石灰性土壤中磷肥后效的研究

通过五年田间定位试验的结果表明,磷肥具有明显而持久的后效。后效的大小和持续时间主要取决于磷肥的施用量;后效持续的时间与磷肥施用量之间是指数函数关系;当施磷处理耕层土壤速效磷水平降至与对照处理基本相同时,磷肥后效即告结束。

THE RESIDUAL EFFECT OF PHOSPHATIC FERTILIZER IN CALCAREOUS SOIL

Through 5-year studies in fixed field on this matter, we have obtained the following preliminary results, phosphatic fertilizer had significant and long-term residual effect, the degree of the effect depending on the quantities of phosphatic fertilizer applied, the lasting time of the residual effect was determined by the amounts of phosphatic fertilizer added, and the two variables varied in exponential correlation., The residual effect of the fertilizer could no longer appear when the available phosphorus in the plot treated with phosphatic fertilizer decreased to the same level as with no applicasion of phosphatic fertilizer.