从长期定位试验论红壤施磷的残效

红壤施磷的增产效果及残效的研究已有大量报道,但是连续20年观测施磷的残效未见报到.采用长期定位试验在累计6年施P2O5分别为720kg/hm2、1440kg/hm2、2160kg/hm2和2400kg/hm2的基础上进行观测.结果表明,停施磷20年,玉米籽粒产量、玉米穗粒数和千粒重的增产效果与施磷量成正相关;玉米籽粒、茎叶和土壤有效磷的含量与施磷量成正相关,说明红壤施磷后效可以延续20年.磷肥的残效随施磷量的增加而增加.单位磷肥的残效随施磷量的增加而递减.红壤旱地连续施磷量达到720～2400kg/hm2时,20年磷肥均有残效.连续6年施磷120kg/hm2,可停施4～5年,利用磷肥的后效来获得增产.在缺磷的红壤旱地上种植玉米,玉米吸收钾素的影响比吸收氮素的影响大.

Studies on the Residual Effect of Application Phosphorus on Red Soil of A Long-term Experiment

There are many reports about increasing yield of Application Phosphorus and lack of Phosphorus on red soil, but less reports about the residual effect of application phosphorus on red soil of a long-term experiment. The author spends about 20 years studying the residual effect of application phosphorus. The results showed as follow. There is the residual effect after stopping application different amount of phosphorus-20 years. Some years the residual effect is also higher than the quarter-phosphorus fertilizer efficiency. The amount of application phosphorus and the residual effect of phosphorus is positively correlated. Phosphate fertilizer units and the residual effect of phosphorus show decreasing trends. Different treatment of residual effect of phosphate fertilizer with time extended decline. Corn planted on the soil which lack of phosphorus will not affect its nitrogen absorption. Farmers applying manure on red soil drylands can promote the decomposition of insoluble phosphate, and increase available phosphorus content in soil. If after using P2O5120kg/hm2 on red soil drylands for six consecutive years, and then stopping 4 to 5 years, the output will increase because of the residual effect of application phosphorus. This article provides a scientific basis for scientifically applying phosphate on red soil drylands.