Rules and Impact Factors of Greenhouse Gases Emission in the Saline-Alkali Paddy Fields in Different Years

With the method of combining field sampling and plot test,we took saline-alkali paddy field of Qianguo county,Jilin province as an investigation object. According to the nature of soil in the area,we monitored CH4 and N2O which released from soil during rice growth period and tested the soil p H and soil organic carbon to analyze the law and reasons of greenhouse gas emission in the paddy fields. The results showed that N2 O emission from paddy fields presented three peaks with distinct seasonal patterns. Application of fertilizer provided additional reactive substrate,which affected N2 O emission significantly. Under flooding conditions,the main source of N2 O is a denitrification process,while after drainage,nitrification was the predominance. CH4 emission showed a single peak at rice tillering stage when rice grew vigorously. That deoxidation condition dominated in the deep water layer in the paddy fields provided suitable conditions for CH4 producing microorganisms,which result in the emergence of CH4 emission peak. The p H doesn't have an obvious influence on CH4 and N2O,while SOC content in soil and pattern of CH4 emission showed a significantly positive correlation.