To prevent water from evaporating from the soil, farmers usually cover the ground around the plants with polyethylene. But there will soon be a more environmentally friendly alternative, in the form of sand coated with soybean oil. When most people hear the word & quot; mulch, they think of organic materials such as tree bark or dead leaves. However, the frequently used agricultural plastic cloth is also a form of mulch. In addition to helping to keep the soil moist, it can also reduce the growth of weeds, prevent soil erosion, and increase soil temperature by creating a ground-based greenhouse effect. However, like other plastic products, the production process of sheet metal is not a very environmental protection process. In addition, once the plastic cover cracks and breaks, it is usually only removed and dumped in the dump. More importantly, its tiny particles may remain in the soil or even enter the harvested crops. < / P > < p > led by Associate Professor Michael Nicholl, scientists at the University of Nevada in Las Vegas began to develop a more environmentally friendly alternative that would provide similar water retention properties. < / P > < p > they first combine equal amounts of sand with soybean oil, heat the mixture for about an hour, and then let it cool. This process causes the oil to partially polymerize, forming a coating around each grain of sand. Finally, the coated sand is washed in water and allowed to dry to remove excess oil. < / P > < p > in laboratory tests, a layer of oil coated sand is placed on the various types of soil contained in the vertical part of the PVC pipe, and then the soil is soaked with water. It is observed that water can easily flow into the soil through the sand. The challenge, however, is how to keep the liquid there. < / P > < p > & quot; when water is applied to the surface of the soil (rain, irrigation), some of the water seeps down under capillary and gravity, explains Nicholl. &After the application of water, the soil began to dry from the top down. As the top surface becomes drier, capillary action causes water to rise in deeper and wetter soil, where it evaporates on the surface and enters the atmosphere directly. &Due to its hydrophobic (water repellent) properties, the oil coating helps to prevent this – even though water still travels up through the soil, it is basically trapped by sand, which in turn prevents it from evaporating. All in all, the study found that compared with the control sample of bare soil, the evaporation water loss of sand covered soil was as high as 96%. < / P > < p > & quot; these findings suggest that sand in oil may be developed as a sustainable alternative to plastic film mulch, Nicholl said. Global Tech