1. Department of Civil and Environmental Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, USA
2. College of the Environment and Ecology, Xiamen University, Xiamen, Fujian 361102, China
3. Conservation & Environment Branch, Economic Research Service, USDA, Kansas City, Missouri 64105, USA
4. Department of Agricultural and Consumer Economics, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, USA
5. Department of Agricultural and Biological Engineering, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, USA
6. Department of Natural Resources and Environmental Sciences, University of Illinois at Urbana−Champaign, Urbana, Illinois 61801, USA
7. Agricultural Watershed Institute, Decatur, Illinois 62521, USA