MITCHELL, SD (Mitchell Now) — South Dakota hemp farmers may soon have a new way to reduce the risk of crops exceeding legal THC limits, thanks to new research showing soil management practices can dramatically affect cannabinoid levels in hemp plants.
A federally funded study published in the Journal of Medicinally Active Plants found that the type of soil hemp is grown in can significantly alter THC, CBD, and other cannabinoid concentrations — in some cases by three to six times. The findings are especially relevant in South Dakota, where hemp crops testing above 0.3 percent THC must be destroyed.
The research was funded by the U.S. Department of Agriculture National Institute of Food and Agriculture, Penn State College of Medicine, and Pennsylvania-based medical cannabis company PA Options for Wellness.
Researchers compared hemp grown in conventionally tilled fields to hemp grown using no-till cover crop methods. Hemp grown in conventional soil produced THC levels up to six times higher than plants grown in cover crop fields, according to the study.
“Poor soil quality appears to result in higher levels of THC production,” researchers wrote, while healthier soils were linked to higher levels of cannabigerol, or CBG, a precursor cannabinoid drawing increased interest for potential therapeutic uses.
The study examined two hemp cultivars and found results varied by plant variety, suggesting farmers may be able to fine-tune cannabinoid profiles through soil practices rather than genetics alone.
Researchers noted the findings could help outdoor hemp growers manage risk and maximize crop value using soil techniques already common in South Dakota agriculture. They cautioned that additional research is needed to better understand the biological processes driving the differences.
For South Dakota producers, the study offers a potential path toward a more sustainable and compliant hemp industry rooted in soil health management.