Last updated on August 14, 2026 · Originally published February 15, 2023
Soil biology is the one input a grower cultivates rather than simply buys. The research on what it does to cannabinoids and terpenes is finally catching up.
Living soil is a growing medium managed as a biological system rather than an inert substrate. Instead of feeding the plant a measured nutrient solution, the grower feeds a population of bacteria, fungi, protozoa and invertebrates, and that population releases nutrients in forms roots can take up. The soil is the delivery mechanism.
The agronomy is old. Its packaging as “living soil” within modern commercial cannabis is relatively recent, and it has picked up more marketing language than evidence along the way. Here is what is actually established, what is suggested, and what is still just claimed.
What makes a soil “living”?
Soil is not simply a mineral growing medium. It contains weathered rock, organic matter, air, water and living organisms, all interacting as a system. Managing it as a system rather than as a container is the whole idea.
The population densities are the part growers tend to underestimate. Colorado State University Extension notes that a single cup of undisturbed native soil may contain roughly 200 billion bacteria, 20 million protozoa and 100,000 nematodes. Those figures vary enormously between soils, but the organisms are not passengers — they are the mechanism by which organic matter becomes plant nutrition.
Living soil is also, by design, reused. Where a conventional container grow often discards or replaces medium between cycles, a living soil bed is amended and replanted, and a well-managed one can improve rather than degrade over time.
What lives in living soil, and what does it do?
Naming the main organisms makes the soil system less abstract.
Bacteria and fungi do most of the decomposition, breaking organic matter into ionic forms roots can absorb. Mycorrhizal fungi go further, colonising roots and extending their effective reach in exchange for plant sugars.
Rhizobacteria can assist nutrient cycling, make phosphorus more available and influence how plants respond to stress. Some species also fix atmospheric nitrogen, though how much they contribute to cannabis under production conditions is uncertain — cannabis does not form nitrogen-fixing nodules the way legumes do. Plant-growth-promoting rhizobacteria have their own research literature in cannabis.
Biological controls perform some of the work otherwise assigned to pesticides. Bacillus thuringiensis subsp. israelensis (Bti), a bacterium, can target fungus gnat larvae, while beneficial nematodes attack susceptible soil-dwelling pest stages — which is why the good bugs and bad bugs distinction matters more in a living system than a sterile one.
Earthworms fragment coarse organic matter, making it available to microbes, and their castings are themselves a nutrient source.
The practical consequence is that broad-spectrum pesticides and fungicides are not neutral in this system. Inputs that suppress soil organisms suppress the nutrient cycling those organisms perform.
Is “living soil versus salts” a real distinction?
The living-soil-versus-salts framing is partly real and partly a misunderstanding, and it misleads more growers than almost anything else in this subject.
Plants absorb nutrients as ions. Nitrate is nitrate whether it arrived as a dissolved fertiliser salt or as the end product of microbes mineralising compost. Many familiar fertilisers are salts in the chemical sense — monopotassium phosphate, calcium nitrate, potassium nitrate, magnesium sulfate — and the ions they supply are the same ions soil biology produces from organic matter. Roots cannot tell the difference and do not try to.
So the real distinction is not organic inputs versus synthetic fertilisers as competing chemistries. It is about delivery. Salt-based feeding gives precise, immediate control over what the plant receives and when, which is why it dominates indoor and hydroponic production. Living soil gives slower, buffered, biologically mediated release, which is harder to steer and harder to correct quickly, but which maintains a soil system that persists between cycles.
Each has real costs. Soluble fertilisers can accumulate in the medium when inputs exceed plant uptake and leaching, raising electrical conductivity and shifting pH. That is why runoff, root-zone EC and pH are monitored closely in many salt-fed systems, and why the NPK relationship has to be managed actively. Living soil is slower to correct, generally requires more root-zone volume and can be less forgiving in small indoor containers. It is impractical where no soil is used at all.
Does living soil change cannabinoids and terpenes?
Whether living soil changes cannabinoid and terpene content is the question marketing answers confidently and the literature answers cautiously.
The most directly relevant evidence to date is a 2025 study in the Journal of Medicinally Active Plants from Penn State College of Medicine, Penn State’s plant biology programme and Keystone State Testing Laboratory, funded by the USDA’s National Institute of Food and Agriculture. Two hemp cultivars, Tangerine and CBG Stem Cell, were grown identically in two neighbouring fields — one conventionally tilled, one no-till with a long history of cover cropping — and the harvested inflorescence was extracted with supercritical CO₂ and analysed by a state-approved laboratory. The authors describe it as the first published work showing differences in extract composition of outdoor hemp grown in different soil conditions.
Soil testing from the project’s pilot year showed a clear difference between the fields. The cover-cropped field scored far higher on aggregate stability — 35.2 percent against 5.5 — and higher on organic matter, active carbon and soil respiration.
Within this experiment, some of the differences in the extracts were large. THC in Tangerine extracts was six times higher from the tilled field, while CBG in CBG Stem Cell extracts was 3.7 times higher from the cover-cropped field. Those two figures come from different cultivars, and neither pattern held across both.
Three things temper the result, and general coverage has omitted all of them.
The study did not detect a significant difference in total cannabinoid content between the fields. Its clearest findings concerned the distribution among individual cannabinoids rather than the overall amount. Total terpene content was numerically higher under cover crops, around 30 mg/mL against 21.6, but the variance was wide and the difference was not significant.
The direction depends on the cultivar. CBD was about 1.5 times higher in tilled soil for Tangerine, and roughly doubled in cover-cropped soil for CBG Stem Cell. “Living soil raises cannabinoid X” is not what the paper found.
Each regime was represented by a single field, so field and treatment cannot be separated — and the two even differ in soil texture, one a silt loam and the other a clay loam. The authors are candid about a further limitation: as noted above, that soil analysis predates the two seasons the plant data comes from. Their own conclusion is that the findings are best viewed as hypothesis-generating. The study provides credible evidence of an association, not strong causal evidence that tillage or cover cropping produced the differences.
The regulatory implication needs the same care. US hemp compliance is assessed on total THC in plant material on a dry-weight basis, whereas this study measured concentrations in prepared extracts. If the pattern were reproduced in dry-weight flower testing it would matter a great deal, since conditions that push hemp above the THC threshold make a crop non-compliant.
One further result is quietly the most interesting. The two cultivars differed from each other in several individual terpenes when grown in the tilled field, while the study detected no significant differences between them under cover crops. That may suggest cover-cropped conditions narrowed the gap between the cultivars, but non-significance is not proof of uniformity. If replicated, it would be a finding about consistency rather than quality.
An earlier comparison of indoor versus outdoor living-soil cultivation pointed the same direction, with greater terpene quantity and cannabinoid diversity outdoors — but it ran three plants per condition, and light, climate and medium all varied together, so it cannot isolate soil.
The honest summary: genetics set the range, and soil conditions appear to move expression within it. That is a meaningful claim. It is not the claim that living soil produces better cannabis.
How do you build and maintain living soil?
The practices are consistent across extension services, and none of them are exotic.
Start with organic matter. Compost is the primary input, supplying nutrition and supporting the organisms that process it. Worm castings add further organic matter and plant-available nutrients, although their composition varies between products.
Mulch the surface. Organic mulch stabilises moisture, moderates temperature, suppresses weeds, and prevents soil-borne pathogens splashing onto lower leaves during watering.
Disturb it as little as possible. University of Minnesota Extension is direct about the two opposite errors: tilling breaks up fungal networks and soil structure, while walking on beds compacts them and destroys pore space. Fixed walking aisles and hand tools avoid both.
Use cover crops. Rather than leaving soil bare between cycles, cover crops hold it in place and feed it. Different species do different jobs — hairy vetch fixes nitrogen, cereal rye contributes carbon and organic matter. Clover and buckwheat are also common choices in cannabis beds.
Rotate where the production system allows. Outdoors, growing the same crop in the same soil indefinitely can deplete particular nutrients and allow specialist pathogens to build. Rotation interrupts both. In permanent indoor beds, careful testing, sanitation and pathogen monitoring have to perform some of the same work.
For the mechanics of amendment ratios and bed construction, our guide to soil building techniques goes further, and the beneficial microbes piece covers inoculation in more depth.
How do you know whether living soil is working?
Whether a living soil is actually functioning gets treated as a matter of faith more often than it should be, which is odd, because it is measurable.
Standard soil tests give pH and nutrient concentrations, and both should be tracked rather than assumed — living soil drifts as it matures. Organic matter percentage is a slower-moving indicator of whether the system is accumulating or depleting.
Biological activity itself can be measured. Soil respiration — the carbon dioxide released as organisms metabolise — is an indicator of current biological activity. It is not a census of organisms, and it changes with temperature, moisture and recent additions of organic matter, but tracked consistently it can reveal whether activity is rising or falling.
For a magazine whose subject is analytical testing, the point is worth stating plainly: the same discipline growers apply to potency and terpene panels applies here. Soil claims are testable, and a grower who tests knows something a grower who believes does not.
What living soil does not do
Several claims about living soil travel further than the evidence supports, and they are worth separating from the ones that hold.
It does not eliminate inputs. It changes them from bottled nutrients to compost, amendments, mulch and cover crop seed, which is a different cost structure rather than an absent one.
It does not by itself confer organic certification. Federally compliant hemp can be USDA-certified organic, but only through the normal certification process. Marijuana cannot receive USDA organic certification under current federal law, although some states operate comparable programmes. “Living soil” is a description of practice, not a certification.
It does not guarantee higher yields. Performance depends on soil volume, nutrient availability, irrigation, genetics and management, and living soil can be considerably slower to correct when something goes wrong.
And it does not reliably produce more terpenes. That may turn out to be true — the 2025 field data is genuinely encouraging — but it is not established, and the most directly relevant living-soil comparisons discussed here still confound soil with other variables.
What living soil unquestionably does is create a biologically mediated nutrient-cycling system that can remain productive across repeated cycles and reduce dependence on soluble fertilisers. It has now also been associated with meaningful differences in cannabinoid and terpene composition, although the causal evidence remains preliminary. For a plant sold largely on its chemical profile, that is reason enough to take the soil seriously.
For how those compounds are measured once the plant is harvested, start with our guide to cannabis terpenes.
References
- Colorado State University Extension. The Living Soil, GardenNotes #212. Read the guide
- University of Minnesota Extension. Promote Healthy Soil in Your Garden. Read the guide
- Chacon FT, Raup-Konsavage SA, Greenland K, et al. Impact of Soil Quality on Cannabinoid and Terpenoid Content of Cannabis sativa L. Journal of Medicinally Active Plants. 2025;14(2-3):19-30. Read the full text
- Sustainable Agriculture Research and Education. Building Soils for Better Crops, 4th edition. Read the book
Originally published February 15, 2023. Updated August 14, 2026: merged with two earlier articles on living soil cultivation and living soil versus salts, removed a citation that did not support its claim, and added the 2025 field research on soil quality and cannabinoid content.
Reviewed by Nani Frenkel, chief editor.
