定位试验20年黄潮土速效磷养分的变化特征

利用黄潮土20年长期定位试验，研究了不同施肥条件下土壤速效磷含量的变化特征。结果表明，长期施用磷肥可以基本维持耕层土壤速效磷的水平；不施肥或单施氮肥以及配施厩肥，土壤速效磷含量随年代的变化，分别呈指数函数负相关和正相关。长期施用磷肥或厩肥可不同程度提高土壤剖面各层次速效磷含量，且磷肥与厩肥配施的效果较其单施更明显。在小麦－玉米轮作周期内，长期不同施肥处理可影响作物各生长期的土壤速效磷含量，但它们受外界环境条件影响而随季节变化的趋势基本一致。

Change features of soil available P in yellow fluvo-aquic soil for long-term stationary experiment

The change features of soil available P in different treatments were studied according to the stationary experiment in yellow fluvo-aquic soil for 20years. The results showed that application of P fertilizer could maintain the level of soil available P, there was an significantly negative correlation between content of soil available P and fertilization years under no fertilization or only applying N fertilizer, and the results of applying organic manure were on the contrary. Application of P fertilizer or organic manure for 20 years could increase the available P contents in soil vertical profile at various degrees , and application of P fertilizer in combination with organic manure had an obvious effect compared with the single application. In period of wheat-maize rotation, the soil available P contents in the crop growing periods effected by different treatments, but their change tendencies of soil available P with season were showing no difference.