ARS | Publication request: Comparing biomass yields of low-input high-diversity communities with managed monocultures across the central United States

Submitted to: BioEnergy Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 1, 2010
Publication Date: December 1, 2010
Repository URL: http://hdl.handle.net/10113/48502
Citation: Johnson, M., Kiniry, J.R., Sanchez, H., Polley, H.W., Fay, P.A. 2010. Comparing biomass yields of low-input high-diversity communities with managed monocultures across the central United States. BioEnergy Research. 3:353-361.

Interpretive Summary: There is substantial debate in the literature regarding where best to grow biofuel crops and which crops to grow. In this manuscript we mine the NRCS ecological site productivity and crop productivity databases to compare annual net primary productivity (ANPP) means for managed monocultures (alfalfa, coastal bermudagrass, and buffelgrass) as compared to unmanaged diverse plant communities growing on the same soils in the same counties. The resolution of this work is coarse, but it moves us forward in our understanding of mean ANPP levels under high input management as compared to low input, high-diversity (LIHD) management systems. There is contention in the literature over whether LIHD or conventional systems are the appropriate choice for biofuel production. This work also identifies a potentially invaluable tool (NRCS databases) that has been under-utilized in addressing expansion of cropping systems. Though our results suggest switchgrass monocultures produce more ANPP than diverse communities at any site assayed, we caution that biomass production should not be the only metric used in determining appropriate sites for land conversion.

Technical Abstract: Expansion of biofuel cropping systems is increasing pressure on food production, grazing, and conservation lands. Debate over the efficacy of converting diverse native plant communities to managed monocultures prompted us to mine the ecological site productivity and crop productivity databases maintained by USDA-NRCS. In 21 percent of 1,238 sites across NE, KS, OK, and TX, low-input native communities had greater or comparable biomass production rates as compared to managed alfalfa (Medicago sativa L.) or coastal bermudagrass [Cynodon dactylon (L.) Pers] monocultures, suggesting these sites should be maintained as or converted to low-input native communities. However, regression analysis indicated that switchgrass (Panicum virgatum L.) monocultures out-yield diverse systems at all examined sites. Biomass production potential should not be the only metric to determine appropriate land conversion.