Location: National Soil Erosion ResearchTitle: Quantifying the effects of conservation practice implementation on predicted runoff and chemical losses under climate change Author
Submitted to: Agricultural Water Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/17/2017
Publication Date: 3/6/2017
Citation: Wallace, C.W., Flanagan, D.C., Engel, B.A. 2017. Quantifying the effects of conservation practice implementation on predicted runoff and chemical losses under climate change. Agricultural Water Management. 186:51-65. Interpretive Summary: Water quality can often by degraded by sediments, nutrients (N – Nitrogen, P – Phosphorus), and pesticides originating on agricultural croplands. A variety of best management practices (BMPs) are available to crop producers to control and minimize transport of these pollutants into off-site water bodies. However, there is a growing concern that changing climate (increased rainfall, more intense storms, increasing temperatures, etc.) may degrade the performance of BMPs and put future water resources at more risk. In this research, we used a computer simulation model called SWAT (Soil and Water Assessment Tool) and sets of current and future estimates of climate conditions to determine how effective individual and combinations of BMPs are. The BMPs examined were no-tillage, vegetative filter strips, grassed waterways, blind inlets, and nutrient management. We found that for this particular location, no-till was the most effective individual practice for reducing pollutant losses now and into the future. We also found that combinations of BMPs were more effective at reducing multiple pollutant losses at the same time. This research impacts scientists, conservation agency personnel, extension service staff, farmers, and others involved in evaluating and recommending land management practices to reduce and control pollutant losses. Procedures developed and used in this computer simulation study could be followed and applied to other locations to assess the potential of climate changes there.
Technical Abstract: The Soil and Water Assessment Tool with downscaled weather data generated using the MarkSim weather file generator was used to evaluate the impact of long-term conservation practice implementation on runoff, sediment, atrazine, nitrogen (N) and phosphorus (P) losses in the AXL Watershed located in northeastern Indiana. As part of the Conservation Effects Assessment Project, evaluation of these conservation practices is required to provide insight on how their implementation is benefiting the environment. The results indicate that individual conservation practices were effective in reducing a particular pollutant load, but combined practices were more effective in reducing multiple pollutant loads simultaneously. Of the individual best management practices (BMPs) assessed, no-till was the most effective in reducing multiple pollutant loads (reduced surface runoff by an average of 25%, sediment by 46%, atrazine by 46%, total N by 9%, soluble P by 16%, and total P by 29%). When BMPs were combined, pollutant load reductions were increased significantly (at alpha = 0.05) for all pollutants, both under baseline and future climate scenarios. The reductions in runoff and pollutant loads for each decade of future climate ranged from 15% to 25% for surface runoff, 32% to 68% for sediment loss, 37% to 60% for atrazine loss, 5% to 13% for soluble N loss, 12% to 35% for total N loss, 9% to 41% for soluble P loss, and 33% to 60% for total P loss.