氮肥模式对稻田温室气体排放和产量的影响

为探明不同施肥模式对稻田温室气体排放和水稻产量的影响,本研究以江汉平原一季中稻为研究对象,通过大田试验设置5个氮肥处理:不施氮肥(CK)、农民习惯施肥(FFP)、实时氮肥管理(RTNM)、精确定量施氮(PQNA)和一次性施肥(OOF),采用静态箱-气相色谱法研究了稻田CH4和N2O排放特征。结果表明:与CK相比,FFP、PQNA、RTNM和OOF显著增加了CH4和N2O排放。FFP、PQNA和RTNM处理CH4排放并没有显著差异,但是OOF处理比FFP处理CH4减排27.5%;RTNM和OOF处理比FFP处理N2O排放分别减少了23.1%和25.0%。与FFP相比,OOF并没有降低水稻产量,而RTNM和PQNA显著增加了水稻产量。OOF较FFP、RTNM和PQNA处理增温潜势(GWP)分别减少了27.4%、12.5%和18.5%。PQNA、RTNM和OOF处理的温室气体排放强度(GHGI)较FFP分别降低了22.2%、24.4%和26.7%。研究表明,采用合理的施肥模式,在保障水稻产量的同时,能够减缓稻田温室气体排放,实现丰产增效和环境友好。在所有施肥模式中,OOF具有最低的GWP,同时能够维持水稻产量并减少追肥次数,是一种低碳丰产的施肥技术,值得在江汉平原大面积推广。

Effects of different nitrogen regimes on greenhouse gas emissions and grain yields in paddy fields

To explore the impacts of different N regimes on greenhouse gas emissions and rice grain yield, a field experiment was conducted to examine the greenhouse gas emissions and rice grain yield under no N fertilizer input(CK), local farmer fertilization practice(FFP), real-time N management(RTNM), precise and quantitative N application(PQNA), and one-off fertilization(OOF)in paddy fields of Sanhu Farm, Jiangling City. The results showed that FFP, PQNA, RTNM, and OOF significantly increased the CH₄ and N₂O emissions compared with CK. There were no significant differences in CH₄ emissions between FFP, PQNA, and RTNM. Moreover, compared with FFP, OOF decreased CH₄ emissions by 27.5%, while RTNM and OOF decreased N₂O emissions by 23.1% and 25.0%, respectively. Rice grain yield showed few differences between FFP and OOF. RTNM and PQNA significantly increased the rice grain yield compared with FFP. The lowest global warming potential(GWP)was provided by OOF, which was 27.4%, 12.5%, and 18.5% lower than that of FFP, RTNM, and PQNA, respectively. The greenhouse gas emission intensity of PQNA, RTNM, and OOF was 22.2%, 24.4%, and 26.7% lower than that of FFP, respectively. This study shows that the use of optimized N fertilizer management practices such as PQNA, RTNM, and OOF can not only reduce greenhouse gas emissions from paddy fields, but also ensure rice grain yield, thereby achieving the goals of high yield, high efficiency, and environmental friendliness. OOF has the lowest GWP and lowest topdressing rate without decreasing the rice grain yield, and can be widely used in the Jianghan Plain.