Correlations between Constituents in Irrigation Waters and Irrigated Soils in Kansas

Abstract

AbstractSoil and water from 26 sites from north‐central and southwestern Kansas were studied to determine if knowledge of the chemical composition of irrigation water could be used to predict salt and Na accumulation in soil. Samples were collected in the summer of 1958 and 1959.Mean exchangeable Na percentage in irrigated soils can be predicted with reasonable accuracy from constituents in irrigation water using Gapon's equation, soluble Na percentage, or the Na adsorption ratio as the basis for estimation. Exchangeable Na percentage can be estimated with an accuracy of ± 1.8 at the 0.90 probability level for 25 out of the 26 soils.Correlation between conductivity of soil saturation extracts and that of irrigation water was 0.98 when observations were restricted to soils that (a) increased in total salt content upon irrigation and (b) in which conductivity of the saturation extract exceeded that of irrigation water. Maximum irrigation water electrical conductivity used on such soils was 2.28 mmho per cm. For this value, soil saturation extract electrical conductivity could be predicted with an accuracy of ± 0.54 mmhos per cm. at the 0.90 probability level.Electrical conductivity of soil saturation extracts varied from 0.4 to 4.7 mmho per cm. at 25° C. Mean exchangeable Na percentage ranged from 0.1 to 6.2. Irrigation water ranged in conductivity from 0.3 to 4.9 mmho per cm. at 25° C.