A new type of self-watering soil made by engineers at The University of Texas in Austin can pull water out of the atmosphere and disperse it to plants, potentially expanding the map of farmable land round the world to formerly inhospitable places and reducing water use in agriculture at a time of developing droughts.
Water irrigation system employs super-moisture-absorbent gels to capture water from the air. When the self-watering soil is heated to a particular temperature, the gels discharge the water, making it available to crops. After the soil distributes water, some of it goes back to the air, increasing humidity and making it much easier to continue the harvesting cycle.
“Enabling free-standing agriculture in areas where it’s hard to build up irrigation and power systems is crucial to liberating crop farming from the complex water supply chain as resources become increasingly scarce,” said Guihua Yu, associate professor of materials science in the Walker Department of Mechanical Engineering.
Each gram of self-watering soil can extract roughly 3-4 g of water. Depending on the crops, approximately 0.1 to 1 kilogram of that soil can provide enough water to irrigate about a square meter of farmland.
The gels from the self-watering soil pull water from the atmosphere during cooler, longer humid periods at night. Solar heat during the day activates the water-containing gels to release their contents into dirt.
The team conducted experiments on the roof of the Cockrell School’s Engineering Teaching Center building at UT Austin to test the soil. They revealed that the hydrogel soil was able to keep water better than sandy soils found in arid places, and it needed far less water to grow crops.
During a four-week experiment, the group found that its self-watering soil retained approximately 40% of the water quantity it began with. In contrast, the sandy soil had only 20% of its own water left after just 1 week.
In another experiment, the group planted radishes in both types of soil. The radishes in the self-watering soil all endured a 14-day period without any irrigation beyond an initial round to guarantee that the plants took hold. Radishes in the sandy soil were irrigated a few times during the first four days of this experiment. Not one of the radishes from the sandy soil survived more than two days following the initial irrigation period.
“Most soil is good enough to support the growth of plants,” said Fei Zhao, a postdoctoral researcher in Yu’s research group who led the study with Xingyi Zhou and Panpan Zhang. “It’s the water that is the main limitation, so that is why we wanted to develop a soil that can harvest water from the ambient air.”
The water-harvesting soil is your first major application of technologies that Yu’s group was working on for more than a couple of years. This past year, the group developed the capability to use gel-polymer hybrid substances that work like “super sponges,” extracting large quantities of water in the ambient atmosphere, cleaning it and quickly releasing it with solar power.
The researchers envision several other programs of this self-watering soil technology. It could possibly be used for cooling solar panels and data centers. It could expand accessibility to drinking water, possibly through individual systems for families or bigger systems for large groups such as workers or soldiers.
Related Journal Article: https://pubs.acs.org/doi/10.1021/acsmaterialslett.0c00439