(Todd Epp, Northern Plains News)– South Dakota hemp farmers may soon have a new tool for ensuring their crops stay within legal THC limits: soil management practices that can dramatically alter cannabinoid levels in their plants. A federally funded study published in the Journal of Medicinally Act ive Plants found that the type of soil hemp grows in significantly impacts THC, CBD and other cannabinoid concentrations — sometimes by factors of three to six times, according to the peer-reviewed research. The findings could prove critical for South Dakota’s developing hemp industry, where exceeding the 0.3 percent THC threshold means crops must be destroyed.​ The U.S. Department of Agriculture’s National Institute of Food and Agriculture, Penn State College of Medicine, and Pennsylvania medical cannabis business PA Options for Wellness funded the research comparing hemp grown in conventionally tilled fields versus cover crop fields, according to the study.​ Conventional Tillage Spikes THC Production The study’s most striking finding: Hemp grown in conventionally tilled soil produced THC levels up to six times higher than plants grown using cover crop methods, according to the research. This discovery could help South Dakota farmers choose cultivation practices that keep their crops below federal THC limits while still producing desired CBD levels.​ “Poor soil quality appears to result in higher levels of THC production, whereas higher soil quality may result in higher levels of the precursor cannabinoid, CBG,” researchers wrote in the journal paper.​ The study examined two hemp cultivars — Tangerine and CBD Stem Cell — grown in neighboring Pennsylvania fields using different soil management approaches, according to the research. Cover crop fields used no-till methods that enhance soil biology, while conventional fields employed traditional tillage.​ Results varied by cultivar, the study found. The Tangerine variety grown in conventional soil produced CBD levels about 1.5 times higher than cover crop soil, according to the research. But the CBD Stem Cell cultivar showed the opposite pattern, with CBD levels doubling in cover crop fields, researchers reported.​ Cannabigerol, or CBG, reached levels 3.7 times higher in plants grown with cover crops, according to the study. The precursor cannabinoid has gained attention for potential therapeutic applications.​ First-of-Its-Kind Research “This is the first study to show differences in extract composition of outdoor cultivated hemp grown in different soil conditions,” the researchers wrote in the paper.​ The findings suggest farmers could fine-tune cannabinoid profiles through soil management rather than relying solely on genetics, according to the study. This could prove especially valuable for South Dakota producers navigating the state’s hemp regulations while trying to maximize crop value.​ Earlier this year, an industrial farmer told Marijuana Moment that expanding South Dakota’s hemp supply chain would bring more small-scale processing and manufacturing into the state while pulling heat-trapping carbon dioxide from the atmosphere.​ Implications for South Dakota Agriculture The study examined what researchers call the “tilth aspect” of soil health — comparing conventional tilled fields to no-till cover crop fields, according to the paper. Both approaches are common in South Dakota agriculture.​ “The outcome of this study provides outdoor growers with information on the effects soil health can have on cannabinoid and terpene content in hemp,” researchers wrote.​ The authors cautioned that more research is needed to understand enzyme levels responsible for converting CBG into CBD, THC and other cannabinoids, according to the study. That knowledge could explain why CBG accumulates in plants grown in cover crop fields, researchers said.​ “A comparison of hemp extracts of two different cultivars grown in both cover crop soil and conventional field soil revealed significant differences in specific cannabinoid and terpene concentration,” researchers wrote in the paper.​ For South Dakota’s agricultural community, the research offers a potential roadmap for developing a sustainable hemp industry built on existing soil management expertise.​ ...read more read less