Multi-environmental impacts of biofuel production in the US Corn Belt: A coupled hydro-biogeochemical modeling approach

Increased corn growth frequency and corn stover removal for ethanol production are two primary sources to meet the rising demand for biofuels; however, these measures may potentially cause adverse environmental consequences in multiple aspects, such as water, carbon, and nitrogen, that are not well understood. To address this issue, a newly coupled hydro-biogeochemical model, SWAT-DayCent, was used to investigate the comprehensive environmental impacts of increased corn cultivation frequency and stover removal in a typical agricultural basin in the U.S. Corn Belt. Our results indicate that both the soil water and water yield decreased slightly under projected increased corn cultivation frequency and residue removal. The NO3-N load increased considerably by 44.3% and 130.0% when the crop rotation converted from the typical corn-soybean to corn-corn-soybean and continuous corn, respectively. However, sediment yield and SOC depletion showed decreases by 6.2-15.5% and 9.3-25.4% when increasing the corn cultivation. For the stover removal, NO3-N load decreased slightly (1.0-6.2%), but the sediment yield and SOC depletion increased by 1.8% and 8.0% when 30% of stover were harvested, and these two percentages would reach 35.2% and 24.4% when 90% of stover were harvested. In summary, increased corn cultivation frequency would primarily degrade water quality, while stover removal may increase the soil degradation risk by increasing sediment yield and SOC depletion at the watershed. This study provided comprehensive environmental impacts of bioenergy production and can be valuable for decision making towards sustainable bioenergy development and watershed eco-environmental management. (C) 2019 Elsevier Ltd. All rights reserved.