中国典型农田土壤磷素演化对长期单施氮肥的响应

 【目的】探讨中国典型土壤长期单施氮肥对土壤全磷和Olsen-P磷的影响。【方法】以土壤肥力与肥料长期定位试验为基础,应用常规化学分析法和数学统计方法,分析不同气候、不同耕作制度下15年单施氮肥（每季作物的施氮量为150 kg?hm-2）处理对6种典型土壤全磷和Olsen-P含量变化的影响。【结果】在长期单施氮肥条件下,耕作土壤全磷含量和土壤Olsen-P均呈下降趋势,全磷含量下降幅度为2.7%～25.0%。单施氮肥全磷含量下降幅度大于不施肥。Olsen-P含量下降有一定阈值,阈值大约为4 mg?kg-1。土壤Olsen-P含量下降率比全磷高几倍。耕层Olsen-P含量（y）与土壤磷素表观平衡（x）相关方程为y=0.0005x+3.9986,相关方程斜率很小,表明Olsen-P含量基本不受磷素表观平衡影响。【结论】长期单施氮肥加速了土壤全磷和Olsen-P的减少速度,其中全磷含量较低的土壤其下降幅度更大。

Response of Typical Soil Phosphorus Evolution to Long-term Single Nitrogen Fertilization

Objective] The influence of long term single nitrogen fertilization on the total P and Olsen-P of several typical soils in China was studied. Method] The phosphorus changes of 6 typical soils under different cropping systems and climates were studied based on a 15-year long-term fcrtilization experiment in China. Result] Results showed that total P and Olsen-P of all tested soils decreased, and the range of total P decrease was from 2.7% to 25.0%. The content of the total P with single nitrogen fertilization decreased more than that of non-fertilizer. The Olsen-P decreased to a value of about 4 mg·kg~(-1), and its decreased ratio was a few times higher than that of the total P. Conclusion] Therefore, single nitrogen fertilization accelerated the decrease of the total P and Olsen-P, and the soils with low total P decreased much more.