A new sort of soil created by engineers at the University of Texas at Austin can pull water from the air and distribute it to plants, potentially expanding the map of farmable land round the globe to previously inhospitable places & reducing-water use in agriculture at a time of growing droughts.
As published in ACS Materials Letters, the team’s atmospheric water irrigation system uses super moisture absorbent gels to capture water from air. When the soil is heated to a particular temperature, the gels release the water, making it available to plants. When the soil distributes water, a few of it goes back to the air, increasing humidity and making it easier to continue the harvesting cycle.
“Enabling free standing agriculture in areas where it’s hard to create up irrigation & power systems is crucial to liberating crop farming from the complex water system chain as resources become increasingly scarce” said Guihua Yu, professor of materials science in the Walker Department of engineering.
Each gram of soil can extract approx. 3-4 grams of water. Depending on crops, approx. 0.1 – 1 Kg of the soil can provide enough water to irrigate a few square metre of farmland.
The gels in the soil pull water out of the air during cooler– more humid periods in the dark. Solar heat during the day activates the water containing gels to release their contents into soil.
The team ran experiments on the roof of the Cockrell School’s Engineering Teaching Center building at UT Austin to check the soil. They found that the hydrogel soil was ready to retain water better than sandy soils found in dry areas and it needed far less-water to grow plants.
During a 4 week experiment, the team found that soil retained approx. 40% of the water quantity it started with. In contrast, the sandy soil had only 20% of its water left after only one week.
In another experiment, the team planted radishes in both sorts of soil. The radishes in the hydrogel soil all survived a 14 day period with none irrigation beyond an initial round to form sure the plants took hold. Radishes in the sandy soil were irrigated several times during the primary 4 days of the experiment. None of the radishes in the sandy soil survived more than 2 days after the initial irrigation period.
“Most soil is sweet enough to support the expansion of plants” said Fei Zhao, a postdoctoral researcher in Yu’s research group who led the study with Xingyi Zhou & Panpan Zhang. “It’s the water that’s the most limitation, in order that is why we wanted to develop a soil which will harvest water from ambient air.”
The water-harvesting soil is the first greatest application of technology that Yu’s group has been performing on for quite 2 years. Last year, the team developed the capability to use gel polymer hybrid-materials that work like “super sponges” extracting large amounts of water from the ambient air, cleaning it & quickly releasing it using solar energy.
The researchers envision various other applications of the technology. It could potentially be used for cooling solar panels & data centers. It could expand access to drinking water, either through individual systems for households or larger systems for giant groups like workers or soldiers.