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Journal of Environmental Quality Abstract - Surface Water Quality

Reducing Nitrate Loss in Tile Drainage Water with Cover Crops and Water-Table Management Systems


This article in JEQ

  1. Vol. 43 No. 2, p. 587-598
    Received: Dec 20, 2012
    Published: June 23, 2014

    * Corresponding author(s): craig.drury@agr.gc.ca
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  1. C. F. Drury *,
  2. C. S. Tan,
  3. T. W. Welacky,
  4. W. D. Reynolds,
  5. T. Q. Zhang,
  6. T. O. Oloya,
  7. N. B. McLaughlin and
  8. J. D. Gaynor
  1. (deceased), Greenhouse and Processing Crops Research Centre, Agriculture and Agri-Food Canada, Harrow, ON, Canada N0R1G0


Nitrate lost from agricultural soils is an economic cost to producers, an environmental concern when it enters rivers and lakes, and a health risk when it enters wells and aquifers used for drinking water. Planting a winter wheat cover crop (CC) and/or use of controlled tile drainage–subirrigation (CDS) may reduce losses of nitrate (NO3) relative to no cover crop (NCC) and/or traditional unrestricted tile drainage (UTD). A 6-yr (1999–2005) corn–soybean study was conducted to determine the effectiveness of CC+CDS, CC+UTD, NCC+CDS, and NCC+UTD treatments for reducing NO3 loss. Flow volume and NO3 concentration in surface runoff and tile drainage were measured continuously, and CC reduced the 5-yr flow-weighted mean (FWM) NO3 concentration in tile drainage water by 21 to 38% and cumulative NO3 loss by 14 to 16% relative to NCC. Controlled tile drainage–subirrigation reduced FWM NO3 concentration by 15 to 33% and cumulative NO3 loss by 38 to 39% relative to UTD. When CC and CDS were combined, 5-yr cumulative FWM NO3 concentrations and loss in tile drainage were decreased by 47% (from 9.45 to 4.99 mg N L−1 and from 102 to 53.6 kg N ha−1) relative to NCC+UTD. The reductions in runoff and concomitant increases in tile drainage under CC occurred primarily because of increases in near-surface soil hydraulic conductivity. Cover crops increased corn grain yields by 4 to 7% in 2004 increased 3-yr average soybean yields by 8 to 15%, whereas CDS did not affect corn or soybean yields over the 6 yr. The combined use of a cover crop and water-table management system was highly effective for reducing NO3 loss from cool, humid agricultural soils.

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