Conditioning Effect of Different Absorbant Polymers on Physical and Chemical Properties of Sandy Soil

Abstract

Nowadays, the use of absorbant polymers (hydrogels) for soil conditioning is considered an effective way to solve the problems of water limitation of sandy soils for reclamation of newly desert areas. In this work, the physical and chemical properties of the sandy soil mixed with different concentrations of five types of hydrogels were studied. The used hydrogels were polyacrylic acid (Aquakeep, AKG); sodium polyacrylate (Aqurihop); vinyl alcohol sodium polyacrylate (Igata, IGG); cellulose (Jelfine, JFG); and starch (Was, WG). The used concentrations of each hydrogel were 0.05, 0.1, 0.2 and 0.4% of the soil weight. The results demonstrated that the maximum water absorption capacity differed greatly from hydrogel to another. AKG and WG had the highest water absorption capacity, while JFG was the lowest indicating that using of AKG and/or WG is the best for water conservation in sandy soils. Moreover, for all used hydrogels, the moisture content of the sandy soil increased with all applied pF values at concentrations of 0.05 or 0.1% hydrogel. A decrease in the bulk density and increase in total porosity of the soil was noticed with the increase of the hydrogel concentration. Soil infiltration rate and hydraulic conductivity were decreased due to the increase in water-holding capacity by conditioning the soils with the used hydrogels. Chemical properties were improved by conditioning the sandy soils with studied hydrogels. All hydrogels could lower the pH values but increase the cation exchange capacity (CEC) of the soil depending on the hydrogel concentration. Using high concentration (0.4) of each hydrogel, the soil pH was slightly lowered, while CEC and organic matter were increased noticeably with more available NPK content (nitrogen, phosphorus, potassium content) in the conditioned soils. From overall experiments, addition of WG, IGG, AKG to the sandy soil appear to be the best for retaining moisture at field capacity, which provides more available water to the plants and caused improvement of physical and chemical properties of the sandy soil.