Author
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Tomer, Mark |
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Submitted to: Journal of Soil and Water Conservation
Publication Type: Other Publication Acceptance Date: 10/6/2017 Publication Date: 1/3/2018 Citation: Tomer, M.D. 2018. A twice-paired watershed experimental design to assess stacked practices through field-edge monitoring. Journal of Soil and Water Conservation. 73(1):58-61. https://doi.org/10.2489/jswc.73.1.58. DOI: https://doi.org/10.2489/jswc.73.1.58 Interpretive Summary: To improve our ability to reduce nutrient losses from agricultural lands to receiving waters, comprehensive approaches that employ a variety of conservation practices placed within and below field edges will be needed. There is a need to obtain experimental data to better understand how conservation practices can be combined in synergistic ways to meet water quality goals. This editorial proposes a twice-paired watershed experimental design, in which replicate edge-of-field practices are installed below two similar fields at the beginning of the calibration period in a paired watershed experiment. After calibration, a conservation treatment is then applied within one of the two fields and the treatment period monitoring is undertaken. Monitoring results could be used to evaluate both (in-field and edge-of-field) practices, obtain data to determine how the two practices interact, and what mechanisms may be involved in creating the interaction. The design requires four monitoring points but answers three question about two practices, which is a better “knowledge return” on investment compared to single practice evaluations which require two monitoring points but can only answer one question about a single practice. Example experimental layouts for several combined treatments are illustrated and described. The data obtained could further be used to validate how well watershed models can simulate the use of combined conservation practices for water quality improvement. This information is of interest to scientists working on water quality improvement in agricultural watersheds, watershed modelers, and agricultural-environmental research funding entities. Technical Abstract: To improve our ability to reduce nutrient losses from agricultural lands to receiving waters, comprehensive approaches that employ a variety of conservation practices placed within and below field edges will be needed. There is a need to obtain experimental data to better understand how conservation practices can be combined in synergistic ways to meet water quality goals. This editorial proposes a twice-paired watershed experimental design, in which replicate edge-of-field practices are installed below two similar fields at the beginning of the calibration period in a paired watershed experiment. After calibration, a conservation treatment is then applied within one of the two fields and the treatment period monitoring is undertaken. Monitoring results could be used to evaluate both (in-field and edge-of-field) practices, obtain data to determine how the two practices interact, and what mechanisms may be involved in creating the interaction. The design requires four monitoring points but answers three question about two practices, which is a better “knowledge return” on investment compared to single practice evaluations which require two monitoring points but can only answer one question about a single practice. Example experimental layouts for several combined treatments are illustrated and described. The data obtained could further be used to validate how well watershed models can simulate the use of combined conservation practices for water quality improvement. |
