Salinity and sodicity of irrigated Solonetzic and Chernozemic soils in east-central Alberta

A 4-yr study was conducted on irrigated Solonetzic and Chernozemic soils in the Berry Creek Basin of east-central Alberta to assess changes in soil sa linity and sodicity during irrigated alfalfa production and to evaluate the suitability of Solonetzic soils for irrigation. Two of the study sites con sisted mainly of soils classified as Solodized Solonetz, with at least 70% in the Solonetzic order. Two chernozemic sites were almost exclusively Cher nozemic soils. A significant increase in soil salinity occurred in the A ho rizon at one solonetzic site and at both chernozemic sites and in the B hor izon of one chernozemic site. Mean electrical conductivity (ECe) in these h orizons for all irrigation treatments was less than or equal to 1 dS m(-1). Soil sodicity also increased significantly in the A horizon at one solonet zic site, and in the A and B horizons of both chernozemic sites. The mean s odium adsorption ratio (SAR) of the A horizon at this solonetzic site was 2 .9, 4.8, 4.4 and 5.0 for the control, low, medium and high irrigation treat ments, respectively. The SAR in the A horizon at the chernozemic sites was less than 2.6 for all the irrigation treatments. Increases in soil salinity and sodicity were attributed to the chemistry and amount of irrigation wat er used at each site. Salinization and sodification in addition to the chan ges associated with the quality and quantity of irrigation water were not e vident at any of the sites. The two-cut yield of alfalfa from the solonetzi c sites in the third year of growth was about 25% less than from the cherno zemic sites and was below the acceptable yield range for irrigated alfalfa in southern Alberta. Our results confirm existing land classification stand ards in Alberta that exclude solonetzic landscapes from irrigation developm ent where more than about 30% of the soils have an SAR value greater than 1 2 in any soil horizon within 1 m of the surface.