Wax-coated sand keeps soil wet longer and improves crop

Dry, hot regions are difficult places to grow plants because the soil dries out quickly.

Previous studies have shown that ground cover barriers, such as plastic sheets and engineered nanomaterials, can slow evaporation and enhance plant growth and crop yields. However, both could leach unwanted compounds into the soil with unknown long-term impacts.

Researchers dissolved purified paraffin in hexane and poured silica sand into the mixture. As the solvent evaporated, a 20-nm-thick coating of wax was left behind on the grains. When the team applied the wax-coated sand in a thin layer on an open field in, it decreased the loss of soil moisture up to 50–80%.

Field trials revealed that tomato, barley and wheat plants mulched with the new material produced substantially more fruit and grain than those grown in uncovered soil. In addition, the microbial community around the plants' roots and in the soil wasn't negatively impacted by the waxy mulch, which could have acted as a food source for some of the microbes.

This simple nature-inspired technology could make water use more efficient in arid regions.