UTSA researchers create synthetic roots that stabilize soil, prevent erosion

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(July 30, 2012) -- After three years of research, scholars at The University of Texas at San Antonio have created a process for injecting plants with polymers to develop a synthetic root system that stabilizes soil.

Once optimized, the composite material can be applied to structures and roadways, where soil stability is critical, and to dams, levees, embankments, landfills and other soil structures that are prone to landslides and erosion.

"The roots of plants and trees help keep soil in place," said Drew Johnson, associate professor in the UTSA Department of Civil and Environmental Engineering. "However, plants are prone to diseases, drought, ageing and animal grazing, and when the plants die, their root systems weaken. This leaves the soil less stable and prone erosion or shifting. We thought that if we could fill the roots with a plastic that has a low biodegradability factor, we would get the benefits of the root system even after the plant dies."

Funded by a $354,000 grant from the National Science Foundation, Johnson, with help from Mark Appleford, UTSA assistant professor of biomedical engineering; Valerie Sponsel, UTSA professor of biology; and UTSA graduate student Karl Eisenacher, developed the composite material and tested it on the roots of Artemisia annual (Sweet Annie), a hardy plant that grows rapidly and has a dense root structure. The plant also has a single stem, making it ideal for polymer injections.

A series of tests comparing natural Sweet Annie roots to the same roots injected with the polymer suggest that the infusion of the polymer increased the root strength.

When the NSF reviewed the team's 2009 proposal, one reviewer noted, "This research is a beginning, in its infancy, high-risk, highly innovative, but with tremendous future potential."

The scholars now are seeking to optimize the process so the polymer permeates the outer parts of a root system, once it is injected.

>> Their article, "Strength Enhancement of Plant Roots through Polymer Infusions," was published recently in the Journal of Composite Materials.