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EXTENDED EFFECTS OF LIME AND COMPOST AMENDMENTS ON NUTRIENT RETENTION IN CECIL SOIL**

Abstract

Intensive agriculture in the 18th and 19th centuries, driven by cotton monoculture and a lack of erosion control practices, caused millions of acres of productive land in Georgia to lose topsoil, exposing the acidic, nutrient-depleted red clay that is now characteristic of this region. This study targets a highly weathered soil series common in the Southeast: Cecil soil (fine, kaolinitic, thermic Typic Kanhapludults) from Morgan County, Georgia. We hypothesize that the combined addition of lime (calcium carbonate) to improve soil pH and compost to increase nutrient inputs will increase phosphate retention and reduce phosphate mobility more effectively than compost alone, supporting a more long-term approach to restoring soil quality. The soil sample for this study was located through UC Davis’s SoilWeb and classified using Munsell color and texture analysis to determine sand, silt, and clay percentages. Lime requirement (LR) was determined using a rapid titration method with calcium hydroxide, and a pH kinetic experiment was conducted to evaluate how lime changed pH over time. Compost buffering capacity was analyzed through a titratable alkalinity test. A phosphate desorption experiment was then carried out to evaluate nutrient release and retention under varying lime concentrations (0–2.32 mg CaCO₃ g⁻¹ soil), with and without compost, to assess how these amendments influence phosphate mobility. GIS analysis was used to evaluate the distribution and condition of Cecil soil across the landscape. An erosion-risk map was generated by overlaying land-cover erosion potential with slope-percentage classes to identify high-risk areas within the Cecil soil extent. Lastly, a flow-accumulation map was created to identify areas that may experience runoff impacts relevant to amendment applications. Preliminary results show that lime raises soil pH and reduces phosphate mobility, compost increases soluble phosphate, and together they create an amendment that improves nutrient availability while limiting phosphorus loss in Cecil soil

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