利用膜进样质谱法测定不同氮肥用量下反硝化氮素损失

利用膜进样质谱仪(MIMS)测定了太湖流域典型稻田不同氮肥施用梯度下,土壤反硝化氮素损失量,同时也对氨挥发通量进行了观测。根据两年的田间试验结果得到:在常规施氮处理(N300)下,每年平均有54.8 kg/hm~2 N通过反硝化损失,有约54.0 kg/hm~2 N通过氨挥发损失,分别占肥料施用量的18.3%和18.0%,两者损失量相当。通过反硝化和氨挥发损失的氮素量随着氮肥用量增加而增加,田面水的NH_4~+-N、NO_3~–-N、DOC和pH浓度影响稻田土壤反硝化速率。在保产增效施氮处理(N_270)下,氮肥施用量比常规减少10%,水稻产量增加了5.5%,而通过反硝化和氨挥发损失的氮素量分别下降了1.1%和3.1%,氮肥利用率提高了约5.5%。在增施氮肥处理(N375)下,因作物产量增加使得氮肥利用率比N300增加,但通过氨挥发和反硝化的氮素损失量也最大。因此,通过综合集约优化田间管理措施,降低氮肥用量,可实现增产增效的目的。

Quantitative Determination of N Loss Through Denitrification Under Different N Fertilizer Application Rates by Membrane Inlet Mass Spectrometry (MIMS)

In this study, using membrane inlet mass spectrometry (MIMS), the impacts of different rates of N fertilizer application on denitrification, as well as ammonia (NH3) volatilization, were investigated over two rice-growing seasons in the Taihu Lake region of China. In N300 treatment, N loss through denitrification and NH₃ volatilization were N 54.8 kg/hm² and 54.0 kg/hm² per year, respectively, and were 18.3% and 18.0% of N fertilizer application, respectively. The amount of N loss through denitrification and NH₃ volatilization were increased as the N fertilizer application increasing, and were significantly affected by NH₄⁺-N, NO₃^--N, DOC and pH of surface water. In N270 treatment, compared with N300, the rate of N fertilizer application was reduced by 10%, but the rice yield approximately increased by 5.5%, N losses through denitrification and NH₃ volatilization were decreased by 1.1% and 3.1%, respectively, and agronomic nitrogen efficiency (NUE) was increased by 5.5%. In N375 treatment, compared with N300, NUE was increased due to increased grain yield, but the amount of N losses through NH₃ volatilization and denitrification was also the largest. Thus, the aim to reduce N fertilizer application and increase rice yield and NUE could be achieved through integrated soil-crop system management (ISSM).