Super moisture-absorbent gels could revolutionize arid soil irrigation

Tamanrasset, Algérie, désert du Sahara.

Tamanrasset, Algeria, Sahara desert

How can you produce water where there is none? Researchers from the University of Texas in Austin have just made a discovery that could open up the planet’s driest soils to agriculture. 

They have produced super moisture-absorbent gels (SMAGs) with a hygroscopic polymer that captures water vapor suspended in the atmosphere and turns it into water for plants. Their experiments have shown that these gels mixed with dry, sandy soils increased water availability for sufficiently long periods to grow vegetables. 

SMAGs have been known for a long time, but this is the first time that their efficacy has been tested on arid soils. In dry regions, humidity levels rise at night, which is cooler than daytime. This potential water resource need only be recovered and stored in the soil. 

These gels are also heat-sensitive: when the temperature rises during the day, the stored moisture is released directly into the soil in the form of water. Some of this moisture evaporates to humidify the plant’s surface, an added advantage against dry air. 

40% drylands on Earth

The researchers compared radishes grown in plots with ordinary soil with those grown in gel-enriched soil. In the first, the seeds germinated but died after six days. In the second, the radish seeds germinated in two days and grew for two weeks thanks to the water stored in the soil. 

Today, drylands represent over 40% of the total land mass. Making crops more drought-resistant could boost food production to support the growth of the world’s population, while reducing the consumption of water, which is becoming an increasingly sought-after resource. This solution could also slow down desertification worldwide.

Before the SMAGs can be put on the market, there are still several steps on which the Texan researchers are working: gaining a better understanding of the effect of wind in arid regions, improving the SMAGs’ performance with regard to nutrients, and testing a variety of crops on soils irrigated with these super moisture-absorbent gels. 

SOURCE :

“A new type of soil irrigates itself,” Anthropocene Magazine, November 6, 2020 - www.anthropocenemagazine.org/2020/11/a-new-type-of-soil-irrigates-itself/