Effect of Different Rice Irrigation Patterns on CH4 Emission from Paddy Field

摘要

Based on observation in situ with closed static chamber technique,field experiment has been carried out to investigate the effect of different rice irrigation patterns on the law of CH4 emission from paddy field.The results show that the total CH4 emission from controlled irrigation (CI) and flooding irrigation (FI)paddy field is 24.46g·m-2 and 39.88g·m-2 respectively,and the seasonal average of CH4 emission rate is 7.96mg·m-2·h-1 and 12.98mg·m-2·h-1 respectively,and the former is 39% less than the latter.There is no statistically significant difference on the mean emission rates of CH4 between two kinds of irrigation patterns during green stage to middle tillering stage of rice (p=0.87 ＞ 0.05);while during later tillering stage to ripening stage of rice the mean CH4 emission from CI paddy fields is highly significantly lower than that from FI paddy fields (p=0.00＜0.05).The seasonal variation of CH4 emission from CI paddy fields takes on distinct one-peak pattern,occurring at initial tillering stage of rice,over 10 days earlier than that from FI paddy fields.The diurnal variation of CH4 emission from CI paddy fields appears regular afternoon-maximum model,mainly at 13:00p.m.,but that from FI paddy fields appears random model.