黑土区水田化肥氮去向的研究

选取东北北部黑土地区水稻生产上施氮量、施肥方法和主要氮肥品种(尿素)为参数，采用示踪元素微区法和常规尿素小区法，连续2年系统地研究了水田化肥氮的去向。结果表明，化肥氮22．2％～46．1％进入了水稻体内，平均为37．7％，当年进入土壤中的残留氮12．7％～25．4％，氨挥发为8．8％～17．2％，作物对化肥氮的利用高低决定于施氮方法，化肥氮深施、混施均比表层施用利用率高，低施肥量化肥氮利用率比高施肥量利用率高，土壤残留量与施肥方法有关，深施和高施氮量均增加土壤残留，^15N试验证明，由于东北北部黑土比较粘重和土体构型的原因，在土层深度为80cm以下未检测出土壤残留化肥氮，示踪试验和小区试验证明，化肥氮的激发效应(PE)量和土壤残留氮量从该地区总体估算为大致平衡。

Fate of fertilizer nitrogen in paddy field of black soil region

Taking the N application rate, method and main varieties applied in paddy field of black soil in Northeast China as the parameters, a micro-plot tracer isotope trial and a normal urea plot trial were conducted for two years to study the fate of fertilizer nitrogen in paddy field. The results showed that 22.2%-46.1% of applied chemical fertilizer nitrogen was absorbed and remained in the paddy plant, and averaged 37.68%. About 12.7% to 25.4% of applied N during the same year was remained in the soil. The determined nitrogen losses rate through ammonia volatilization in a closed chamber system was 19.0%-44.2%. The use efficiency of chemical fertilizer N was influenced by the application method. Higher use efficiency would be obtained with deeper or mixing application method. The amount of nitrogen remained in soil were related to the application method, and the remained rate was increased with the amount and application depth increasing. The experiment with 15N showed that no 15N residue was detected below 80 cm in depth, which was because the heavy texture of the black soil. The results of the tracer isotope trial and the plot experiments showed that there was a rough balance between the amount of residual nitrogen in soil and the priming effect from chemical fertilizer nitrogen.