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Title: Nitrate and Fecal Coliform Concentration Differences at the Soil/Bedrock Interface in Appalachian Silvopasture, Pasture, and Forest

Author
item Boyer, Douglas
item Neel, James

Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/27/2009
Publication Date: 4/16/2010
Citation: Boyer, D.G., Neel, J.P. 2010. Nitrate and Fecal Coliform Concentration Differences at the Soil/Bedrock Interface in Appalachian Silvopasture, Pasture, and Forest. Agroforestry Systems, 79(1):89-96.

Interpretive Summary: Producers require dependable plant resources and management practices that improve the seasonal distribution and persistence of high quality herbage, sustainability and environmental integrity of the agricultural landscape. Producers also require a fundamental knowledge of the impacts of agricultural practices on water quality to address personal goals and societal concerns. The agroforestry practice of silvopasture is being studied for possible production and environmental benefits on Appalachian landscapes. Shallow wells were used to monitor water quality at the soil/bedrock interface under conventional pasture, silvopasture, and hardwood forest. The pasture and silvopasture were rotationally grazed by sheep during the spring to fall grazing season. Fecal coliform bacteria concentrations were greatest in silvopasture compared to pasture and forest. Nitrate concentrations were lowest in silvopasture. The higher fecal coliform bacteria concentrations in silvopasture probably resulted from a disturbed litter layer and macropores. Trend analysis shows that the fecal coliform bacteria concentrations in silvopasture are decreasing. The observations will be important inputs to the development of decision support tools for maximizing forage and livestock productivity while protecting surface and groundwater quality in the Appalachian region.

Technical Abstract: 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 (2.3 mg L-1) and greatest in CP (4.4 mg L-1) and HF (4.1 mg L-1). Mean NH4-N concentrations showed different trends with the lowest mean concentration in CP (0.5 mg L-1) and the greatest in SP and HF (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.