Continuous and Surge Irrigation Effects on Hydraulic Parameters and Water Quality

Abstract

Abstract Limited information exists on comparing the effect of continuous and surge irrigation on hydraulic parameters and water quality under border-strip irrigation in the Canadian Prairies. A site on a clay loam soil in southern Alberta was used to compare these two irrigation methods (three replicates) on plots seeded to barley (Hordeum vulgare) in 1996 and 1997. Irrigation was conducted on border-strip plots in July and August of each year. Irrigation hydraulic parameters, soil water content, chloride and sediment in runoff, chloride in suction lysimeters, soil and shallow groundwater, and the water table level were measured before and after irrigation. Surge irrigation significantly (P ≤ 0.10) reduced the following hydraulic parameters compared to continuous irrigation: irrigation water applied (129–304%), total surface runoff (93–257%), maximum outflow rate (25–146%), advance time to the end of the field (214–273%), total infiltration depth of water (135–390%), and total irrigation time. However, irrigation treatment had no significant effect on surface runoff and infiltration depth of water when expressed as a percentage of the total amount of irrigation water applied. Surge had little or no effect on the concentration, flow-weighted mean concentration (FWMC) and mass loss of chloride and sediment in runoff. The exceptions were in July 1996, where mass loss of chloride was 180% lower under surge; and in August 1997, where the concentration of chloride was 44% lower under surge. Irrigation method had little or no significant effect on the soil water content, concentration of chloride in suction lysimeters and groundwater, the total mass of chloride in the soil profile, and the water table level. However, there was a trend towards lower chloride values under continuous than surge irrigation in the lysimeters and soil, suggesting a potential for greater leaching under the former method. Although surge irrigation had little or no positive effect on water quality compared to continuous irrigation, surge is still the preferred irrigation method because of its many improvements in hydraulic parameters.