New, biodegradable hydrogel could help farmers store water for crops

Kristi Pihl, Tri-City HeraldJuly 13, 2014 

WSU Hydrogel research

A super-absorbent hydrogel, developed by a research team led by Jinwen Zhang, an associate professor of Washington State UniversityÕs School of Mechanical and Materials Engineering, is being tested in California fields this summer to see how well it helps farmers conserve water.

COURTESY WSU

A new, biodegradable hydrogel being developed by Washington State University researchers could help farmers better use water during the growing season.

When placed near the roots of crops, the hydrogel will absorb up to 250 times its own weight in water and then will slowly release the water, allowing thirsty roots to drink what otherwise would have been lost in the soil.

The super-absorbent hydrogel, developed by a team led by Jinwen Zhang, an associate professor of WSU's School of Mechanical and Materials Engineering, is being tested in California fields this summer. Zhang also has applied for a patent.

Mid-Columbia farmers have embraced water conservation, for stewardship and to cut down on expenses, including the electricity used to pump water.

Drought concerns are common because the Mid-Columbia and Yakima Valley depend on melting snowpack to fill area rivers during the summer.

Most of the available commercial hydrogels are petroleum based, causing concern about contamination, said Zhang, who specializes in biobased polymer material. He said he is always looking for ways to create biobased options that can replace petroleum-based polymer materials. A polymer is a big molecule made up of little molecules strung together in a row.

Zhang, who has been working on the hydrogel for about two years, said he hopes the hydrogel, which is similar to what is used in absorbent diapers, will allow farmers to use less water while still seeing good plant health.

The hydrogel is solid like a pellet until it comes into contact with water, when it then becomes a clear gel, Zhang said. It's designed so the gel can swell to soak up water and gradually shrink to release it.

It will repeat the soak-and-shrink process. The pellets will be mixed into the soil.

The hydrogel won't keep the water forever but will gradually release it to be sucked up by roots, he said. Farmers will still need to water, but won't have to use as much to get the same results.

The hydrogel will lose its ability to hold water after a certain amount of time, Zhang said. But because it is biodegradable, it can remain in the soil without causing harm, and actually becomes a source of nitrogen as the soy protein breaks down.

Farmers may need to increase the amount they water over the course of the growing season, said Travis Woodland, Voiland College of Engineering and Architecture, business development director.

Woodland compares the hydrogel to a water battery. It provides a battery pack of water for plants to draw from after the rest of the water has slipped away. It could help farmers even when there isn't a drought.

Researchers are testing the durability of the hydrogel in California fields in partnership with mOasis Inc. Zhang said they are looking for more companies to help field test the hydrogel.

Researchers may tweak the hydrogel after they receive the results from the initial field tests at the end of the summer.

Woodland said it will be fairly easy to start producing enough of the hydrogel for it to be commercially available.

The manufacturing process is fairly simple since Zhang said they wanted to produce a product that would be economical for farmers. But how soon it is available really depends on the results of the field trials and farmer demand.

The United Soybean Board, a U.S. Department of Agriculture-affiliated program, supported the research. The U.S. produces about half of the world's supply of soybeans.

-- Kristi Pihl: 509-582-1512; kpihl@tricityherald.com

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