|Ascough Ii, James|
Submitted to: Journal of Environmental Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2005
Publication Date: 6/1/2006
Citation: Nelson, R.G., Ascough Ii, J.C., Langemeier, M.C. 2006. Environmental and economic analysis of switchgrass production for water quality improvement and alternative energy use in northeast kansas. Journal of Environmental Management. (2006). 79: 4 (336-347). Interpretive Summary: Results from this research indicate that switchgrass production on conventional agricultural cropland in northeast Kansas has distinct environmental advantages versus the traditional cropping rotations of corn-soybean, corn-soybean-wheat, grain sorghum-soybean, and grain sorghum-soybean-wheat. SWAT model simulations showed that four water quality indicators (sediment yield, surface runoff, NO3-N in surface runoff, and edge-of-field erosion) were reduced by an average of 99%, 55%, 34%, and 98% respectively over the range (0-224 kg N ha-1) of N application levels. Average net returns were $53.18, $68.49, $58.22, and $81.78 ha-1 for the rotations of corn-soybean, corn-soybean-wheat, grain sorghum, and grain sorghum-wheat, respectively. In nearly every scenario concerning switchgrass production at the five N application levels, at least 50% of the environmental savings in the water quality indicators could be attained at an edge-of-field cost of $22-$27.49 mton-1 or less. The total deliverable energy cost associated with using switchgrass as a propane substitute was calculated from break-even costs for all four cropping rotations. Deliverable energy costs ranged from a low of $6.54 GJ-1 to a high of $7.47 GJ-1. The magnitude of switchgrass water quality payments needed to achieve delivered energy costs of $5.68 GJ-1 were determined, and ranged from a low of $11.07 mton-1 equivalent to a high of $27.18 mton-1 equivalent depending upon switchgrass yield level.
Technical Abstract: The primary objectives of this research were to determine SWAT model predicted reductions in four water quality indicators (sediment yield, surface runoff, nitrate nitrogen (NO3-N) in surface runoff, and edge-of-field erosion) associated with producing switchgrass (panicum virgatum) on cropland in the Delaware Basin in northeast Kansas, and to evaluate the break-even cost of producing switchgrass versus conventional commodity crops. The magnitude of potential switchgrass water quality payments relating to using switchgrass as an alternative energy source were also estimated. SWAT model simulations showed that between 527,000 and 1.27 million metric tons (mton) of switchgrass could be produced annually across the basin depending upon nitrogen (N) fertilizer application levels (0 to 224 kg N ha-1). The predicted reduction in sediment yield, surface runoff, NO3-N in surface runoff, and edge-of-field erosion as a result of switchgrass plantings was 99%, 55%, 34%, and 98%, respectively. The environmental benefits would cost between $20 million and $36 million dollars per year, and the average annual cost per hectare for switchgrass ranged from about $190 with no N applied to around $345 at 90.7 kg N ha-1 applied. Edge-of-field cost per mton ranged from around $36 with no N applied to slightly over $25 at 90.7 kg N ha-1 applied. A majority of the switchgrass produced had an edge-of-field cost of $28 mton-1 or less. Savings of at least 50% in each of the four water quality indicators could be attained for an edge-of-field cost of $22-$27.49 mton-1.