四、关于氮素化肥的合理使用在氮肥施用方面的主要问题是如何减少损失和提高利用率,也就是保肥增效问题。氮肥施入土壤后损失的主要途径有三:1.直接挥发损失,以碳铵和氨水最为严重,尿素次之;2.铵态氮肥经过硝化作用随水流失;3.在土壤中经过反硝作用的脱氮损失。 Fourth, on the rational use of nitrogen fertilizers Nitrogen fertilizer application in the main problem is how to reduce losses and improve utilization, that is, fertilizer and efficiency issues. Nitrogen fertilizer applied to the soil after the loss of the main three ways: 1. The direct loss of volatility to ammonium bicarbonate and ammonia most serious, followed by urea; 2. Ammonium nitrogen fertilizer through the nitrification loss with the water; 3. In the soil after denitrification Of denitrification losses.