Abstract
The search for the mediaeval philosopher’s stone and the search for effective phosphate solubilizing microorganisms are analogous. Both are based on an erroneous assumption about nature. Advocates for phosphate solubilizing microorganisms think that P is present in soils as discrete compounds of iron, aluminium, and calcium. This is not consistent with many observations. Rather, P is adsorbed on, and penetrates, into variable-charge surfaces. Further, phosphate solubilizing microorganisms often do not compete with microorganisms already present or produce acid under soil conditions. When responses do occur, they are more likely to be caused by effects of decreased pH on uptake of P by plant roots rather than on release of P by soil We are more likely to conserve resources and to decrease water pollution by understanding that previous applications have changed soil conditions so that subsequent applications are more effective, and much less phosphate is required.