A 2-year study on the effect of biochar on methane and nitrous oxide emissions in an intensive rice–wheat cropping system
Shuwei Wang, Shutan Ma, Jun Shan, Yongqiu Xia, Jinghui Lin, Xiaoyuan Yan
Biochar ›› 2019, Vol. 1 ›› Issue (2) : 177-186.
A 2-year study on the effect of biochar on methane and nitrous oxide emissions in an intensive rice–wheat cropping system
The impacts of biochar addition with nitrogen fertilizer (Urea-N) on greenhouse gas (GHG) fluxes and grain yields are not comprehensively understood. Therefore, we designed a field experiment in an intensive rice–wheat cropping system located in the Taihu Lake region of China and measured CH4 and N2O emissions for 2 consecutive years to examine the impacts of biochar combined with N-fertilizer on rice production and GHG flux. Three field experimental treatments were designed: (1) no N-fertilizer application (N0); (2) 270 kg N ha−1 application (N270); and (3) 270 kg N-fertilizer ha−1 plus 25 t ha−1 biochar application (N270 + C). We found that, compared with urea application alone, biochar applied with Urea-N fertilizer increased N use efficiency (NUE) and resulted in more stable growth of rice yield. In addition, biochar addition increased CH4 emissions by 0.5–37.5% on average during the two consecutive rice-growing seasons, and decreased N2O–N loss by ~ 16.7%. During the first growing season, biochar addition did not significantly affect the global warming potential (GWPt) or the greenhouse gas intensity (GHGI) of rice production (p > 0.05). By contrast, during the second rice-growing season, biochar application significantly increased GWPt and GHGI by 28.9% and 18.8%, respectively, mainly because of increased CH4 emissions. Our results suggest that biochar amendment could improve grain yields and NUE, and increased soil GWPt, resulting in a higher potential environmental cost, but that biochar additions enhance exogenous carbon sequestration by the soil, which could offset the increases in GHG emissions.
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