A new type of soil created by engineers at the University of Texas at Austin can draw water from the air and distribute it to plants. This could lead to the expansion of the map of arable land around the world to previously non-agricultural places and reduce water use in dry-area agriculture.
As published in ACS Materials Letters, the team's atmospheric water irrigation system uses ultra-moisture-absorbing gels to capture water from the air.
When the soil is heated to a certain temperature, the gels release water, making it available to plants. When the soil distributes water, part of it returns to the air, increasing humidity and facilitating the continuation of the harvesting cycle.
"Enabling self-planting in areas where irrigation and energy systems are difficult to build is critical to freeing crop cultivation from a complex water supply chain where resources are becoming increasingly scarce," said Guihua Yu, assistant professor of materials science at the Walker division.
Each gram of soil can draw approximately 3-4 grams of water. Depending on the crops, about 0.1 to 1 kilogram of soil can provide enough water to irrigate about a square meter of farmland. The gels in the soil draw water from the air during the colder and humid periods of the night. During the day, solar heat activates water-containing gels to release their contents into the soil.
The team conducted experiments on the roof of the Cockrell School Engineering Education Center building in UT Austin to test the soil. They found that hydrogel soils are able to retain water better than sandy soils found in dry areas, and require much less water to grow plants.
During a four-week trial, the team found that its soil retained about 40% of the amount of water it started with. In contrary, only 20% of the water remains in the sandy soil after just one week.
"Most soils are good enough to support plant growth," said Phi Zhao, a postdoctoral researcher at the Yu Research Group who led the study with Xingyi Zhou and Panpan Zhang.
"Water is the main obstacle, so we wanted to develop soil that could draw water from the surrounding air."
Water withdrawal soil is the first major technology application the Yu's research group has been working on for more than two years.
Last year, the team developed the ability to use hybrid polymer gels that work, such as 'super sponges' to extract, clean and quickly release large amounts of water from surrounding air using solar energy.
Researchers envision many other applications of technology, which can be used to cool solar panels and data centers.
Source: https://phys.org
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