The influence of sugarcane mulch on sand dune stabilization in Khuzestan, the southwest of Iran

Over the past 50 years, oil mulching has been a common technique for sand dune stabilization in the southwest of Iran (Khuzestan province). However, concerns over the release of heavy metals from oil mulching have led to the search for alternative mulches that are capable of stabilizing sand dunes without environmental hazards. This study investigates the feasibility of using sugarcane residues for producing environment-friendly mulches. Dunder, Press Mud, and clay soil from the surrounding area near the sand dunes were used to make sugarcane mulches for comparison with the traditional oil mulch. A sand dune was selected as a sample bed for applying the mulch. To select the proper ingredients and treatments, Dunder, Press Mud, and clay soil were mixed with water by a trial-and-error method. The selected batch mix was then used to make the desired mulch and sprayed on a sand dune bed. Shear strength of surface soil (SSS), penetration resistance (PR), soil surface shear resistance (SSR), and erodibility of selected treatments were measured by the shear torvane, hand penetrometer, Zhang’s surface shear device, and the wind tunnel. The treatments were arranged in a factorial experiment within a completely random design with the factors including mulch type (seven sugarcane mulches and one traditional oil mulch), thickness (1 or 2 layers), and rainfall (rain and no rain). The results indicate that SSS and PR increased with mulch thickness; the average values of SSS and PR obtained with the two-layer treatments were 1.27‒1.33 and 1.13‒1.15 times as great as the single-layer treatments. Increasing fraction of sugarcane residues significantly increased the SSS and PR. Higher concentrations of organic matter, CaCO3, and electrolyte in the sugarcane mulches may have helped the bonding of soil particles and increased the SSS and PR. However, the oil mulch had the lowest SSS but the highest PR. This might be due to the lower viscosity of oil mulch that allows it to penetrate sand dunes more easily than sugarcane mulches do.