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Volume 48, Issue 4 p. 959-965
Special Section: Agricultural Water Quality in Cold Environment

Contribution of Overland and Tile Flow to Runoff and Nutrient Losses from Vertisols in Manitoba, Canada

Vivekananthan Kokulan

Corresponding Author

Vivekananthan Kokulan

Dep. of Geography and Environmental Management, Univ. of Waterloo, Waterloo, ON, N2L 3G1 Canada

Corresponding author ([email protected]).Search for more papers by this author
M. L. Macrae

M. L. Macrae

Dep. of Geography and Environmental Management, Univ. of Waterloo, Waterloo, ON, N2L 3G1 Canada

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D. A. Lobb

D. A. Lobb

Dep. of Soil Science, Univ. of Manitoba, Winnipeg, MB, R3T 2N2 Canada

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G. A. Ali

G. A. Ali

Dep. of Geological Sciences, Univ. of Manitoba, Winnipeg, MB, R3T 2N2 Canada

School of Environmental Sciences, Univ. of Guelph, Guelph, ON, N1G 2W1 Canada

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First published: 01 July 2019
Citations: 23

Supplemental material is available online for this article.

Assigned to Associate Editor Jon Duncan.

Abstract

This study quantified the contributions of overland and tile flow to total runoff (sum of overland and tile flow) and nutrient losses in a Vertisolic soil in the Red River valley (Manitoba, Canada), a region with a cold climate where tile drainage is rapidly expanding. Most annual runoff occurred as overland flow (72–89%), during spring snowmelt and large spring and summer storms. Tile drains did not flow in early spring due to frozen ground. Although tiles flowed in late spring and summer (33–100% of event flow), this represented a small volume of annual runoff (10–25%), which is in stark contrast with what has been observed in other tile-drained landscapes. Median daily flow-weighted mean concentrations of soluble reactive P (SRP) and total P (TP) were significantly greater in overland flow than in tile flow (p < 0.001), but the reverse pattern was observed for NO3–N (p < 0.001). Overland flow was the primary export pathway for both P and NO3–N, accounting for >95% of annual SRP and TP and 50 to 60% of annual NO3–N losses. Data suggest that tile drains do not exacerbate P export from Vertisols in the Red River valley because they are decoupled from the surface by soil-ice during snowmelt, which is the primary time for P loss. However, NO3–N loading to downstream water bodies may be exacerbated by tiles, particularly during spring and summer storms after fertilizer application.

Core Ideas

  • Overland flow was the primary pathway for runoff and nutrient loss at field edge.
  • Most runoff and nutrient loss occurred during spring snowmelt and rain events.
  • Tile drains are unlikely to exacerbate P losses from Vertisolic soils.
  • Tile drains may enhance N loading in this region.