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

Abstract

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 salinity and sodicity during irrigated alfalfa production and to evaluate the suitability of Solonetzic soils for irrigation. Two of the study sites consisted mainly of soils classified as Solodized Solonetz, with at least 70% in the Solonetzic order. Two chernozemic sites were almost exclusively Chernozemic soils. A significant increase in soil salinity occurred in the A horizon at one solonetzic site and at both chernozemic sites and in the B horizon of one chernozemic site. Mean electrical conductivity (ECe) in these horizons 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 solonetzic site, and in the A and B horizons of both chernozemic sites. The mean sodium 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 treatments, 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 water used at each site. Salinization and sodification in addition to the changes associated with the quality and quantity of irrigation water were not evident at any of the sites. The two-cut yield of alfalfa from the solonetzic sites in the third year of growth was about 25% less than from the chernozemic sites and was below the acceptable yield range for irrigated alfalfa in southern Alberta. Our results confirm existing land classification standards in Alberta that exclude solonetzic landscapes from irrigation development where more than about 30% of the soils have an SAR value greater than 12 in any soil horizon within 1 m of the surface. Key words: Solonetzic soils, irrigation suitability, soil salinity, soil sodicity, irrigated alfalfa