Evaluation of bioenergy crop growth and the impacts of bioenergy crops on streamflow, tile drain flow and nutrient losses in an extensively tile-drained watershed using SWAT

Authors: GUO, TIAN - Purdue University; CIBIN, RAJ - Pennsylvania State University; CHAUBEY, INDRAJEET - Purdue University; GITAU, MARGARET - Purdue University; Arnold, Jeffrey; SRINIVASAN, RAGHAVAN - Texas A&M University; Kiniry, James; ENGEL, BERNARD - Purdue University

Submitted to: Science of the Total Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2017
Publication Date: 2/1/2018
Publication URL: https://handle.nal.usda.gov/10113/5822902
Citation: Guo, T., Cibin, R., Chaubey, I., Gitau, M., Arnold, J.G., Srinivasan, R., Kiniry, J.R., Engel, B.A. 2018. Evaluation of bioenergy crop growth and the impacts of bioenergy crops on streamflow, tile drain flow and nutrient losses in an extensively tile-drained watershed using SWAT. Science of the Total Environment. 613-614:724-735.

Interpretive Summary: If large scale biofuel production meets US biofuel goals, it is important to study the impacts of such crops on water quantity and quality. We need to identify environment-friendly and productive systems for such production. In this study, the computer simulation model SWAT2012 with a new tile drainage routine and improved perennial grass and tree growth simulation was used to predict long-term annual biomass yields, streamflow, tile flow, sediment load, and nutrient losses under various bioenergy scenarios in an agricultural watershed in the Midwest. Model simulations were compared to those with current typical agriculture for the area. Simulated crop yields were similar to observed county yields of corn and soybeans, and were reasonable for Miscanthus, switchgrass and hybrid poplar. Removal of 38% of corn stover (3.7 Mg/ha/yr) with Miscanthus production on highly erodible areas and marginal land (17.5 Mg/ha/yr) provided the highest production. Streamflow, tile flow, erosion and nutrient losses were reduced under scenarios of bioenergy crop production on highly erodible areas and marginal land. Removing corn stovers did not change water quality. The increase in sediments in streams and nutrient losses in runoff with corn stover removal could be offset with combinations of other bioenergy crops. Potential areas for bioenergy crop production when meeting the criteria above were small, thus the ability to produce biomass and improve water quality was not substantial. Corn stover removal combined with bioenergy crops on highly erodible areas and marginal lands provides more biofuel production than current typical agricultural practices. It is beneficial to water quality, providing guidance for further research bioenergy crops in tile-drained watersheds in the Midwest.

Technical Abstract: Large quantities of biofuel production are expected from bioenergy crops at a national scale to meet US biofuel goals. It is important to study biomass production of bioenergy crops and the impacts of these crops on water quantity and quality to identify environment-friendly and productive biofeedstock systems. In this study, SWAT2012 with a new tile drainage routine and improved perennial grass and tree growth simulation was used to model long-term annual biomass yields, streamflow, tile flow, sediment load, and nutrient losses under various bioenergy scenarios in an extensively agricultural watershed in the Midwestern U.S. Simulated results from bioenergy crop scenarios were compared with those from the baseline. The results showed that simulated annual crop yields were similar to observed county level values for corn and soybeans, and were reasonable for Miscanthus, switchgrass and hybrid poplar. Removal of 38% of corn stover (3.74 Mg/ha/yr) with Miscanthus production on highly erodible areas and marginal land (17.49 Mg/ha/yr) provided the highest biofeedstock production. Streamflow, tile flow, erosion and nutrient losses were reduced under bioenergy crop scenarios of bioenergy crops on highly erodible areas and marginal land. Corn stover removal did not result in significant water quality changes. The increase in sediment load and nutrient losses under corn stover removal could be offset with the combination of other bioenergy crops. Potential areas for bioenergy crop production when meeting the criteria above were small, thus the ability to produce biomass and improve water quality was not substantial. The study showed that corn stover removal with bioenergy crops both on highly erodible areas and marginal land could provide more biofuel production relative to the baseline, and was beneficial to water quality at the watershed scale, providing guidance for further research on evaluation of bioenergy crop scenarios in a typical extensively tile-drained watershed in the Midwestern U.S.