Publication Type:Journal Article
Source:International Agricultural Engineering Journal , Volume 18, Number 3-4, p.15-23 (2009)
This paper provides estimates of the cost associated with inducing substantial conversion of land from production of traditional crops to switchgrass and its potential environmental consequences. Higher traditional crop prices due to increased demand for corn from the ethanol industry has increased the relative advantage that row crops have over switchgrass. Results indicate that farmers will convert to switchgrass production only with significant conversion subsidies. Potential environmental consequences of this conversion were analyzed using three stylized landscape usage scenarios, one with an entire conversion of a watershed to switchgrass production, a second with the entire watershed planted to continuous corn, and a third scenario that places switchgrass on the most erodible land in the watershed and places continuous corn on the least erodible. The Soil and Water Assessment Tool (SWAT) watershed-scale water quality model was applied to the Maquoketa River Watershed, which drains approximately 4,800 km2 of heavily cropped area in eastern Iowa. The modeling set up was well-calibrated for streamflow, sediment yield, and nutrient loadings including nitrogen and phosphorus, as evident by R2 and model efficiency (E) values greater than 0.7. Conversion of all existing croplands to switchgrass reduced sediment yield substantially by 84% and nitrate and phosphorus loads by 44 and 83% respectively, whereas converting everything to cropland increased all three by 23, 147, and 138% respectively. This study presents initial steps in identifying the economic as well as environmental consequences of a large-scale move to the bioeconomy.