水肥耦合对稻田氨挥发及水稻产量的影响

Effects of water and fertilizer coupling on ammonia volatilization and rice yield in paddy fields

水分、施肥管理是减少稻田氨挥发损失的重要农业管理措施,然而目前关于水肥耦合对于稻田氮素气态损失影响的研究还较少。本研究采用常规灌溉(W1:干湿交替灌溉)、节水灌溉(W2:全生育期湿润无明水)与不同施氮量(N1:常规施氮,353.86 kg/hm^(2);N2:减施20%氮肥,283.09 kg/hm^(2))相互耦合,设W1N1、W1N2、W2N1和W2N2共4个处理,通过盆栽试验对水稻不同生育期的氨挥发通量、土壤铵态氮含量以及水稻产量进行观测。结果表明,W1N1、W1N2、W2N1、W2N2的氨挥发总量分别为66.07 kg/hm^(2)、47.70 kg/hm^(2)、43.45 kg/hm^(2)、34.42 kg/hm^(2)。相同施氮量下,节水灌溉可降低27.84%~34.24%的总氨挥发累积量,其中在基肥施用后和分蘖肥施用后可分别降低8.00%~61.40%和47.03%~76.82%的稻田氨挥发。在节水灌溉条件下,减施20.00%氮肥处理可减少20.78%的总氨挥发累积量。此外,W1N2、W2N2处理的氨挥发累积量及单位产量氨挥发量表现出较低水平,说明减氮耦合常规灌溉或者节水灌溉处理均可对稻田氨挥发起到很好的缓解作用。结构方程模型分析结果也表明,氮肥施用量是直接影响稻田氨挥发量的重要因素,从而间接影响水稻产量。但是,W2N1、W2N2处理均存在引起水稻显著减产和籽粒含氮量降低的风险。综合考虑各处理对减少氨挥发损失和水稻稳产的影响,本研究中干湿交替灌溉耦合减氮处理(W1N2)是一种较高效的稻田水肥管理方式。

Water and fertilizer managements are important agricultural management measures to reduce ammonia volatilization loss in paddy fields.However,there are few studies on the effects of water and fertilizer coupling on gaseous nitrogen loss in paddy fields.In this study,conventional irrigation(W1:dry-wet alternation)and water-saving irrigation(W2:wet and unseen water in the whole growth period)were coupled with different nitrogen application rates(N1:conventional nitrogen application,353.86 kg/hm 2;N2:nitrogen reduction by 20%,283.09 kg/hm^(2)).Four treatments(W1N1,W1N2,W2N1 and W2N2)were set up to observe the ammonia volatilization flux,soil ammonium nitrogen content and rice yield at different growth stages of rice by pot experiment.The results showed that the total ammonia volatilization of W1N1,W1N2,W2N1 and W2N2 was 66.07 kg/hm^(2),47.70 kg/hm^(2),43.45 kg/hm^(2)and 34.42 kg/hm^(2),respectively.Under the same nitrogen application rate,water-saving irrigation could reduce ammonia volatilization in paddy fields by 8.00%-61.40%and 47.03%-76.82%after the application of base fertilizer and tillering fertilizer,respectively,and reduce the total ammonia volatilization accumulation by 27.84%-34.24%.Under the condition of water-saving irrigation,the total ammonia volatilization accumulation could be reduced by 20.78%in N2 treatment.In addition,the accumulation of ammonia volatilization and ammonia volatilization per unit yield of W1N2 and W2N2 showed low levels,indicating that nitrogen reduction coupled with conventional irrigation or water-saving irrigation could alleviate ammonia volatilization in paddy fields.In addition,the results of structural equation model showed that the nitrogen application rate was an important factor that directly affecting the ammonia volatilization in paddy field,thus indirectly affecting the rice yield.However,W2N1 and W2N2 had the risk of reducing rice yield and grain nitrogen content.Considering the effects of various treatments on reducing ammonia volatilization loss and stable yield of rice,dry-wet alternate irrigation coupled with nitrogen reduction(W1N2)is a more efficient way of water and fertilizer management in paddy field.