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Agroforestry on Marginal Lands for Biomass and Ecosystem Services  

Drs. Hal Liechty, Matt Pelkki, and Don White, Arkansas Forest Resources Center
Dr. Mike Blazier, Louisiana State University AgCenter  

Bioenergy markets can provide revenue to landowners on marginal lands in the Lower Mississippi Alluvial Valley (LMAV) where crop returns are low due to low fertility or risk.  Cottonwood and switchgrass are native to this region, grow on a wide range of soils, and produce substantial amounts of biomass.  Combining these two species in agroforests provides annual and periodic harvests of biomass along with valuable ecosystem services such as carbon sequestration, nutrient retention, and wildlife habitat.  Four levels of cottonwood and switchgrass cover were established in agroforests on marginal soils at three sites in in the LMAV in Arkansas and Louisiana in the spring of 2009.  Cottonwood production in the first five year rotation averaged 0.5 oven dry tons per acre per year while switchgrass production averaged 2.8 oven dry tons per acre per year.  Small mammal abundance and diversity were significantly greater in both switchgrass and cottonwood agroforests than in control treatments planted to a soybean-grain sorghum rotation.  Nitrate concentrations in soil water in the agroforest treatments were generally lower than those in control plots.  Initial results suggest that substantial biomass production from cottonwood and switchgrass can occur on marginal soils but production differs significantly among soils.  Cottonwood is very sensitive to common herbicide treatments applied to rice fields.  Where establishment and growth is adequate, ecosystem services are enhanced by cottonwood and switchgrass agroforests.  The agroforest system is being monitored through the second rotation of cottonwood, it is expected that yields will increase substantially from an established coppice bed

UA Division of Agriculture  -  Agricultural Experiment Station  -  Cooperative Extension Service  -  School of Forest Resources  -  UA-Monticello

Arkansas Forest Resources Center, P.O. Box 3468, 110 University Ct., Monticello, AR 71656
870.460.1052  -