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Title: Tree effects on forage growth and soil water in an Appalachian silvopasture

Author
item DEBRUYNE, S - Virginia Polytechnic Institution & State University
item Feldhake, Charles
item BURGER, J - Virginia Polytechnic Institution & State University

Submitted to: Agroforestry Systems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/24/2011
Publication Date: 2/10/2011
Citation: Debruyne, S.A., Feldhake, C.M., Burger, J.A. 2011. Tree effects on forage growth and soil water in an Appalachian silvopasture. Agroforestry Systems. DOI: 10.1007/s10457-011-9376-5.

Interpretive Summary: Diversifying and increasing production from Appalachian hill-land pastures may be possible by planting desirable trees to convert pastures to silvopastures. However, we do not have a thorough understanding of how trees impact water availability for forage production. We measured soil water as a function of distance from black walnut and honey locust trees and compared levels to those under shade cloth growing in silvopasture. Soil water levels decreased more rapidly under trees after precipitation events compared to under shade cloth, but the differences were not sufficient to adversely affect forage production. These results suggest that appropriately spaced trees with economic value can be grown in pastures without compromising forage production to support animal grazing. This work is useful to agricultural scientists developing innovative production systems for small hill farms in Appalachia and other impoverished regions. Trees also provide environmental services such a shade for animals on hot days, habitat for wildlife, and improve on-site nutrient retention. It will benefit the Region’s economy by increasing and diversifying the income from small farms thus improving the quality of life in rural communities in an ecologically sound manner.

Technical Abstract: Silvopastures may have the potential to increase forage yields beneath trees compared to open pasture at some sites. This has been attributed to a combination of factors including improved water-use efficiency by shaded grass and increased water availability through hydraulic lift by trees. The objectives of this research were to determine if silvopastures changed forage mass production and available soil water, and to determine how these two factors were related. Sampling of forage mass and soil water was done at 1.0 m, 2.0 m, and 3.6 m from the tree stem, or plot center under honey locust (Gleditsia triacanthos L.), black walnut (Juglans nigra L.) and shade cloth in 2006 and 2007. Soil water was measured in the top 10 cm of soil using a capacitance probe, and at 30 cm intervals, from 45cm to 105 cm, using a neutron probe. Forage was collected to determine dry mass and annual yield. In 2006, forage mass was greater under black walnuts and honey locusts than under 70% shade cloth. In 2007, with a 50% shade cloth, forage growth was similar in all treatments. In both 2006 and 2007, soil moisture in the top 10 cm was higher under shade cloth compared to honey locust or black walnut. Similarities in forage mass between treatments in 2007 indicate that the differences in soil water were not biologically significant for forage growth. Lower forage mass under the 70% shade cloth in 2006 was due to suppressed growth from intense shading. The presence of trees in these pastures appeared to have no negative effect on soil water availability and forage growth.