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ARS Home » Plains Area » Temple, Texas » Grassland Soil and Water Research Laboratory » Research » Publications at this Location » Publication #319144
Title: Estimating the effects of agricultural conservation practices on phosphorus loads in the Mississippi-Atchafalaya River basin

Author
item SANTHI, C - Texas Agrilife Research
item White, Michael
item Arnold, Jeffrey
item NORFLEET, L - Natural Resources Conservation Service (NRCS, USDA)
item ATWOOD, J - Natural Resources Conservation Service (NRCS, USDA)
item KELLOGG, R - Natural Resources Conservation Service (NRCS, USDA)
item KANNAN, N - Tarleton State University
item WANG, X - Texas Agrilife Research
item DI LUZIO, M - Texas Agrilife Research
item WILLIAMS, J - Texas Agrilife Research
item GERIK, T - Texas Agrilife Research

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2014
Publication Date: 11/28/2014
Publication URL: http://handle.nal.usda.gov/10113/61275
Citation: Santhi, C., White, M.J., Arnold, J.G., Norfleet, L., Atwood, J., Kellogg, R., Kannan, N., Wang, X., Di Luzio, M., Williams, J.R., Gerik, T. 2014. Estimating the effects of agricultural conservation practices on phosphorus loads in the Mississippi-Atchafalaya River basin. Transactions of the ASABE. 57(5)1339-1357.

Interpretive Summary: Agricultural production in the Mississippi River Basin is important to the national economy and to water quality in the Gulf of Mexico. The Conservation Effects Assessment Project (CEAP) was initiated to determine the environmental impacts of USDA Conservation practices and was utilized in this study in the Mississippi River Basin. Results from the study indicate that current USDA conservation practices have reduced nitrogen loads to the Gulf of Mexico by 13-52% and total phosphorus loads by 22%. The CEAP modeling system was shown to be a useful tool for determining the impacts of conservation practices at large scales and in developing conservation policy.

Technical Abstract: Agriculture in the Mississippi-Atchafalaya River basin (MARB) is important in terms of both the national economy and the nutrients discharged to the basin and the Gulf of Mexico. Conservation practices are installed on cropland to reduce the nutrient losses. A recent study by the Conservation Effects Assessment Project (CEAP) determined the effects of agricultural conservation practices on water quality in the MARB. A modeling framework consisting of a farm-scale model (Agricultural Policy Environmental Extender, APEX), a watershed-scale model (Soil and Water Assessment Tool, SWAT), and databases was used. APEX was used to simulate the conservation practices on cropland and Conservation Reserve Program (CRP) land and assess the edge-of-field water quality benefits. The predicted flow and loads from APEX were input to SWAT, and SWAT was used to simulate the watershed processes and estimate the local and instream water quality benefits. The model was used for scenario assessment after calibration and validation for streamflow and loads. Recent studies indicate that phosphorus influences the formation of the hypoxic zone in the Gulf of Mexico. The major objectives of this article are to: (1) estimate and discuss the effects of currently existing and additional conservation practices on total phosphorus (TP) loads in the MARB, and (2) assess how TP loads discharged by the conservation scenarios can achieve the recommended annual P target for hypoxia reduction. Results indicated that current conservation practices on cropland have reduced TP losses to local waters by 13% to 52% in six basins within the MARB and reduced the TP load discharged to the Gulf of Mexico by 22%. Additional P load reduction is likely required to reach the annual P target for hypoxia reduction.