Ecological Modelling 222 (2011) 2430–2447 Contents lists available at ScienceDirect Ecological Modelling journa l h o me pa g e: www.elsevier.com/locate/ecolmodel Modeling water and soil quality environmental impacts associated with bioenergy crop production and biomass removal in the Midwest USA S.E. Powers a , J.C. Ascough II b,∗ , R.G. Nelson c , G.R. Larocque d a Department of Civil and Environmental Engineering, 103 CAMP, Clarkson University, Box 5700, Potsdam, NY 13699-5700, USA b USDA-ARS, Agricultural Systems Research Unit, 2150 Centre Ave., Bldg. D, Suite 200, Fort Collins, CO 80526, USA c Center for Sustainable Energy, Kansas State University, Manhattan, KS 66502, USA d Natural Resources Canada, Canadian Forest Service, Laurentian Forestry Centre, 1055 du P.E.P.S., P.O. Box 10380, Stn. Ste-Foy, Quebec, QC, Canada G1V 4C7 a r t i c l e i n f o Article history: Available online 12 April 2011 Keywords: Modeling APEX model Water and soil quality Soil carbon Environmental impacts Stover removal Switchgrass Crop production a b s t r a c t The removal of corn stover or production of herbaceous crops such as switchgrass (Panicum virgatum) or big bluestem (Andropogon gerardii) as feedstocks for bioenergy purposes has been shown to have signif- icant benefits from an energy and climate change perspective. There is potential, however, to adversely impact water and soil quality, especially in the United States Corn Belt where stover removal predom- inantly occurs and possibly in other areas with herbaceous energy crops depending upon a number of geo-climatic and economic factors. The overall goal of this research was to provide a thorough and mech- anistic understanding of the relationship between stover and herbaceous crop production management practices and resulting range of impacts on soil and water quality, with a focus on eastern Iowa, USA. Comparisons of the production of herbaceous bioenergy crops to continuous corn (Zea mays L.) and corn- soybean (Glycine max L.) rotations on five different soils representative of the region were performed. Indices for total nutrient (nitrogen and phosphorus) loss to surface water and groundwater, total soil loss due to water and wind erosion, and cumulative soil carbon loss were derived to assess long-term sustainability. The Agricultural Policy/Environmental eXtender (APEX) agroecosystem model was used to quantify the sustainability indices and to generate sufficient data to provide a greater understanding of variables that affect water and soil quality than previously possible. The results clearly show the superi- ority of herbaceous crop production from a soil and water quality perspective. They also show, however, that compared to traditional cropping systems (e.g., corn-soybean rotations with conventional tillage), soil and water quality degradation can be reduced under certain conditions at the same time stover is removed. Published by Elsevier B.V. 1. Introduction The specifics of the United States Energy Independence and Security Act (EISA), signed into law December 2007, combined with the success of research efforts focusing on cellulosic biomass con- version processes, have heightened attention given to increased utilization of a diversified biomass resource portfolio for alternate energy production to meet the growing liquid fuel demands of the United States of America (USA). Between now and 2022, the USA has a goal of producing 36 billion gallons of renewable biomass- based fuel per year, of which a maximum annual production of 15 billion gallons of ethanol will be derived from corn starch with the remaining volumes derived from cellulosic and lipid-based feed- stocks. There is already substantial debate over the impacts of the ∗ Corresponding author. Tel.: +1 970 492 7371; fax: +1 970 492 7310. E-mail address: jim.ascough@ars.usda.gov (J.C. Ascough II). corn ethanol goals on our environmental and social systems. There- fore, we need to carefully consider how to best identify suitable cellulosic crops and utilize them in ways to ensure long-term and environmentally sustainable yields. The harvest of corn stover and production of herbaceous crops as cellulosic feedstocks for alternative biomass purposes have been shown to have energy benefits, and their conversion to alternative energy sources can help reduce dependence on imported crude oil and net emissions of greenhouse gases. There is a potential, how- ever, to adversely impact water and soil quality, especially in those areas where large-scale stover supplies exist and stover removal may be most economical. A study sponsored by the National Renewable Energy Laboratory (NREL) and the US Department of Energy (DOE) showed that the use of corn stover as a feedstock for ethanol production in Iowa, USA, could be done without adversely impacting soil health, while providing significant energy and green- house gas benefits (Sheehan et al., 2004). However, the analysis was limited to stover and raised several questions, especially related to 0304-3800/$ – see front matter. Published by Elsevier B.V. doi:10.1016/j.ecolmodel.2011.02.024