Study of the effect of micro silica (Silica fume) as mulch on the soil losses of sand dunes

Wind erosion and sand dune movement as one of the most important reasons for desertification and land degradation in arid and semiarid areas, incorporates significantly in soil and natural resources damages, air pollution, health threat and socio-economic disturbances. Stabilization of sand dunes is therefore very important. One of the fundamental methods to control wind erosion and to stabilize sand dunes is the use of mulches on the soil surface. Providing a simple method using cheap materials for preparing a durable mulch in order to decrease soil losses is of high importance. Recently the use of industrial cheap and secure wastes as mulches are attracting more attention. The present study was conducted with the aim of investigating the effect of micro silica slurry as a byproduct in the manufacture of silicon or ferrosilicon alloy, on soil losses of sand dunes. Therefore, an experiment was carried out in factorial conducted as a completely randomized design at 3 replicates. Wind erosion meter was used to measure the soil losses. For preparing the treatments, trays with the sizes of 100 cm (length) × 30 cm (width) × 2 cm (depth) were filled with sand samples and their surfaces were level. Filled trays with sands were used for mulching. Micro silica slurry was sprayed over trays in 4 coverage percentages (25%, 50%, 75% and 100%), two thicknesses (one and two- layer) and two times (7 and 60 days). Sand trays were then weighed and exposed to a wind speed of 15 ms-1 at the height of 20 cm for 20 minutes (similar to the intensive wind flows of the studied area). Trays were weighed again and the amount of eroded materials were determined according to the weight differences of trays. Data were analyzed using MSTAT and EXEL software. Results showed that soil losses decreased significantly (P ≤ 0.01) with the increase in coverage percentage and thickness of micro silica slurry. Soil losses decreased more than 2 times at the micro silica slurry coverage surface of 100 percent in comparison with the coverage surface of 25 percent and soil losses decreased 55.3 % in treatments containing two layers of micro silica slurry in comparison with one layer treatments. The 50 percent micro silica slurry with the coverage percentage of 100% and tow layer thickness represented the best results in decreasing soil losses. Despite the significant effect of micro silica slurry mulch on soil losses decrease, its ability decreases with time. But as the soil losses are low in treatments containing two layers, it seems that more soil losses can be controlled by increasing the mulch thickness