Fate of phosphorus in the Lake Okeechobee watershed, Florida, USA: overview and recommendations

Lake Okeechobee, Florida, USA, currently is threatened by phosphorus (P) loading from the adjacent watershed north of the lake. The primary land uses in the watershed are beef cattle ranching and dairy farming for which there is a high net P import. The upland soils are predominantly poorly-drained, sandy Spodosols. Although the soils have low P retention capacity, about 80% of the applied P has remained in the soil in either unstable or stable forms. Phosphorus transport from the soil is controlled by relief, local drainage, and depth to the spodic horizon. Phosphorus in off-site runoff is partially assimilated in wetland and stream sediments, which have substantial long-term P retention capacities. Over the last 15 years, best management practices have been implemented to reduce P loads from agriculture. However, implementation has not been sufficient to meet P load reduction goals. Additional P control practices are needed to meet the target reduction goals. Several research and demonstration studies, have been conducted during the past decade to improve our understanding of the fate and transport of P. The results of the research were reviewed at a workshop held in West Palm Beach, Florida, USA, in June 1993, and are presented in this special issue of Ecological Engineering.