What comes naturally
Removing weeds through restoration, not poison
When Katie Dean and Neil Bertrando first laid eyes on the acres of land they were tasked to restore, it was overrun with invasive tall whitetop; the soil was hard, salty and full of boron and mercury; and few native plant species were in sight. The property—along Steamboat Creek and the Truckee River at University of Nevada, Reno’s Main Station farm—was severely disturbed by a history of flooding, grazing and intensive use for the past century. Parts of it were once even used to store sewage sludge.
To deal with the weed-infested land, they could have taken the conventional route: Take backpack sprayers of herbicide and spray twice a year for up to six years. Their employer, local nonprofit Great Basin Institute, is well-versed in that method, as that’s typically how its crews of Nevada Conservation Corps members control invasive weeds on public lands across the state. But this time, GBI got a $575,000 grant to try something new and rather holistic—get rid of weeds by adding good things to the land, rather than toxins.
“The weed problem here was so intense, doing herbicide treatment on over a hundred acres of land with a monoculture of tall whitetop didn’t seem realistic,” Dean told a couple dozen members of local conservation agencies on a recent morning at the site. Instead, they decided to approach it like a soil restoration project. Dean and Bertrando asked themselves why tall whitetop liked the site so much. The soil was anaerobic, compacted and bacterially-dominated—conditions in which tall whitetop thrives. Native species favor aerobic, decompacted and fungally-dominated soil, Dean explained. So this past spring, GBI began creating those conditions in the soil.
Using a Yeoman’s plow, which decompacts the earth without disturbing the top soil, they aerated the soil. Then, using their own compost blend, they use a BioBrewer, a piece of equipment that “brews” compost tea or extract, which can then be sprayed over the land to inoculate and get beneficial fungi into the soil. Then they reseed with a variety of native species.
When asked about the threat of flood or of more weed seeds traveling down the nearby waterways to the site, Bertrando said, “I’m not worried about the seeds coming because the [weed] seeds are already here.” The idea is to create a resilient ecosystem and healthy soils, where tall whitetop and other invasives won’t be able to compete with native species, thus making future weed abatement projects unnecessary. Dean and Bertrando say they’re already seeing results, especially in areas adjacent to intact ecosystems.
Though novel for Nevada, similar methods are widely used in California, where many of the chemicals Nevadans freely use on federal and state lands are banned. “California saw a huge class-action lawsuit looming and pulled herbicides off the commons,” said Dean, though a hard-to-get permit can be used on federal lands there. To spray herbicides and pesticides in Nevada, you need a certified applicator’s license, which is relatively easy to obtain by taking a brief class and scoring 60 percent on an exam.
GBI is making the plow and BioBrewer available to others on a public-works basis. They will also make the extensive data they’re collecting from the site available to the public so that more weed abatement projects may be done without using herbicides.
The project is slated to be underway until December 2011, though it may be extended to 2013.