Phosphate Reaction Dynamics in Soils and Soil Components: A Multiscale Approach

Macroscopic- to more recent molecular scale investigations have enhanced our knowledge of soil phosphorus (P) chemistry, including the retention/release mechanisms in soils and soil components. Phosphate uptake on metal (oxy)hydroxide and phyllosilicate mineral surfaces and in soils generally increases with decreasing pH. Rapid adsorption kinetics is generally observed on many soil adsorbents at acidic pH. P fixation mechanisms such as inner-sphere complexation and intra- and interparticle diffusion often result in slow P release (i.e., hysteresis and irreversible reactions), creating challenges in remediating agricultural soils with high accumulations of P. This chapter covers some of the historical soil P chemical research findings via macroscopic approaches but focuses on more recent molecular scale approaches for elucidating P retention/release mechanisms.