IN-SITU EVALUATION OF BEST MANAGEMENT PRACTICES FOR ANIMAL WASTE STORAGE IN MANTLED KARST – A CASE STUDY FROM THE SAVOY EXPERIMENTAL WATERSHED

Animal production is typically the favored agricultural practice in mantled karst terranes, owing to the poor, rocky soils associated with impure carbonate bedrock. Typically, animal production in karst areas creates environmental problems because of rapid, focused flow through soil and regolith. The effectiveness of a swine waste storage facility was examined in mantled karst terrane at the University of Arkansas' Savoy Experimental Watershed (SEW). The SEW is a long-term, multi-disciplinary research site aimed at determining the impacts of animal waste on ground water and surface water quality. The SEW is approximately 1250 hectares and encompasses parts of 6 different drainage basins. This study deals with one such potential problem, to pond and store wastewater generated by a swine growing facility. An anaerobic swine waste lagoon was constructed in compliance with U. S. Department of Agriculture (USDA) Natural Resource Conservation Service (NRCS) Conservation Practice Standard No. 313 on a topographic divide in Basin 2. A karst inventory of all relevant springs, seeps and sinking streams was conducted in the basin. Based on the inventory, nine shallow wells were augered to refusal in the epikarst. Shallow ground water was sampled from wells and springs for nutrients, bacteria, major cations and anions in high-flow and low-flow conditions. The clay liner of the lagoon was cored and analyzed for nutrients and bacteria to determine if a more rigorous amendment is needed in karst terranes to meet the NRCS conservation waste storage standard. Results from ground water sampling indicate elevated concentrations of chloride and nitrate as compared with non-agricultural land-use areas, but are comparable to levels from previous sampling efforts at the site prior to the construction of the swine facility. Future work plans include dye tracing and collection of a high-flow sample from an interceptor trench.