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

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.