Cation ratio of soil structural stability (CROSS) was used to evaluate the effects of potassium to calcium and magnesium ratio in irrigation water on soil properties of a sandy loam. For this purpose, a research was performed as a completely randomized design in undisturbed soil columns. Experimental factors were salinity (4 and 8 dS m-1) and CROSS of irrigation water (10, 15, 20 and 25). After 16 weeks, water dispersible clay (DC), saturated hydraulic conductivity (Ks), slope of retention curve at inflection point (S index), moisture content at field capacity (FC), permanent wilting point (PWP) and plant available water content (PAWC) were measured. The results showed that potassium ions in irrigation water significantly decreased DC, Ks, PAWC, and S index. The effect of potassium on soil physical properties depended on the total concentration of solutes. According to the results, it is suggested that the effects of potassium for assessing the soil structure should be considered.

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