Two theories about the nature of phosphate in soil are current. One holds that soil phosphate is mostly present as particles of iron, aluminium and calcium phosphates: the precipitate‐particulate theory. The other holds that phosphate is mostly adsorbed and penetrates heterogeneous, variable‐charge particles: the adsorption‐penetration theory. This is the only theory that is consistent with and can be deduced from observations. It is my contention that the persistence of the precipitate‐particulate theory leads to: wasted research effort in trying to identify the supposed phosphate fractions; failure to recognize the long‐term changes in soil phosphate due to repeated applications, and thus to over‐fertilisation; and misapprehension about the effects of pH on phosphate availability.

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比较两种关于土壤磷酸盐性质的理论

关于土壤中磷酸盐性质的两种理论是最新的。一种观点认为，土壤磷酸盐主要以磷酸铁，铝和钙的颗粒形式存在：沉淀-颗粒理论。另一种观点认为，磷酸盐主要被吸附并渗透到非均质的可变电荷颗粒中：吸附渗透理论。这是唯一与观察结果一致并可以推论得出的理论。我的观点是，沉淀-颗粒理论的持续性导致：试图识别假定的磷酸盐组分的研究工作浪费了；由于重复施用以及过度施肥而未能认识到土壤磷酸盐的长期变化；以及对pH值对磷酸盐有效性的影响的误解。