Impacts of biofuel-based land-use change on water quality and sustainability in a Kansas watershed

Authors: Witthaus, Lindsey; SINNATHAMBY, SUMATHY - Kansas Department Of Agriculture; STURM, BELINDA - University Of Kansas

Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2016
Publication Date: 8/19/2016
Publication URL: http://handle.nal.usda.gov/10113/63198
Citation: Yasarer, L.M., Sinnathamby, S., Sturm, B.S. 2016. Impacts of biofuel-based land-use change on water quality and sustainability in a Kansas watershed. Agricultural Water Management. 175:4-14. doi:10.1016/j.agwat.2016.05.002.

Interpretive Summary: Effective water resource management and planning require an understanding of potential water quality impacts from changes in watershed land-use and practices. The biofuel market, and the associated demand for grain crops, is one of the factors contributing to land-use change. In order to understand the potential impacts from further biofuel development, a watershed model was used to simulate agricultural land-use change involving increasing acreage of corn and grain sorghum, which are typically used for ethanol production. The Soil and Water Assessment Tool (SWAT) was used to estimate watershed loads of total nitrogen, total phosphorus, and sediment from 6 different scenarios the Perry Lake watershed in northeast Kansas. Perry Lake is a regionally important reservoir used as a source of municipal water. The model estimated that corn production has a higher water quality impact, but also a higher grain yield than grain sorghum production. Replacing these biofuel crops on existing hay or CRP land resulted in the largest impacts on water quality. While replacing winter wheat with biofuel crops produced much lower water quality impacts. These results provide important information when examining the impacts of biofuel development on water quality in the Central Plains and for water resource planning at the watershed-level.

Technical Abstract: The growth in ethanol production in the United States has sparked interest in potential land-use change and the associated environmental impacts that may occur in order to accommodate the increasing demand for grain feedstocks. In this study water quality and sustainability indicators are used to evaluate the impacts of land-use change to increase corn and grain sorghum acreage for biofuel production in the Perry Lake watershed in northeast Kansas. Water quality indicators include sediment loads per converted land acreage and the relative increase of total nitrogen, total phosphorus and sediment loads compared to the baseline conditions. Sustainability indicators include land-use, water use, and nutrient use efficiencies. Hay, Conservation Reserve Program (CRP), and winter wheat were selected as targeted land-uses for conversion to biofuel feedstocks. The Soil and Water Assessment Tool (SWAT) was used to evaluate 6 different scenarios, each at 10 land-use change increments, for a total of 60 simulations. Results demonstrate that increased corn production generates significantly greater sediment loads than increased grain sorghum production and larger relative increases in nutrient loads. Expansion of corn or grain sorghum cropland by replacing hay or CRP land-uses resulted in the highest sediment loads and relative increases in nutrient loads. Expansion of corn or grain sorghum by replacing winter wheat cropland produced the lowest relative changes in nutrient and sediment loads and therefore may be a more sustainable land-use change. Corn had a higher yield potential per km2 compared to grain sorghum, resulting in better land, nutrient and water use efficiencies.