ARS | Publication request: Effect of Loblolly Pine (Pinus taeda L.) Root Pruning on Alley Cropped Herbage Production and Tree Growth

Submitted to: American Society of Agronomy Meetings
Publication Type: Abstract Only
Publication Acceptance Date: June 2, 2008
Publication Date: October 5, 2008
Citation: Burner, D.M., Pote, D.H., Belesky, D.P. Effect of Loblolly Pine (Pinus taeda L.) Root Pruning on Alley Cropped Herbage Production and Tree Growth . 2008. American Society of Agronomy Meetings.

Technical Abstract: The competitive irradiance constraint of trees on the understory can be reduced by imposing standard silvicultural practices like pruning and thinning. Use of tillage to disrupt tree roots is an intensive practice which may improve herbage productivity at the crop-tree interface by reducing competition for water. Our objective was to compare tillage effects on loblolly pine (Pinus taeda L.) growth and yields of annual ryegrass (Lolium multiflorum Lam.) and pearl millet (Pennisetum glaucum (L.) R. Br.) in an alley cropping practice near Booneville, Arkansas. Alley crops were rotationally-grown in a 10-m wide alley (main plot) between bordering trees stems on one of three tillage treatments: control (surface tillage), rip followed by surface tillage, and trench plus root barrier followed by surface tillage. Topsoil water in May through September, herbage mass, and nutritive value were measured for each crop for 2 or 3 years in three subplots systematically arrayed (north, middle, and south) across the alley. Diameter and height of border trees were measured annually. Because of latitude and an east-west orientation of tree rows, the general tendency was that north subplots received more photosynthetically active radiation (PAR), and had higher topsoil temperature and less topsoil water than south subplots. Trenching effected a more uniform distribution of topsoil water among subplots compared to the other tillage treatments. Ripping and trenching improved herbage yield only one of two (annual ryegrass) or two of three (pearl millet) crops, and caused no consistent improvement in herbage nutritive value. Ripping and trenching significantly reduced loblolly pine dbh and height compared to the control. The imposition of intensive tillage practices could not be justified for annual herbage or wood fiber in this marginally productive loblolly pine alley cropping system.