Submitted to: Ecological Applications
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/30/2009
Publication Date: 9/15/2010
Citation: Rabotyagov, S., Campbell, T., Jha, M., Gassman, P.W., Arnold, J.G., Kurkalova, L., Secchi, S., Feng, H., Kling, C.L. 2010. Least-cost control of agricultural nutrient contributions to the Gulf of Mexico hypoxic zone. Ecological Applications. 20(6):1542-1555. Interpretive Summary: In recent years, a hypoxic or dead zone has been found in the Gulf of Mexico. The size of this hypoxic zone has been related to nitrogen and phosphorus loadings from agricultural fields in the Upper Mississippi river basin that flow down the Mississippi river into the Gulf. In this study, we combined a watershed model with optimization models and cost data to determine the least cost land management options while reducing nutrient loading into the Gulf of Mexico. The cost of reducing nitrogen loadings by 30 percent was estimated to cost $1.4 billion per year. The decision tool developed in this study can also be used by policy makers to determine trade offs between cost and nutrient reductions to the Gulf.
Technical Abstract: In 2007, the hypoxic zone in the Gulf of Mexico, measuring 20,720 km**2, was one of the two largest reported since measurement of the zone began in 1985. The extent of the hypoxic zone is related to nitrogen and phosphorous loadings originating on agricultural fields in the upper Midwest. This study combines the tools of evolutionary computation with a water quality model and cost data to develop a trade-off frontier for the Upper Mississippi River Basin specifying the least cost of achieving nutrient reductions and the location of the agricultural conservation practices needed. The frontier allows policymakers and stakeholders to explicitly see the tradeoffs between cost and nutrient reductions. For example, the cost of reducing annual nitrate-N loadings by 30 percent is estimated to be US$1.4 billion/year, with a concomitant 36 percent reduction in P and the cost of reducing annual P loadings by 30 percent is estimated to be US$370 million/year, with a concomitant 9 percent reduction in nitrate-N.