Rethinking Soil Phosphate Chemistry: Towards a Shift in Conceptual Framework

Classical soil phosphorus (P) chemistry is based on the belief that fertiliser P precipitates as isolated iron, aluminium and calcium compounds, an opinion encouraged by fractionation schemes and textbook dogma. However, years of evidence indicate the paradigm to be incorrect. Evidence indicates that P rather gets adsorbed onto variable‐charge surfaces with subsequent penetration into particles, causing hysteresis in low‐P soils and reducing fertiliser effectiveness with time. As P accumulates in soils, hysteresis decreases and fertiliser efficacy stabilises. Likewise, long‐held supposition concerning the most favourable soil pH for crop growth and the role of phosphate‐solubilising bacteria is found to be misleading when the direct measurement of plant uptake is interrogated. Through the exposure of such misconceptions, we contend that there is a new paradigm of soil P chemistry that more satisfactorily explains experimental observations and informs sustainable fertiliser management.