Strategic targeting of cropland management using watershed modeling

摘要

Pushpa Tuppad1, Kyle R. Douglas-Mankin2, Kent A. McVay3(1. Texas AgriLife Research, 1500 Research Parkway, Suite B223, Texas A&M University, College Station, TX 77843, USA;2. Department of Biological & Agricultural Engineering, Kansas State University, Manhattan, KS 66506, USA;3. Railroad Highway, Southern Agricultural Research Center, Huntley, MT 59037, USA)?Abstract: Effective water-quality protection should target Best Management Practices (BMPs) on watershed areas that contribute most to water-quality impairment instead of the typical voluntary implementation of practices, which may not be better than a random distribution of BMPs within a watershed. This paper demonstrates a strategic approach for targeting watershed areas to maximize water-quality benefits from BMP implementation. Almost half of the Smoky Hill River Watershed, Kansas, USA is cropland, a major sediment and nutrient source. The impacts of reduced tillage, edge-of-field vegetative filter strips, and contoured-terraced practices on erosion and nutrient loads both overland and at the watershed outlet were evaluated using either random or targeted implementation, based on simulated average subbasin erosion rate. The targeted approach was more effective in reducing sediment and nutrients, both at subbasin and watershed levels. Annual average overland pollutant load reductions of 10% required BMP adoption on less than half the land area with targeted versus random placement. The benefits of targeting were greater for initial increments of BMP adoption and decreased as implementation area increased.