Several structural, treatment, and management approaches exist to minimize phosphorus (P) transport from agricultural landscapes (e.g., cover cropping and conservation tillage). However, many of these practices are designed to minimize particulate P transport and are not as effective in controlling dissolved P (DP) losses. Phosphorus removal structures employ a P sorption material (PSM) to trap DP from flowing water. These structures have been successful in treating surface runoff by utilizing aluminum (Al)-treated steel slag, but subsurface tile drainage has never been tested with this material. The goal of this study was to evaluate the performance and economics of a ditch-style P removal structure using Al-treated steel slag for treating agricultural subsurface drainage discharge. The structure treated subsurface drainage water from a 4.5 ha agricultural field with elevated soil test P levels. Overall, the structure removed approximately 27% and 50% of all DP and total P (TP) entering the structure, respectively (i.e., 2.4 and 9.4 kg DP and TP removal). After an initial period of strong DP removal, the discrete DP removal became highly variable. Flow-through analysis of slag samples showed that the slag used to construct the structure was coarser and less sorptive compared to the slag samples collected prior to construction that were used to design and size the structure. Results of this study highlight the importance of correctly designing the P removal structures using representative PSMs.
Bibliographical noteFunding Information:
Funding: Funding for this research was in part from USDA Natural Resources Conservation Service (NRCS) Mississippi River Basin Initiative (MRBI) and Conservation Effects Assessment Project (CEAP). This research is a contribution from the USDA Long-Term Agroecosystem Research (LTAR) network.
Funding for this research was in part from USDA Natural Resources Conservation Service (NRCS) Mississippi River Basin Initiative (MRBI) and Conservation Effects Assessment Project (CEAP). This research is a contribution from the USDA Long-Term Agroecosystem Research (LTAR) network. The authors would also like to acknowledge the support of Jed Stinner, Sara Henderson, and Katie Rumora in field installation and collection of measurement data and water samples. Eric Fischer, Marie Pollock, and many undergraduate students contributed to the laboratory analysis of water samples. The authors would also like to thank the cooperating farmers for allowing access to the farm and cooperation in implementing the project tasks. Asmita Murumkar provided editing comments on the manuscript drafts during internal reviews.
© 2020 by the authors.
- Algal bloom
- Case study
- Dissolved phosphorus
- Phosphorus sorption materials
- Phosphorus transport
- Subsurface drainage
- Tile drainage
- Water quality