Yield, and Nutrient and Soil Loss Comparisons of Long-Term Tillage and Management System Trials:NC.

Agricultural non-point source pollution is a concern for both the farmer maintaining soil resources and the protection of water quality. A 20-year plus study at the Mountain Horticultural Crops Research Station located near Mills River NC (Appalachian ecosystem) compared tillage (conventional vs conservation) and management systems (organic vs conventional).  Four replications of five treatments included: conventional production with conservation tillage, conventional production with standard tillage (chisel plow), organic production with conservation tillage, organic production with standard tillage, and control (no added fertilizer and standard tillage). Early experiments compared different vegetable rotations, whereas later experiments measured nutrient runoff under sweet corn production.  During the water quality research, conventional plots received commercial nitrogen fertilizer (33-0-0) only as soil test levels demonstrated sufficient phosphorus and potassium.  Organic plots received a combination of pelletized poultry litter and leguminous cover crop. Water quality data (flow, nutrient and sediment concentrations, and deep soil samples, as a surrogate for nitrogen leaching), and sweet corn (Zea mays L.) yield and biomass data were collected. Sediment and sediment-attached nutrient load losses were influenced by tillage, whereas more soluble nutrients were affected by the nutrient source and rate and were typically a function of the management system. Sweet corn yields were usually higher in conventional management systems regardless of tillage, although not always. Seven years of sweet corn yield and three years of water quality data will be presented from this long-term tillage and cropping management experiment.