南方稻田活性氮损失途径及其影响因素

基于文献数据,研究了南方不同稻区水稻生长期氧化亚氮排放(N₂O排放)、硝态氮或铵态氮淋洗(N淋洗)、硝态氮或铵态氮径流(N径流)、氨挥发(NH₃挥发)的差异及其影响因素.结果表明: N₂O排放、N淋洗和N径流主要发生在长江流域单季稻区,损失量分别为1.89、6.4和10.4 kg N·hm^-2,损失率分别为0.8%、3.8%和5.3%,较高施氮量和稻田土壤干湿交替可能是主要原因；NH₃挥发主要发生在华南晚稻,损失量和损失率分别为54.9 kg N·hm^-2和35.2%,晚稻生长期较高的温度可能是NH₃挥发较大的主要原因.田间优化管理措施减少某一途径氮损失的同时可能会增加另一种途径氮素损失,实际生产中应综合考虑田间管理措施对各种活性氮损失的影响,活性氮损失量随着水稻产量水平的提高而增加,主要是因为施氮量也在逐渐增加.随着氮肥偏生产力的增加,N₂O排放、N淋洗和N径流损失率逐渐下降,因此,努力减小单位产量的氮损失,是协同提高作物产量和氮肥利用效率的重要途径.

Reactive nitrogen loss pathways and their effective factors in paddy field in southern China.

Based on the literature data, the N₂O emission, N leaching, N runoff and NH₃ volatilization were compared from different rice production regions and their effective factors were evaluated. The results showed that N₂O emission, N leaching and N runoff in single rice in Yangtze River basin were higher than in other rice production regions, with N loss of 1.89, 6.4 and 10.4 kg N·hm^-2, and N loss rate of 0.8%, 3.8% and 5.3%, respectively. The high N₂O emission, N leaching and N runoff in these regions might be attributed to high rate N application and dry wet alternation. The NH₃ volatilization was the highest in late rice in southern China, with N loss of 54.9 kg N·hm^-2 and N loss rate of 35.2% due to higher temperature at late rice growing stage. In the field, the practice often decreased one reactive N loss but increased another one, indicating that intergated practical management is necessary to reduce reactive N loss. Reactive N loss often increase with increasing grian yield, which is associed with the high rate N application. The N₂O emission, N leaching and N runoff decreased with increasing the partial factor productivity of applied N (PFP). Therefore, reducing N losses per unit of yield is necessary for integrating higher yield with minimum environmental pollution.