Nitrate and fecal coliform concentration differences at the soil/bedrock interface in Appalachian silvopasture, pasture, and forest

摘要

A major limitation to efficient forage-based livestock production in Appalachia is asynchrony of forage availability and quality with nutritional requirements of the grazer. 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. It was hypothesized that inorganic N and fecal coliform concentrations delivered in leachate to the soil/bedrock interface would be lowest in deciduous forest (HF) and highest in pasture (CP) with HF converted to silvopasture (SP) between the two. Piezometers were used to monitor water quality at the soil/bedrock interface under conventional pasture, SP, and hardwood forest. The pasture and SP were rotationally grazed by sheep during the spring to fall grazing season (2004-2008). Geometric mean fecal coliform bacteria concentrations (FC) were greatest in SP (18 FC 100 mLp#) with no difference between CP (7.5 FC 100 mLp#) and HF (5.6 FC 100 mLp#). Mean NO-N concentration was lowest in SP (2.3 mg Lp#) and greatest in CP (4.4 mg Lp#) and HF (4.1 mg Lp#), which were not significantly different. Mean NH-N concentrations showed different trends with the lowest mean concentration in CP (0.5 mg Lp#) and the greatest in SP (2.5 mg Lp#) and HF (2.6 mg Lp#), which were not significantly different. SP was shown to be a management option in the study area that reduces nitrate leaching, but should be considered cautiously in near-stream areas and near wells where fecal bacteria pollution can be problematic. This study makes an important contribution to our knowledge about interactions between landscape management and environmental quality of the Appalachian region. A diversity of land and forage management options are needed to maximize forage and livestock productivity while protecting surface and groundwater quality of the region.