中国稻田CH4排放对施氮的响应及影响因素Meta分析
毕业论文关键词 稻田；甲烷排放；氮肥施用；Meta分析
Response of CH4 emissions to nitrogen application in rice paddy fields: A meta-analysis in China
Abstract: Global warming is widely concerned, and CH4 emission makes important contribution to global warming in the rice paddy fields. Nitrogen application is one of the prerequisites to achieve high grain production of rice. However, it is less known how N application affects CH4 emissions in the rice paddy fields. Although many studies have been conducted to test the response of CH4 emissions to nitrogen application, high variation was reported and no consistent conclusion has been made at present. This study collected historical data (1995-2016) from the main rice growing districts in China, and quantitatively analyzed the response characteristics of CH4 emissions to nitrogen application with meta-analysis. It suggested that ammonium significantly reduced CH4 emissions by 1.68%. However, other fertilizers, including compound fertilizer, ammonium combined with organic fertilizer, compound fertilizer with organic fertilizer, greatly increased CH4 emissions by 78.78%、111.70% and 72.29%, respectively. CH4 emissions decreased first but then increased with increasing nitrogen input. It is 8.57 times for the response magnitude of CH4 emissions to nitrogen application under dry/wet alternative irrigation than under continuous flooding conditions. Under different tillage regimes, the response magnitude of CH4 emissions to nitrogen fertilization is as follows: rotary tillage>no tillage>ploughing tillage. The response magnitude of CH4 emissions to nitrogen under straw incorporation is 11.86 times of which under straw removal conditions. Under nitrogen application, CH4 emission in the seed-directed fields is 1.74 times for which under seedling transplanting fields; CH4 emission in the indica rice fields is 8.40 times for which in the japonica rice fields. In the single cropping rice systems, nitrogen significantly reduced CH4 emissions by 12.80%, but CH4 emissions were increased by 13.43%, 33.78%, 50.68% and 93.29% in the rice-wheat, rice-rape, rice-rice-legume and rice-rice-fallow systems, respectively. In the northeastern, northern and southwestern rice growing districts, nitrogen application significantly reduced CH4 emissions, while it significantly increased CH4 emissions in the middle and lower regions in the Yangtze River and South China. Thus, it is necessary to comprehensively consider the effects of water and nitrogen management, tillage and cultivation, farming system and climate on the response of CH4 to nitrogen applications.
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