The relative effects of Na+ and K+ on soil structural stability due to application of some conditioners in sodic soils are not clearly defined by the existing literature. In this research, a completely randomized design experiment was performed to quantify the effect of some conditioners on physical properties in a loamy sodic soil. Five treatments included no conditioner as a control, urban solid waste compost (MC), Vermi-compose (VC), poultry manure (PM), and gypsum powder (G). The amount of each soil amendment was 10 ton/ha and each treatment consisted of 3 replications. The most important structural stability indicators including air capacity (AC), water dispersible clay (WDC), the slope of the retention curve at the inflection point (Sgi index), and mean weight diameter of aggregates (MWD) were measured. The results showed that compared with the control, soil conditioners improved soil structural stability indicators significantly (P < 0.05). Due to application of studied conditioners, the values of AC, WDC, Sgi index, and MWD increased. In addition, it was demonstrated that there was a negative and significant correlation between CROSS and SAR and structural stability indicators. By increasing SAR and Cation Ratio of Soil Structural Stability WDC, Sgi index, AC, and MWD values were decreased and as a result of these processes and improvement the physical condition of seedbeds, the dry weight of maize was increased.

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