Hemp grown in copper-contaminated soil renders usable stalks, boosts CBD production

Hemp is good for cleaning up soil contaminated with copper – and copper can be good for hemp, according to Greek researchers who have looked at the plant as an option for phytoremediation.

Scientists from the departments of agriculture at the University of Thessaly and Aristotle University not only found that hemp effectively absorbs copper from heavily contaminated soils, but that the process boosts CBD levels in the hemp plant’s flowers.

“Hemp was revealed to be a tolerant plant, growing successfully in soils with varied particle size distributions supplemented with two levels of Cu (copper) concentrations,” the researchers reported in a recent study. “Cu proved to have a favorable effect on the plants at both contamination levels, as evidenced by the plants’ growth characteristics, above-ground weight, height, and photosynthetic capability.”

The study was published in Waste and Biomass Valorization, a scientific journal of Berlin-based Springer Nature.

More copper, more CBD

The production of CBD appears to increase as the concentration of metals in cannabis-growing soil increases, according to the research. “Therefore, hemp cultivation is promising for Mediterranean soils, as it produces high amounts of CBD in response to metal pollution stress and remediates polluted soils,” the authors observe.

“Enhanced CBD production in response to increasing soil copper levels is a particularly interesting outcome,” the paper observes. “Future studies could explore the hypothesis that CBD production may represent a genetic response to stress induced by its cultivation in toxic environments.”

Gathers in roots

The study found that copper accumulates primarily in plant roots and moderately in the lower part of stem shoots, generating metal-free stalks appropriate for industrial use, and making hemp “an ideal candidate for phytoremediation” because it provides “enormous” biomass over a short life cycle.

Italian researchers who studied hemp for soil cleanup reported in 2021 that even plant stems that show the presence of heavy metals can safely be used in such end products as hempcrete and pressed energy pellets, from which metals can be extracted for re-use from leftover ashes.