氮肥运筹对稻田CH_(4)和N_(2)O排放的影响

Effects of Nitrogen Fertilizer Management on CH_(4) and N_(2)O Emissions in Paddy Field

开展了连续2 a(2019~2020年)的田间试验,通过设置不施肥(CK)、农户习惯施肥(CF)、二次追肥(TT)和有机肥替代20%化肥(OF)这4个处理,用静态箱-气相色谱法研究施肥对稻田CH_(4)和N_(2)O排放的影响,并综合水稻产量和综合温室效应(GWP)对单位水稻产量温室气体排放强度(GHGI)进行分析,探讨长江中下游典型水稻种植区增产减排的施肥方式.结果表明:1与CK相比,两年间各施肥处理均降低了CH_(4)排放,降幅为14.6%~25.1%;增加了N_(2)O排放,增幅为610%~1836%;2与CF相比,TT和OF处理均呈现增加CH_(4)排放和降低N_(2)O排放的趋势,TT和OF处理两年CH_(4)累积排放量年均值的增幅分别为1.8%(P>0.05)和14.0%(P<0.05);TT和OF处理两年N_(2)O累积排放量年均值的降幅分别为63.3%(P<0.05)和49.2%(P<0.05);3与CK相比,施肥均增加了水稻产量,降低了GHGI;与CF相比,OF和TT处理的水稻年均产量分别增加了17.0%和10.7%,GHGI分别降低了6.8%和13.7%,OF处理的增产效果优于TT处理,TT处理的减排效果优于OF处理.综合产量和温室气体减排而言,二次追肥(TT)和有机肥替代20%化肥(OF)均可在保证水稻产量的情况下,减少单位水稻产量的温室气体排放强度,实现增产减排.

Methane(CH_(4))and nitrous oxide(N_(2)O)are two extremely important greenhouse gases in the atmosphere.Nitrogen fertilizer is an important factor affecting CH_(4) and N_(2)O emissions in rice fields.Rational application of nitrogen fertilizer can not only promote high yields of rice but also reduce greenhouse gas emissions.Existing studies have shown that nitrogen reduction and optimal application can effectively improve the nitrogen use efficiency of rice on the basis of ensuring the yield and reduce the loss of N_(2)O caused by nitrification and denitrification of excessive nitrogen in soil.Fertilization times and fertilizer types have significant effects on CH_(4) and N_(2)O emissions in paddy fields.In this study,a field experiment was conducted for two consecutive years(2019-2020)to study the effects of fertilizer application on CH_(4) and N_(2)O emissions from rice fields by setting up four treatments consisting of no fertilizer(CK),customary fertilizer application by farmers(CF),twice fertilizer(TT),and 20%replacement of chemical fertilizer by organic fertilizer(OF)using static chamber-gas chromatography.Additionally,the effect of integrating rice yield and integrated global warming potential(GWP)on the greenhouse gas emission intensity(GHGI)per unit of rice yield was analyzed to explore fertilizer application for yield increase and emission reduction in a typical rice growing area in the middle and lower reaches of Yangtze River.The results showed that:1 compared with those of CK,the fertilizer treatments reduced CH_(4) emissions by 14.6%-25.1%and increased N_(2)O emissions by 610%-1836%in both years;2 compared with those of CF,both the TT and OF treatments showed a trend of increasing CH_(4) emissions and reducing N_(2)O emissions.CH_(4) emissions increased by 1.8%(P>0.05)and 14.0%(P<0.05),respectively.The annual average of N_(2)O emissions decreased by 63.3%(P<0.05)and 49.2%(P<0.05)in both the TT and OF treatments,respectively.3 Compared with that of CK,both fertilizer applications increased rice yield and reduced GHGI;compared with that of CF,the OF and TT treatments increased the average annual rice yield by 17.0%and 10.7%,respectively,and reduced GHGI by 6.8%and 13.7%,respectively.The OF treatment had a better yield increase than that of the TT treatment,and the TT treatment had a slightly better emission reduction than that of the OF treatment.In terms of combined yield and GHG emission reduction,both twice fertilizer(TT)and 20%replacement of chemical fertilizer by organic fertilizer(OF)could reduce the intensity of GHG emission per unit of rice yield and achieve yield increase and emission reduction while ensuring rice yield.