Forage Production and Nutritive Value in a Temperate Appalachian Silvopasture

Integrating trees into pasture may be an effective management tool to improve water, nutrient, and light allocation and increase total system productivity in Appalachia. We tested this hypothesis in a silvopasture near Blacksburg, VA. In 1995, black walnut and honey locust trees were planted within plots (r=3) of predominantly tall fescue pasture. Across a 12% slope, trees were planted to create treatments of low, medium, and high tree densities at shoulder, mid, and toe slope positions within plots of honey locust and black walnut. Sampling sites (n=54) under tree density and slope position combinations were harvested May to October at 35-d intervals in 2002 and 2003 for determination of yield and nutritive value characteristics. Soil surface temperature, forage canopy temperature, soil moisture, and photosynthetically active radiation were measured to determine forage responses to field treatments as functions of resource allocation. Tree density had the greatest effect on forage production and nutritive value. Across both years, yields were 16% greater (P=0.0006) at medium density (6130 kg/ha) compared to forage mass at low (5280 kg/ha)) and high density (4970 kg/ha, SE=130). Increasing tree density did not affect (P>0.2) ADF, CP, P, K, and Mg levels, but reduced (P<0.001) NDF and TNC, and increased (P<0.0001) ADL and Ca. Elevated soil surface and forage canopy temperatures limited forage production and nutritive value at low density, while low light levels were the limiting factor at high density. Moderating forage microclimate with appropriately spaced trees is an effective way to improve forage production in temperate pastures.