Effects of Black Walnut and Honey Locust on Forage Growth, Soil Water, and Soil Quality Indicators

The goal of this research was to determine the interactions between forage and tree components of a silvopasture system. Two studies were performed on adjacent sites established in 1995 at Virginia Tech's Kentland Research Farm. The objectives of the studies were to: 1. Determine the influence of honey locust and black walnut silvopastures on indicators of soil quality when compared to open pasture. 2. Determine if silvopasture systems changed forage mass production and soil water compared to open pastures.

The study on soil quality indicators was performed in a previously grazed silvopasture. Samples were collected from the upper 15 cm of soil at three distances from the tree rows. Total N (p= 0.0219), total C (p= 0.0216), extractable P (p= 0.063), extractable K (p= 0.0347) and microbial organic C (p= 0.0255) were greater in honey locust silvopastures. The highest concentration of soil nutrients and best soil physical and chemical properties were observed 1.5 m from the tree stem.

Forage growth and soil water were measured in silvopastures in 2006 and 2007. In 2006 there was higher forage growth in the black walnut and honey locust than beneath 70% shade cloth. In 2007, with a 50% shade cloth, forage growth was similar in all treatments. Initial soil water content was highest under shade cloth in 2006. In 2007 the rate of soil drying was lowest beneath the shade cloth.

The presence of trees did not negatively effect forage growth and silvopasture systems improved the soil quality indicators compared to open pasture.