After the Volts: Is Weed Electrocution Safe for the Soil?

We know getting zapped with high voltages of electricity can be a deadly affair for weeds, which has made weed electrocution a promising area of study and experimentation for researchers and farmers alike. 

But what do those waves of electrical power do to the innocent bystanders of the crop fields – the earthworms, microbes and tiny insects that call the soil under our feet home? 

Well, not too much, according to preliminary results from an assortment of research trials on weed electrocution happening across the United States. 

Aleah Butler-Jones (right) helps with testing of the Zasso electric weeder at Cornell University. (Photo credit: Lynn Sosnoskie, Cornell)

For example, a University of Missouri research team led by Dr. Kevin Bradley has found no difference in the health or survival of red wriggler earthworms dug up from electrocuted and non-electrocuted plots where they used The Weed Zapper in 2022. Nor did they find any differences in the fate of the many beneficial bacteria or fungi that make up the soil microbial communities in the plots. 

Likewise, preliminary results from a multi-state evaluation of the Zasso electric weeder aren’t showing any ill effects on soil-dwelling arthropods, such as springtails (Collembola) or mites, nor the respiration rates of the microbial community, says Dr. Lynn Sosnoskie, a weed scientist working in specialty crops at Cornell University. 

Preliminary research results from the University of Missouri, as displayed at the North Central Weed Science Society’s 2023 meeting, show no significant effects on soil communities and health from weed electrocution. (Poster credit: University of Missouri Weed Science)

Both groups of researchers are also interested in how weed electrocution might affect less friendly soil-dwelling species. The Mizzou study examined the fate of soybean cyst nematodes on soybean roots, while Sosnoskie’s trials examined the weed seeds buried in the soil, waiting their turn to emerge. 

So far, however, just like their more beneficial brethren, neither the nematode pests nor the weed seedbank have shown any ill effects from weed electrocution happening above them. 

This lack of impact on the creatures of the soil is good news for growers who are increasingly turning to alternative weed control measures, Sosnoskie says. That includes row crop growers facing rising herbicide-resistance concerns and regulatory scrutiny. But the most pressing demand for non-chemical weed control has arisen among specialty crop growers, especially those who grow perennial crops such as orchards or vineyards, Sosnoskie says.

“These are very unique agricultural systems – once they are in place, they are established, and you can’t use tillage or other mechanical disturbances as easily,” she points out. Moreover, between residue limits, market restrictions, and consumer preferences, herbicide options tend to be limited. And hand-weeding, while effective, is time-consuming, expensive and reliant on labor that is increasingly in short supply. 

“So [novel] alternate strategies are of great interest to this community,” Sosnoskie says. That’s why she teamed up with researchers at Oregon State University and the University of California-Davis for a three-year study on the effect of weed electrocution in perennial crops. You can see videos and photos of their research so far here

Sosnoskie also studies the effect of other electric weeding implements, specifically The Weed Zapper, on specialty and row crop farms in her region. She has found that growers are concerned with more than just efficacy and cost. 

“There are a lot of growers who are interested in what weed electrocution could mean for soil health and sustainability,” Sosnoskie says. “They have questions about what it costs to get and run and service these units, yes, but the bigger costs to the environment are also a question.” 

See more on the University of Missouri’s weed electrocution research in row crops here, and Cornell University’s research in this area here. See more on Sosnoskie’s research at Cornell here and Bradley’s here

 For more information on weed electrocution from GROW, see the News Page

Article by Emily Unglesbee, GROW; header photo from Cornell University; feature photo from USDA, CC0 Commons license.