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 predomina ntly poorly-drained, sandy Spodosols. Although the soils have low P re tention 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 hori zon. Phosphorus in off-site runoff is partially assimilated in wetland and stream sediments, which have substantial long-term P retention ca pacities. Over the last 15 years, best management practices have been implemented to reduce P loads from agriculture. However, implementatio n has not been sufficient to meet P load reduction goals. Additional P control practices are needed to meet the target reduction goals. Seve ral 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 We st Palm Beach, Florida, USA, in June 1993, and are presented in this s pecial issue of Ecological Engineering.