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Journal of Environmental Quality Abstract - Special Sections: Environmental Standards for Agricultural Watersheds

Using the Soil and Water Assessment Tool to Estimate Achievable Water Quality Targets through Implementation of Beneficial Management Practices in an Agricultural Watershed


This article in JEQ

  1. Vol. 41 No. 1, p. 64-72
    Received: June 2, 2010

    * Corresponding author(s): glenn.benoy@ec.gc.ca
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  1. Qi Yanga,
  2. Glenn A. Benoy *b,
  3. Thien Lien Chowc,
  4. Jean-Louis Daigled,
  5. Charles P.-A. Bourquea and
  6. Fan-Rui Menga
  1. a Faculty of Forestry and Environmental Management at the Univ. of New Brunswick, 28 Dineen Dr., Fredericton, NB, E3B 6C2, Canada
    b Environment Canada and Agriculture & Agri-Food Canada, Potato Research Centre, 850 Lincoln Rd., Fredericton, NB, E3B 4Z7, Canada
    c Potato Research Centre, Agriculture and Agri-Food Canada, 850 Lincoln Rd., Fredericton, NB, E3B 4Z7, Canada
    d Eastern Canada Soil and Water Conservation Centre, 1010, ch. de l’Église, Saint-André (Grand Falls), NB, E3Y 2X9, Canada. Assigned to Associate Editor Joseph Culp


Runoff from crop production in agricultural watersheds can cause widespread soil loss and degradation of surface water quality. Beneficial management practices (BMPs) for soil conservation are often implemented as remedial measures because BMPs can reduce soil erosion and improve water quality. However, the efficacy of BMPs may be unknown because it can be affected by many factors, such as farming practices, land-use, soil type, topography, and climatic conditions. As such, it is difficult to estimate the impacts of BMPs on water quality through field experiments alone. In this research, the Soil and Water Assessment Tool was used to estimate achievable performance targets of water quality indicators (sediment and soluble P loadings) after implementation of combinations of selected BMPs in the Black Brook Watershed in northwestern New Brunswick, Canada. Four commonly used BMPs (flow diversion terraces [FDTs], fertilizer reductions, tillage methods, and crop rotations), were considered individually and in different combinations. At the watershed level, the best achievable sediment loading was 1.9 t ha−1 yr−1 (89% reduction compared with default scenario), with a BMP combination of crop rotation, FDT, and no-till. The best achievable soluble P loading was 0.5 kg ha−1 yr−1 (62% reduction), with a BMP combination of crop rotation and FDT and fertilizer reduction. Targets estimated through nonpoint source water quality modeling can be used to evaluate BMP implementation initiatives and provide milestones for the rehabilitation of streams and rivers in agricultural regions.

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