| چکیده انگلیسی مقاله |
Soil salinization is an important aspects of land degradation, especially in arid and semi-arid regions. Saline and sodic soils have hyperirritability to erosion in physically, chemically and biologically factors. From the watershed management point of view, salinization has an adverse consequence such as erodibility, production of fine-grained sediment, reduction of infiltration, increased runoff and inhibition of plant growth in these areas. Therefore, modification of saline and sodic soils and modification of the effects of salinity using soil modifiers are considered. In this study, the effect of different treatments of gypsum particle size on physicochemical properties of saline and sodic soils was investigated. Also, the amount of water required for leaching saline and sodic soils and the quality of outflow drains water under the influence of gypsum treatment were investigated. This study was conducted in the form of a greenhouse experiment in a completely randomized block design. Experimental treatments include gypsum with different amount (5 and 50 g of gypsum per kg of soil), gypsum with different particle diameters (60, 35, 10 and 5 mesh equal to 0.25, 0.5, 2 and 4 mm), and the control. Treatments were applied at two depths of 0-15 and 15-30 cm with three replications. The cylindrical columns made of polyethylene (height 40 and diameter 35 cm) with drainage installed in the deep part were used for experiments. The defined columns were filled with saline and sodium soil (ESP = 21). The soil columns, were washed six times after complete saturation. At each stage of leaching, the effluents from the drain columns were collected. At the end of this experiment, soil samples were collected from two depths (0-15 and -30. 15 cm) of leached soil. Some physico-chemical soil properties include calcium, magnesium, sodium, EC, SAR and ESP were measured and statistically analysed. In the second stage, saline and sodium soils were treated with the optimal amounts of gypsum determined in the first stage. After each leaching, soil properties were measured at two depths. Based on the results, the best amount of gypsum for saline and sodic soils treatment was 7.5 g of gypsum per kg of soil, equivalent to 33.7 ton. ha-1. The best gypsum particle diameter was 35 mesh (0.5 mm). Finally, the results of this study showed that using gypsum modifier should reduce the amount of water required for leaching and modification of saline and sodic soils. |
