INVESTIGATION INTO POTENTIAL NUTRIENT CONTENT FROM WOOD PROCESSING WASTE

At a site in northwest North Carolina, processed wood waste was land applied to agricultural fields under a permit issued by the NC Department of Natural Resources. Field monitoring shows high nitrogen levels in the groundwater below the agricultural fields, a violation of the discharge permit. This research project investigated the wood waste to see if it was a potential source of excess nitrogen. Leaching experiments were performed on the waste using deionized water to simulate rainfall events on the agricultural fields; the extract was analyzed for pH, total dissolved solids, soluble nitrogen species, soluble phosphorus, and dissolved organic carbon. A sequential leaching experiment was also performed to qualitatively assess the impact of multiple rainfall events on soluble salt production from the wood wastes. Initial experiments show that the waste is a potential source for dissolved nitrogen and phosphorus in the groundwater. However, all nitrogen was in the reduced form (NH₃, organic nitrogen), not in the form found at the field site. Additionally, phosphorus may also be a major issue at this site although levels do not currently exceed permitted levels.