江汉平原秸秆还田配合氮肥减施对稻田CH_(4)和N_(2)O排放的影响

Effects of straw returning combined with nitrogen reduction on CH_(4) and N_(2)O emissions from paddy fields in Jianghan Plain

为研究江汉平原秸秆还田配合氮肥减施对稻田温室气体排放的影响,设置常规施肥(N)、油菜秸秆加常规施肥(S+N)、油菜秸秆加减氮20%施肥(S+N 80%)3种模式,采用静态暗箱气相色谱法监测稻田CH_(4)与N_(2)O排放速率和累积排放量,结果表明不同施肥处理CH_(4)排放总量范围为69.69~166.97kg/hm^(2),S+N处理较N处理CH_(4)累计排放量增加50.26%,S+N 80%处理较N处理减排CH_(4)达37.28%,以S+N 80%处理减排效果最好;各施肥处理N_(2)O累积排放量为0.49~0.72kg/hm^(2),S+N处理较N处理N_(2)O减排达27.28%,S+N 80%处理较N处理减排N_(2)O达31.94%,以S+N 80%处理减排效果最佳。此外,CH_(4)与N_(2)O之间存在极显著负相关(P<0.01),与NH_(4)^(+)-N存在极显著正相关(P<0.01),与土温存在极显著正相关(P<0.01),N_(2)O与土温存在极显著负相关(P<0.01)。进一步计算100a尺度下CH_(4)和N_(2)O的全球增温潜势(GWP)和温室气体排放强度(GHGI)可知,S+N处理较N处理GWP增加了44.75%,S+N 80%处理相较于N处理GWP减少了36.92%;S+N处理较N处理GHGI上升了32%,S+N 80%处理较N处理GHGI下降了36%,3种施肥模式对产量均无显著影响。由此可知,S+N 80%处理是一种值得推广的施肥方式。

In order to study the effect of straw returning combined with nitrogen reduction on greenhouse gas emission from paddy fields in Jianghan Plain,3 modes of conventional fertilization(N),rape straw plus conventional fertilization(S+N)and rape straw plus 20%reduction of nitrogen fertilization(S+N 80%)were set up.The emission rates and cumulative emissions of CH_(4) and N_(2)O from paddy fields were monitored by static dark box gas chromatography.The results show that the total emissions of CH_(4) from different fertilization treatments range from 69.69kg/hm^(2) to 166.97kg/hm^(2),the cumulative CH_(4) emissions under S+N treatment increase by 50.26%compared with that of N treatment,the CH_(4) emission reduction of S+N 80%treatment is 37.28%compared with that of N treatment,and the emission reduction effect of S+N 80%treatment is the best;The cumulative N_(2)O emission of each fertilization treatment is 0.49kg/hm^(2) to 0.72kg/hm^(2).The N_(2)O emission reduction of S+N treatment is 27.28%compared with that of N treatment,and the N_(2)O emission reduction of S+N 80%treatment is 31.94%compared with that of N treatment.The emission reduction effect of S+N 80%treatment is the best.In addition,there is a very significant negative correlation between CH_(4) and N_(2)O(P<0.01),a very significant positive correlation with NH_(4)^(+)-N(P<0.01),a very significant positive correlation with soil temperature(P<0.01),and a very significant negative correlation between N_(2)O and soil temperature(P<0.01).By further calculating the global warming potential(GWP)and greenhouse gas intensity(GHGI)of CH_(4) and N_(2)O at 100a scale,it can be seen that the GWP of S+N treatment is 44.75%higher than that of N treatment,and the GWP of S+N 80%treatment is 36.92%lower than that of N treatment;The GHGI of S+N treatment is 32%higher than that of N treatment,and the GHGI of S+N 80%treatment is 36%lower than that of N treatment.The 3 fertilization modes have no significant effect on yield.Therefore,S+N 80%treatment is a fertilization method worthy of popularization.