Biomass production with conservation practices for two Iowa watersheds

Authors: HA, MIAE - Argonne National Laboratory; WU, MAY - Argonne National Laboratory; Tomer, Mark; GASSMAN, PHILLIP - Iowa State University; ISENHART, THOMAS - Iowa State University; Arnold, Jeffrey; White, Michael; PARISH, ESTHER - Oak Ridge National Laboratory; COMER, KEVIN - Antares Group Incorporated; BELDAN, BILL - Antares Group Incorporated

Submitted to: Journal of the American Water Resources Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2020
Publication Date: 8/31/2020
Citation: Ha, M., Wu, M., Tomer, M.D., Gassman, P.W., Isenhart, T.M., Arnold, J.G., White, M.J., Parish, E.S., Comer, K.S., Beldan, B. 2020. Biomass production with conservation practices for two Iowa watersheds. Journal of the American Water Resources Association. 56(6):1030-1044. https://doi.org/10.1111/1752-1688.12880.
DOI: https://doi.org/10.1111/1752-1688.12880

Interpretive Summary: Use of agricultural lands to produce bioenergy feedstock presents both environmental challenges and benefits. This study evaluated various biomass production scenarios with conservation practices under different landscape designs. Two Iowa watersheds were selected for study: the South Fork of Iowa River and the headwaters of the Raccoon River. A simulation model, SWAT, was used to simulate hydrology and water quality under different scenarios with conservation practices and biomass production. Conservation practices and landscape design with a variety of feedstocks were shown to significantly improve water quality while supporting sustainable biomass production. Potential improvements in water quality could be up to 30% for nitrogen, 40% for phosphorous, and 70% for sediment. Results are of interest to agricultural, conservation, and energy feedstock industry stakeholders seeking to balance environmental and production performance for our agricultural landscapes.

Technical Abstract: Hydrologic modeling was used to estimate potential changes in nutrients, suspended sediment, and streamflow in various biomass production scenarios with conservation practices under different landscape designs. Major corn and soybean croplands were selected for study: the South Fork of Iowa River (SFIR) watershed and the headwater of the Raccoon River watershed (HRRW). A physically based model, the Soil and Water Assessment Tool (SWAT), was used to simulate hydrology and water quality under different scenarios with conservation practices and biomass production. SWAT models were calibrated and validated from 1996 to 2015 for SFIR and from 1997 to 2016 for HRRW (20 years), with corresponding climate data. Scenarios are based on conservation practices and biomass production; riparian buffer, saturated buffer, and grassed waterways as conservation practices; various stover harvest rates of 30%, 45%, and 70% with and without winter cover crops; and the conversion of marginal land to switchgrass. Conservation practices and landscape design with different feedstocks were shown to significantly improve water quality while supporting sustainable biomass production. Model results for nitrogen, phosphorus, and suspended sediments were analyzed for temporal and spatial scales with various degrees from hydrologic response units (HRUs) to watershed. Water quality could potentially improve by reducing pollutant loads by up to 20–30% nitrogen, 20–40% phosphorous, and 30–70% sediment, respectively.