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Effects of different rotation systems on greenhouse gas (CH4 and N2O) emissions in the Taihu Lake region, China.

HU An-yong1,2, SUN Xing1, LIU Qin1*   

  1. (1Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China; 2University of Chinese Academy of Sciences, Beijing 100049, China)
  • Online:2016-01-18 Published:2016-01-18

Abstract: We conducted a greenhouse gas emissions study of different rice-based cropping systems in the Taihu Lake region. The results indicated that the seasonal CH4 emission initially increased, but declined over time. CH4 emission mainly occurred during the early stages of rice growth and decreased after the paddy soil dried. N2O emission mainly occurred during the fertilizer application and paddy field drying stages. Compared with N2O emission, CH4 emission contributed significantly more to the global warming potential (GWP) during the rice season. The proportion of CH4 emission to the total greenhouse gas emissions, which this study aimed to reduce, ranged from 94.7%-99.6%. CH4 emissions and their GWP during the rice season varied significantly under different rotation systems, with the order of wheat-rice rotation>Chinese milk vetch-rice rotation>fallowrice rotation, while the N2O emissions and their GWP exhibited no significant differences. Compared with no nitrogen fertilization, applying N fertilizer significantly reduced CH4 emission and GWP of the Chinese milk vetch-rice rotation. However, CH4 emission and GWP did not vary with N application rates. The rice yield was largest when the N application rate was 240 kg·hm-2. Taking economic and environmental benefits into account, we found that a N application rate of 240 kg·hm-2 and a strawreturn application of Chinese milk vetch not only reduced greenhouse gas emissions but also achieved the highest rice grain yield, which was recommended as a suitable cropping system for the Taihu Lake region.