Holy Cacti! Is the Prickly Pear the Antidote to Toxic Soil?

Farmers in California are waging war on selenium in their fields with the help of a spiny savior.

prickly pear cacti
Prickly pear cacti are super plants when it comes to cleaning up after irrigation damage. (brewbooks/Creative Commons)
Megan is a sucker for sustainable agriculture and a good farmers market, she likes writing about food almost as much as eating it.

A billon-dollar farm belt almost half the size of Yosemite National Park and home to 250 different crops is nothing to sneeze at. That's why farmers in the western side of California's San Joaquin Valley are considering an unusual weapon to salvage contaminated soil in the area: cacti.

Prickly pear cacti, resilient little brutes who can withstand super salty soils and dry climates, are being planted in the Valley to reduce the high levels of selenium that have flooded the area after years of artificial irrigation. Selenium, a chemical that is good for humans in small doses and toxic in large doses, has saturated the soil, bringing it to unhealthy levels.

The Fresno Bee reports that selenium in irrigation drainage "widely killed and maimed wildlife during the 1980s at Kesterson Reservoir on the Valley's west side." Reporter Mark Grossi says that farmers have "been scrambling for a cleanup ever since."

The cacti prove promising. As they grow, they suck up the region's salinous water with no problem and clean up chemical contamination to boot. Plus, the spiny guys are slow in their sucking, drawing in water at a pace that keeps them from absorbing levels that would be toxic to animals and birds who bite them. As an added bonus, selenium saturated cacti could also be sold abroad to Europe, Australia, India, and China, where diets are sometimes deficient in selenium.

Is there anything the resilient wonder plant can't do?

With regard to selenium, no. But Gary Bañuelos, a federal plant and soil scientist at the Agriculture Research Service in Parlier, says that this is not an overnight fix. He speculates it will take a number of years to make real difference. 

The cacti also don't solve an additional problem of irrigation, which is an excess supply of salt. Layers of clay beneath the west-side Valley's surface prevent irrigation water from permeating the ground, keeping the salty water trapped on the surface where it accumulates on crop roots. 

Still, farmer John Diener, who's been experimenting with irrigation solutions since the mid-90s, says the cacti solution is worth the effort. 

"Some people would rather retire this land rather than working on the problem," Diener told the Fresno Bee. "I think that's ignoring the reality of the world's need for crops we grow."

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