Impact of Irrigation with Poor Quality Groundwater on Saskatchewan Soils

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Two irrigation sites near the rural communities of Donavon and Watrous, Saskatchewan were evaluated to determine the impact of irrigation with poor quality groundwater on soil and near-surface aquifer salinity. Prior to experimentation, the two sites had been irrigated with saline groundwater for six and seven years, respectively. Experimental work comprised both laboratory and field analysis. Laboratory experiments included monitoring chemical changes within the soil column profiles following application of fresh water and simulated aquifer water. The results indicated that although the level of chloride in the effluent initially increased, an equilibrium value was achieved following continued saline water application. In triplicate trials the rate of chloride ion removal was consistently lower than that predicted with a complete mixing leaching model, likely due to incomplete mixing of the applied and residual soil water. Field experiments included soil salinity surveys using a non-contacting electromagnetic terrain conductivity meter (EM 38) and saturated paste extracts (SPE) at the two groundwater irrigation sites to monitor salt accumulation in the soils between 1982 and 1988. Initial surveys indicated that salinity levels at the two sites were similar with higher salinity in the upper layers of soil, both inside and outside the irrigated circles. With the exception of the results from the deepest soil layer in which the SPE salinity exceeded EM 38 readings, no significant differences were observed between salinity measured from SPE and those computed from EM 38 readings at either the Donavon or Watrous site.