended with biochar at 40 t ha(-1) compared to the treatments without biochar and with or without N fertilization, respectively. However, total N2O emissions were sharply decreased by 40-51% and by 21-28%, respectively in biochar amended soils with or without N fertilization. The emission factor (EF) was reduced from 0.0042 kg N2O-N kg(-1) N fertilized with no biochar to 0.0013 kg N2O-N kg(-1) N fertilized with biochar at 40 t ha(-1). The results show that biochar significantly increased rice yields and decreased N2O emission, but increased total CH4 emissions. Summary calculations based on this experiment data set provide a basis for estimating the potential reductions in GHG emissions that may be achieved by incorporating biochar into rice paddy soils in south-eastern China. (c) 2010 Elsevier B.V. All rights reserved.