Nitrate and fecal coliform concentrations in silvopasture and pasture leachates
A major limitation to efficient forage-based livestock production in Appalachia is asynchrony of forage availability and quality with nutritional requirements of the grazer. Silvopasture is being studied to improve the seasonal distribution and persistence of high quality herbage, sustainability and environmental integrity of the agricultural landscape. Fundamental knowledge of the impacts of agricultural practices on water quality is needed to address producer goals and societal concerns. Water quality was monitored at the soil/bedrock interface under conventional pasture (CP), silvopasture (SP), and hardwood forest (HF) on a central Appalachian landscape. The pasture and silvopasture were rotationally grazed by sheep during the spring to fall grazing season (2004-2008). Geometric mean fecal coliform bacteria concentrations were greatest in SP (18.0 cfu 100 ml-1) with no difference between CP (7.5 cfu 100 ml-1) and HF (5.6 cfu 100 ml-1). Mean NO3-N concentration was lowest in SP (2.2 mg L-1) and greatest in CP (4.4 mg L-1) and HW (4.1 mg L-1). Mean NH4-N concentrations showed different trends with the lowest mean concentration in CP (0.7 mg L-1) and the greatest in SP and HW (2.6 mg L-1). The observations will be important information for the development of decision support tools for maximizing forage and livestock productivity, through silvopastoral management on sloping land of central Appalachia, while protecting surface and groundwater quality.