Scott DeBruyne, Virginia Tech Department of Forestry, 228 Cheatham Hall (0324), Blacksburg, VA 24061, James Burger, 228 Cheatham Mail Code 0324, Virginia Tech, Virginia Tech, Department of Forestry, Blacksburg, VA 24061-0324, and Charlie M. Feldhake, Appalachian Farming Systems Research Center, United States Department of Agriculture, 1224 Airport Road, Beaver, WV 25813.
Silvopastures have been recommended as systems that decrease agricultural inputs to pastures while simultaneously improving soil quality and increasing carbon storage. Silvopastures in tropical areas have been shown to have different soil properties than associated pastures, with the degree of difference in the soil properties dependant on many factors including tree species, forage species, soil type, silvopasture age, and the distance of the soil from the tree. Tree effects on soils of temperate silvopastures are not well documented. The objective of this study was to determine the effect of black walnut (Juglans nigra L.) and honeylocust (Gleditsia triacanthos L.) on soil quality indicators as a function of time and distance from the tree. Soil samples were collected at points of increasing distance from the trees on 5 different slope positions in the spring of 2003 and the fall and winter of 2006. Bulk density near the trees was 4% lower than in open pasture. Compared to open pasture, soil potassium was 9% higher under honey locust and 4% lower under black walnut. There was no difference in soil carbon.