ARS | Publication request: Water Quality Impacts of Shifting towards a Corn Dominated Agricultural Watershed

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: March 15, 2010
Publication Date: April 21, 2010
Citation: Beeson, P.C., Doraiswamy, P.C., Sadeghi, A.M., Di Luzio, M., Tomer, M.D. 2010. Water quality impacts of shifting towards a corn dominated agricultural watershed [abstract]. Abs. 3, BARC Poster Day.

Technical Abstract: The South Fork of the Iowa River covers about 780 square kilometers (193,000 ac) and is one of 15 benchmark watersheds of the USDA Conservation Effects Assessment Project (CEAP). The watershed is dominated by potholes and artificial subsurface tile drainage needed to drain the hydric soils which cover 54% of the watershed. The South Fork watershed is 85% agricultural land with mainly either corn (Zea mays L.) or soybean [Glycine max L. (Merr.)]. The water quality has been impacted negatively by two recent changes, (1) the expansion of corn production and (2) the shift from soybean rotation to continuous corn. This shift towards corn cultivation is a result of the recent emphasis on renewable biofuels, in particular ethanol. In 2000, the entire watershed was 44% corn and 41% soybean, since then the disparity has grown and the maximum difference is seen in 2007 when the watershed was 59% corn and 21% soybean. This study uses SWAT/APEX to track changes in water quality due to expansion of corn production and the increased fertilizer applications resulting from continuous corn practices. Furthermore, some areas could see a switch to total corn production to meet federal ethanol production goals. This scenario was also simulated to show the impacts to water quality from large-scale expansion of corn cultivation.