Land management strategies for improving water quality in biomass production under changing climate

The Corn Belt states are the largest corn-production areas in the United States because of their fertile land and ideal climate. This attribute is particularly important as the region also plays a key role in the production of bioenergy feedstock. This study focuses on potential change in streamflow, sediment, nitrogen, and phosphorus due to climate change and land management practices in the South Fork Iowa River (SFIR) watershed, Iowa. The watershed is covered primarily with annual crops (corn and soybeans). With cropland conversion to switchgrass, stover harvest, and implementation of best management practices (BMPs) (such as establishing riparian buffers and applying cover crops), significant reductions in nutrients were observed in the SFIR watershed under historical climate and future climate scenarios. Under a historical climate scenario, suspended sediment (SS), total nitrogen (N), and phosphorus (P) at the outlet point of the SFIR watershed could decrease by up to 56.7%, 32.0%, and 16.5%, respectively, compared with current land use when a portion of the cropland is converted to switchgrass and a cover crop is in place. Climate change could cause increases of 9.7% in SS, 4.1% in N, and 7.2% in P compared to current land use. Under future climate scenarios, nutrients including SS, N, and P were reduced through land management and practices and BMPs by up to 54.0% (SS), 30.4% (N), and 7.1% (P). Water footprint analysis further revealed changes in green water that are highly dependent on land management scenarios. The study highlights the versatile approaches in landscape management that are available to address climate change adaptation and acknowledged the complex nature of different perspectives in water sustainability. Further study involving implementing landscape design and management by using long-term monitoring data from field to watershed is necessary to verify the findings and move toward watershed-specific regional programs for climate adaptation.