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磷酸离子在土壤中的扩散速率极低,在质流中的含量也很少,所以磷在土壤中的移动很小,一般不超过三厘米。在石灰性土壤中,磷酸离子能与土壤中的钙发生反应,形成各种不同溶解度的磷酸盐而被固定下来。正因如此,磷肥的当季利用率仅为10—25％。由于磷肥当季利用率低,其它损失很小,故土壤中还残留一部分可供下季作物利用的磷酸盐。为了探讨磷肥后效的大小、延续时间和利用价值,进行了四年田间试验,现将结果概述如下。
Phosphate ions in the soil diffusion rate is very low, the content of the mass flow is also very small, so phosphorus in the soil movement is small, usually not more than three centimeters. In calcareous soils, phosphate ions react with calcium in the soil to form phosphates of various solubilities and are immobilized. Because of this, seasonal utilization of phosphate fertilizer is only 10-25%. Due to the low seasonal utilization of phosphate fertilizer and other losses, there is still some phosphate left in the soil for the next crop. In order to explore the size, duration and utilization of phosphate fertilizer aftereffect, conducted four years of field trials, the results are summarized below.