This is a very readable book that contains a wealth of valuable information on the behaviour of phosphorus (P) in the soil, and its acquisition and utilization by crops. It will be of interest to agricultural scientists, extension workers, farmers and environmental managers.

The authors develop and explore the hypothesis that soil P is present in several inter-convertible pools that can buffer and maintain adequate phosphate (Pi) concentrations in the rhizosphere solution for root uptake and crop production. The replenishment of Pi in the soil solution arises from (1) desorption of Pi adsorbed to particulate matter, (2) solubilization of mineral salts and (3) conversion of organic matter to Pi. These processes occur at different rates, which are strongly dependent upon soil composition, environmental conditions and agronomic practice. The authors argue that, given sufficient time, most soil P sources can become available to crops and that, if these sources are P-replete, the use of P-fertilizers in crop production can be optimized by maintaining a ‘critical’ soil P concentration for a given soil type, climate and farming system through the addition of fertilizer P equal to crop P offtake plus P losses to the environment. In support of this hypothesis, the authors have produced an appendix containing detailed agricultural case studies from nine broadly defined agro-ecosystems that all illustrate equitable P balances and crop yields over a number of years. The authors conclude that the efficiency of soil and fertilizer P use can be improved greatly by appropriate management of the surface soil and its P content, as well as by optimizing the timing, placement and rates of P-fertilizer applications.