牛粪-化肥配施对水稻田氮磷迁移转化的影响

在控制外源N输入量相同的前提下，通过田间小区实验，探讨有机肥与化肥不同施用量（牛粪施用量：5，10，20t/hm²）对稻田田间土-水界面氮磷迁移转化特征的影响.结果表明：控制稻田水中NH₄⁺-N、NO₃^--N、TN和TP输出的最佳时期分别为施肥后的第5，30，7，20d，且TN和TP浓度随时间变化符合单指数衰减方程（0.7444≤R²≤0.9724；1.1×10^-6≤F≤0.0055）.采用牛粪部分代替化肥的施肥方式，在一定范围内能降低稻田退水中TN、TP输出负荷（41.8%、36.0%、64.3%；20.3%、39.1%、48.9%），还可以降低稻田水中N/P，降低水体富营养化风险.同时，牛粪的施用可提高土壤中脲酶和磷酸酶的含量，促进氮磷向植物可吸收形态转化.综合经济成本和生态效益核算，采用10t有机肥代替无机肥的处理是相对经济环保的施肥方法，该施肥方式下，氮磷年输出负荷分别为17.70，1.26kg/hm².

Effect of combined application of manure and chemical fertilizer on transportation and transformation of nitrogen and phosphorus in paddy field water

The manure (cattle dung) was applied instead of chemical fertilizer partially(the amount of manure:5t/hm², 10t/hm² and 20t/hm²) to study the environmental behavior of nitrogen and phosphorus in the paddy field during the growth period. The results showed the optimum periods for controlling NH₄⁺-N, NO₃^--N, total nitrogen (TN) and total phosphorus (TP) in paddy field were 5, 30, 7 and 20 days after fertilization. The changing in TN and TP concentrations with time were fit the first order reaction kinetic function(0.7444 ≤ R² ≤ 0.9724; 1.81×10⁶ ≤ F ≤ 0.0055). Cow dung partly replacing the inorganic fertilizer fertilization can reduce TN and TP output load by 36.0%~64.3% and 20.3%~48.9%) in the rice field water. The application of cow dung reduced the N/P in paddy field water, thus reducing the risk of water eutrophication. At the same time, the application of cow dung increased the contents of urease and phosphatase in the soil, which promoted the transformation of N and P into plant bioavailable forms. The best economical addition dose estimated was 10t/hm² for manure. The annual output loads of nitrogen and phosphorus was 17.70kg/hm² and 1.26kg/hm², respectively.