By Gwen Roland
University of Georgia

For much of two centuries, farmers grew velvet beans to control
weeds and build up organic matter in the soil in their fields.
Now, University of Georgia scientists are taking a second look at
this old favorite.

“When my grandfather was diagnosed with Parkinson’s disease, I
told him I was researching the plant from which a drug to treat
it is made,” said Nicole Martini, a UGA horticulture graduate
student.

“A few months later,” she said, “he showed me his medicine bottle
and said, ‘Look, here’s your plant.”

Velvet beans’ pharmaceutical use is fairly new in the United
States. But people elsewhere have used it to treat ailments from
depression to snakebite.

L-dopa

The medicinal properties come from a high concentration of
L-dopa, a precursor of dopamine. This may be why most insects
avoid it. Doctors use L-dopa to treat Parkinson’s disease.

Velvet beans were a favorite cover crop in the South for more
than 150 years. “Weeds don’t like velvet beans,” Martini said.
“And they contribute tons of biomass per acre.”

It provided forage for livestock. It controlled weeds. It added
nitrogen and biomass to the soil. But it disappeared from the
rural landscape in the mid-1950s, though, when better roads and
low-cost farm chemicals enabled farmers to plant the same crops
year after year.

With growing concern over chemical inputs, researchers are
looking anew at velvet beans. Martini’s experiments in Georgia
focus on biomass and weed control. She uses the Georgia Bush
variety bred by UGA researcher Sharad Phatak.

Many benefits

At the UGA campus in Tifton, Ga., she and other scientists study
velvet beans’ benefits. “Just 120 days after planting, velvet
beans produced 65.6 tons of fresh biomass per hectare, about 50
percent more biomass than Sunn Hemp,” she said.

This supported the theory that velvet beans can improve the
organic matter content and fertility of soils in Georgia, she
said.

“We also found that a solution prepared using velvet bean residue
in water reduced growth of crab grass, sicklepod and pigweed,”
she said. “It didn’t eliminate them, but it did reduce them.”

From the data, she concludes that through a combination of the
added biomass, the quick growth that shades out weeds and the
allelopathic effect, a farmer would see fewer weeds if he used
velvet beans as a summer cover crop before planting fall
vegetables.

Adding those traits to the potential now to sell beans to drug
companies could mean a major comeback for velvet beans.

“Farmers are more inclined to use cover crops if some part of
that crop also has economic value,” Martini said.

The velvet bean study was funded by a grant from the Southern
Region Sustainable Agriculture Research and Education Program.

(Gwen Roland is a news editor with the University of Georgia
College of Agricultural and Environmental Sciences.)