Engineers Are Developing Self-Watering Soil for Drought Farming

Over the past 100 years, droughts have become both more severe and more frequent.

Drought conditions are, obviously, of immense importance to agriculture. There have been a number of developments to try to coexist with droughts—more drought-tolerant plant breeds, for example. But have you considered Super Moisture Absorbent Gels?

Researchers at the University of Texas at Austin have just published a scientific article about a new irrigation system using hydrogels. Hydrogels are polymers that attract and hold water; you can think of them as super-sponges, or those Orbeez balls that swell up with water. But hydrogels can also be manipulated in many different ways, including where they absorb water from and, perhaps most importantly, when they release their stored water.

The Texas researchers have been working with this particular sort of hydrogel for awhile; they first published work on agriculture-focused hydrogels back in January of 2019. But the new research shows a full system of irrigation using these hydrogels. 

Here are the basics: These hydrogels, when left outside, will absorb ambient humidity from the cooler nighttime air—in other words, they’ll suck up moisture and swell. But these hydrogels are engineered to release their stored water when they reach certain temperatures. That means that they’ll essentially snag water from the air at night, and then when it heats up in the daytime, they’ll release that water. 

The team experimented by growing radishes in its own hydrogel soil, along with a control group of radishes in dry, sandy soil. Both radish groups were watered initially, to get them set, and the control group was actually given some more water over the first few days. But after two weeks, the radishes in the hydrogel were just fine, and the hydrogel soil retained 40 percent of its water after four weeks. The control radishes, on the other hand, perished within two days of watering stopping, and that sandy soil had only 20 percent of its water after four weeks—not enough for the radishes to survive.

Though this team has been working on these hydrogels for a while, it’s still early days for the technology. Cost will be a major factor, as will various specifics around outdoor temperatures, types of plants to be grown, humidity levels, and types of soil. But hydrogels are proving to be an interesting possibility for coping with drought conditions; a study from late last year looked at using hydrogels to deliver precise doses of water and nutrients to potatoes, and found it highly effective. Hydrogels: a technology to keep an eye on!