Hemp oil leftover waste repels and stresses earthworms in soil tests
Bjedov D, Gašparić M, Tišma M, Velki M
Soil Health
If you compost or amend garden beds with hemp byproducts touted as 'natural' soil boosters, this research shows earthworms actively flee that material and show signs of nervous-system and detox stress within just two days.
When hemp seeds are pressed for oil, the leftover pulp (called pomace) is sometimes suggested as a cheap soil additive or compost ingredient. Scientists mixed this pomace, both plain and fermented with a fungus, into soil and watched how earthworms reacted. The worms avoided the hemp-treated soil almost entirely and showed chemical signs of nerve stress and liver-like detox strain, proving this 'waste product' isn't the harmless filler it's often assumed to be.
Key Findings
Earthworms exposed for 48 hours showed strong, consistent avoidance behavior toward soil amended with both non-fermented and fermented (3-day and 10-day) hemp pomace.
Non-fermented hemp pomace caused the strongest disruption to acetylcholinesterase (nerve function) and detoxification enzymes (carboxylesterase, glutathione S-transferase, multixenobiotic resistance).
Oxidative stress markers (catalase, glutathione, reactive oxygen species) showed no consistent pattern, meaning behavior and enzyme biomarkers were more sensitive indicators of harm than oxidative stress tests.
chevron_right Technical Summary
Earthworms strongly avoid soil mixed with hemp seed oil processing waste, whether raw or fermented, and the waste disrupts their nervous system and detox enzymes. This suggests hemp pomace, often proposed as a soil amendment, could harm soil life rather than help it.
Abstract Preview
Original paper
Responses of the earthworm Eisenia andrei to non-fermented and fermented hemp pomace: Altered neurotoxic and detoxification mechanisms with strong behavioural avoidance.
Residues from industrial hemp seed oil production are increasingly explored for agricultural and biorefinery applications, yet their ecological compatibility with soil organisms remains poorly unde...
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Hemp, or industrial hemp, is a plant in the botanical class of Cannabis sativa cultivars grown specifically for industrial and consumable use. It can be used to make a wide range of products. Along with bamboo, hemp is among the fastest growing plants on Earth. It was also one of the first plants...