Strategic switchgrass (Panicum virgatum) production within row cropping systems: Regional‐scale assessment of soil erosion loss and water runoff impacts

• Published in: Global change biology. Bioenergy Vol. 12; no. 11; pp. 955 - 967
• Main Authors: Wang, Enheng, Cruse, Richard M., Sharma‐Acharya, Bharat, Herzmann, Daryl E., Gelder, Brian K., James, David E., Flanagan, Dennis C., Blanco‐Canqui, Humberto, Mitchell, Robert B., Laird, David A.
• Format: Journal Article
• Language: English
• Published: Oxford John Wiley & Sons, Inc 01-11-2020; Wiley
• Subjects: Agricultural production; Agriculture; Annual precipitation; Biodiesel fuels; Biofuels; Biomass; Climate change; Conservation practices; Cropping systems; Crops; Daily Erosion Project; Decisions; Efficiency; erosion; Erosion rates; Estimates; Farms; Land resources; Land use planning; Loss reduction; marginal land; Natural resources; Panicum virgatum; perennial biomass crops; Precipitation; Raw materials; Renewable energy; Runoff; Soil conservation; Soil erosion; Soil erosion control; Soil improvement; Soil water; Subsidies; switchgrass; Water conservation; Water quality; Water resources; Watersheds; WEPP; United States > US
• ISSN: 1757-1693; 1757-1707
• DOI: 10.1111/gcbb.12749

A strong need exists for tools to assess the efficacy of conservation practices across large regions supporting informed policy decisions that may lead to better soil and water conservation while optimizing agricultural production options. Perennial warm‐season grasses (WSGs) such as switchgrass (Panicum virgatum), can be grown on marginally productive and/or environmentally sensitive lands to meet growing bioenergy demands while reducing water runoff and soil erosion compared to current row crop systems. Quantifying the soil and water conservation effects of WSG when strategically placed on the landscape would help support decisions favoring both economic and environmental benefits. We used the Daily Erosion Project (DEP) to simulate the effects of WSGs on hillslope water runoff and soil loss for 2008–2016 across eight major land resource areas (MLRA) in the Midwest United States. Four different scenarios (baseline or existing conditions and switchgrass grown on slopes ≥3%, ≥6%, and ≥10%) were modeled. Across all hillslope groups replacing row crops with switchgrass reduced yearly water runoff and soil loss by 3.2%–12.1% and 43.7%–95.5% compared with the baseline levels, respectively. Water and soil conservation efficiency (water runoff reductions or soil loss reductions associated with 1% increase in switchgrass coverage) increased with slope as 10% > 6% > 3% for all MLRAs. Switchgrass replacement on slopes ≥10% reduced average soil loss estimates as much as 22.6 Mg ha−1 year−1 for the most erosive MLRA (baseline soil erosion rate of 28.6 Mg ha−1 year−1) and resulted in all MLRA erosion estimates ≤6.0 Mg ha−1 year−1. For soil loss, an apparent interaction existed between slope group and total annual precipitation; as annual precipitation increased, the difference in soil loss between slope groups increased. Soil loss was more sensitive to these factors than was water runoff. Policy supporting a renewable energy industry while strategically improving soil and water resources seems globally advantageous.
Spatial and temporal impact of strategic perennial warm season grass production on soil and water conservation in lieu of row crop production reveals favorable outcomes across multiple physiographic regions. The Daily Erosion Project modeling system used for this project illustrates a novel tool that utilizes a suite of remote sensing inputs and electronic databases to test scenarios and/or track change in soil erosion rates spatially and temporally across large regions.