the effects of soil conditioners on water retention content at different matric suctions in a saline-sodic soil

application of soil conditioners for remediation of saline- sodic soils is one of the common methods for improving soil properties in arid and semi-arid regions. in order to study the effect of soil conditioners on retention of soil moisture content, an experiment was carried out based on randomized complete block design with three replications in a saline-sodic sandy clay loam soil. the treatments of this research were consisted of control (b), 10 t.ha-1 gypsum powder (g), 10 t.ha-1 municipal compost (c), 0.05, 0.1, and 0.2% of vinylalcoholacrylic acid super absorbent (s1, s2 and s3), and mixtures of different levels of absorbent with compost, and or gypsum powder. after four months, gravimetric water contents in each treatment were measured at nine matric suctions, then available water content (awc) was calculated. the results showed that experimental treatments incresed water content in all matric suctions significantly (p≤0.05). the amounts of soil moisture in s1 treatment at 0 (θs) and 5 bar matric suctions were 90.67 and 94% more than b treatment, respectively, which they were the highest contents among experimental treatments. at field capacity (0.3 bar suction), cs1, s1 and cs2 treatments had the most effect on soil moisture retention, and the amounts of soil moisture in these treatments were about 73% higher than of b treatment. also, at permanent wilting point (pwp) s1 and cs3 treatments increased soil moisture by 1.6 and 1.42 times more than b treatment. in addition, when mixture of 10 t.ha-1 compost, 0.2% of absorbent was applied to soil, the highest amounts of awc was obtained and it was 63% more than of b treatment. in addition, application of soil conditioner increased air capacity significantly up to critical limit (0.10 m3 m-3). according to the results of this study it can be concluded the mixture of super absorbent in combination with gypsum powder is a suitable solution for retaining more soil moisture content and reducing the evaporation in arid and semi arid area.