Michael Blazier, LSU AgCenter, mblazier@agcenter.lsu.edu (Presenter)


Global interest in biomass-based fossil fuel substitutes is increasing, creating needs for new crops and cropping systems that will expand biofuel production. In the southeastern U.S., alley cropping agroforestry management systems in which switchgrass is cultivated between rows of loblolly pine or cottonwood are being explored. Such systems could produce an annually harvested, high-yield energy crop, wood waste for biofuel production, conventional forest products, and environmental services such as soil C sequestration and wildlife habitat. The objectives of this series of studies are to determine of the effects of tree overstory age and density, logging debris removal, and alley width on: (1) switchgrass and tree yields, (2) soil nutrient and microbial dynamics, (3) soil water, and (4) wildlife habitat. Switchgrass ground coverage was enhanced by loblolly pine overstory, but switchgrass yields were reduced by some levels of tree overstory tested. Soil microbial biomass and activity was greater in loblolly pine and switchgrass alley cropping systems than under loblolly pine alone. Exchangeable N in soil water was lower in switchgrass and cottonwood than in soybean and sweet sorghum. Small mammal populations were higher in switchgrass than in cottonwood, soybean, and sweet sorghum.