Undergraduate earns national notice for her water scarcity solution

Fourth-year environmental studies major Visala Tallavarjula made it to the final round of the 2022 Collegiate Inventors Competition with her innovative irrigation technique, Sequestron. She was one of only five undergraduate finalists in the contest run by the National Inventors Hall of Fame.

Sequestron promises to increase food production while reducing water use — all with readily available materials.

“You can do this in your own garden,” says Tallavarjula, who previously won grants from the Strauss Scholarship Foundation and UC Berkeley’s Big Ideas Competition to pilot Sequestron in Arizona and India.

Born and raised in Santa Clara, she was first inspired to invent Sequestron on a drive through California’s Central Valley, passing by field after field irrigated by sprinklers. “You could literally see the water evaporating off the fields because it was hot,” she recalls.

Her solution? Using a topsoil layer to suppress evaporation by way of an infiltration insert, keeping water in the root zone and preventing it from reaching groundwater reserves by spreading a layer of soil and charcoal below the roots.

Tests suggest the system increases crop yield while cutting water use in half. The perlite-amended top layer alone reduces water use by 30%. Sequestron even enables farmers to grow crops in sand.

“This could actually arrest desertification,” says Tallavarjula.

Visala Tallavarjula / Photo by Trieu Nguyen

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