A new, biodegradable hydrogel that could help farmers better use water during the growing season, is being developed by Washington State University researchers. 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. 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. It is designed so the gel can swell to soak up water and gradually shrink to release it. It will repeat the soak-and-shrink process. Most of the available commercial hydrogels are petroleum based, causing concern about contamination, but not this hydrogel. These pellets will mix into the soil. 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.The hydrogel will not keep the water forever but will gradually release it to be sucked up by roots. Farmers will still need to water the crops, but will not 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.

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.