Eutrophication is one of the most important environmental issues concerning aquatic ecosystems today. Agricultural runoff is one of the primary sources of nutrients contributing to eutrophication. Phosphate, a key component of most fertilizers, is often the limiting nutrient in freshwater ecosystems. By measuring phosphate concentration in soil across a location gradient, it is possible to gain information as to how this nutrient moves through terrestrial systems and into surface water bodies. The location for this study is Babe + Sage Farm in Gordon, GA. Babe + Sage is a small sustainable farm just below the Fall Line in the Georgian coastal plain region. Farmers at this site have been using organic fish-based fertilizers in recent years. Results from previous testing at adjacent cultivated sites indicate high soil phosphate concentration. The purpose of this study is to assess how high soil phosphate from cultivated areas affects the surrounding environment. This study uses a soil desorption technique to quantify plant available phosphate originating from soil particle surfaces in the soils down-flow of the cultivated fields. The desorption tests were used to simulate runoff conditions in the coastal plain of Georgia. A pH of 4.6 was used to approximate the pH of local natural rainwater. Preliminary studies have shown high concentrations of phosphate in soils close to the fields, and, in general, phosphate desorptive capacity decreasing with increased distance from the fields, as expected. After testing overland runoff samples, we found high concentrations of phosphate travelling across the soil surface. The high concentration of phosphate in the overland runoff that was sampled raises our concern and increases the need for further testing. This research group will continue to test phosphate movement via overland flow in this system, and begin to investigate subsurface transport and particle-facilitated transport.

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