How to make JADAM Microbial Solution at home

The microbes you want in your beds already live a few hundred metres away.

JADAM Microbial Solution (JMS) is a homemade microbial inoculant, made by fermenting forest leaf mould with a boiled potato in salted water. You will also see it written as JADAM microbe solution or microorganism solution; they are the same ferment. The leaf mould carries indigenous microorganisms. The potato feeds them. After one to three days at room temperature you have a working solution to drench across your soil, or dilute and apply as a foliar spray.

The method comes from Cho Youngsang, the Korean farmer and chemist who founded JADAM in 1991. JADAM is short for jayonul damun saramdul, meaning “people who resemble nature”. The system is built around inputs anyone can make at home with a bucket, a forest walk, and a few quid’s worth of ingredients.

What follows is the recipe I use, based on Cho’s original, with three optional additions that suit a Dr Forest soil-feeding programme.

In short

What it is. A 1–3 day anaerobic ferment of forest leaf mould, water, salt and potato. Costs pennies a litre and finishes in a bucket.

What it does. Multiplies indigenous soil microbes and lets you drench them across your beds. Best applied just before transplanting and through the fast-growth phase.

What JMS does in soil

A handful of forest leaf mould holds tens of billions of microorganisms: thousands of bacterial and fungal species, plus protozoa, nematodes, archaea and viruses. The reason most vegetable beds underperform is rarely a lack of fertility. It is a lack of biology.

JMS transfers some of that forest biology to your beds, and multiplies it on the way.

1. Forest floor as inoculum. Leaf mould is the dark crumbly layer below the recently fallen leaves, often resembling worm castings. A small handful is your seed culture.
2. Salt as a selector. A 0.1% salt solution is too weak to kill anything outright. It sets up a mild stress that favours halotolerant strains and dampens runaway pathogens.
3. Potato starch as food. Boiled potato pureed into the water provides simple carbohydrates microbes metabolise quickly. The population doubles every few hours.
4. Anaerobic fermentation. With limited oxygen the surviving microbes are the ones that thrive in heavy, compacted soils. The bubbles you see on the surface are CO₂ from active fermentation.

When the bubbles coalesce into a “raft” or circular foam disc across the surface, the population is at peak. Apply within 24 to 48 hours. Once the raft starts to break, the microbes are dying off.

The recipe

Cho’s original uses four ingredients: water, leaf mould, salt and a potato. The version below adds three optional boosters that round out the trace mineral and fungal sides of the brew. Quantities are scaled to a 4-litre batch, which is enough for one bed of around 5 m² when diluted.

Ingredient	Per 4L	What it does
Filtered or rainwater	4L	Carrier. Tap water needs 24 hours to off-gas chlorine, which kills microbes.
Boiled potato, blended to a puree	25g	Starch food source for the microbial bloom.
Sea salt	4g	Selection pressure (0.1% solution).
Leaf mould	4–8g	The microbial inoculum, taken from below the leaf litter under a mature tree.
Volcanic rock dust (optional)	40g	Trace minerals microbes need to function: silicon, calcium, iron, manganese.
Humic acid (optional)	1.6g	Long-chain carbon substrate that feeds microbes after the potato is gone.
Mycorrhizal inoculant (optional)	1.6g	Adds fungal diversity to a brew that would otherwise lean bacterial.
Fresh plant trimmings (optional)	A handful	Cuttings from the plant you’ll feed. The microbes adapt to the host.

On sourcing leaf mould: take it from below a well-established tree in healthy woodland or an old hedgerow. Avoid playing fields, roadsides, recently sprayed land, or anywhere you wouldn’t pick blackberries.

Method, step by step

1. Fill a 5L bucket with 4L of water. Use rainwater, or tap water that has been left out for 24 hours.
2. Stir in the salt and rock dust. The water will go slightly cloudy.
3. Add the potato puree. Mash thoroughly. More surface area means faster microbial colonisation.
4. Stir in humic acid and mycorrhizal inoculant if using. They are powders and disperse easily.
5. Knead in the leaf mould and any plant trimmings. Some growers tie these in a mesh bag suspended in the water; others stir them in. Either approach works.
6. Cover loosely. A breathable lid or a tea towel is fine. You want gas to escape and limited fresh oxygen to enter.
7. Hold at 18 to 22°C. A garage in summer, a shed with a heat mat in winter, near a south-facing window in spring. Below 18°C the ferment stalls. Above 25°C you risk killing strains.
8. Watch for the raft. Day one shows scattered small bubbles. By day two or three those bubbles coalesce into a continuous foam disc. That is the signal.
9. Use within 24 to 48 hours of the raft forming. Once the raft starts breaking up, the microbes are dying back. JMS has no shelf life worth speaking of.

You’re not buying microbes. You’re growing the ones already in your soil.

How to apply it

Root drench: 1:10. 1L JMS in 10L of water, applied at 5–10L per m². Bare soil with no plants in yet can take it at full strength.

Foliar spray: 1:20. 1L JMS in 20L of water with a wetting agent. Spray to runoff in early evening when stomata are open and UV is low.

Pre-planting: three drenches over the two weeks before transplanting. The bed arrives at planting day biologically primed.

Maintenance: monthly through the season. Step up to weekly in the two weeks before flowering or fruit set.

Cho’s published claims for consistent JMS application include reduced soil salinity, faster root settlement after transplanting, and suppression of some nematodes and wilting pathogens. The root settlement effect is well documented in JADAM’s own field trials and is consistent with what is known about microbial priming. The salinity and nematode claims have less independent peer-reviewed evidence behind them, though the underlying principle (a thriving microbiome out-competes opportunistic pathogens) is well established in soil ecology.

Where JMS fits in a feeding programme

JMS is a microbial input. It is not a fertiliser. The nutrient load from a 1:10 drench is negligible. Its job is to keep the soil ecosystem populated, alongside whatever mineral and organic feeding programme you already run. If you have used a bought microbial inoculant like EM-1 or a bokashi bran, JMS is the make-your-own version of the same idea, at a fraction of the cost.

	JMS	EM-1	Bokashi Bran	Compost tea
Microbial type	Anaerobic ferment	Aerobic + facultative	Solid fermented bran	Aerobic brew
Microbial source	Local leaf mould	Cultured EM blend	Cultured EM on bran	Mature compost
Cost	Pennies per litre	~£1 per litre	~£15 per kg	Free if you have compost
Shelf life	24–48 hours	12 months	12 months	A few hours
Effort	Medium	None	None	High

If you want a microbial input with a long shelf life and no brewing window, Dr Higa’s Organic EM-1 and Bokashi Bran cover similar ground. Both use Professor Teruo Higa’s Effective Microorganism culture, developed in Okinawa in the 1980s, which contains many of the same functional groups as JMS in a controlled, reproducible blend.

JMS suits gardeners who already work closely with their local soil and want to amplify what is there, rather than introduce a cultured population from elsewhere.

For brewers, JMS pairs well with three Dr Forest products:

• Mycorrhizal inoculant at transplanting. JMS sets up the bacterial side; mycorrhizae handle the fungal partnership.
• Volcanic rock dust on the bed before drenching. Microbes need minerals to function, and basalt is the simplest way to provide a full trace spectrum.
• Humic acid added to the ferment, or applied to the bed afterwards as a long-term carbon substrate.

A few honest caveats

1. It varies by location. Your leaf mould is a wild inoculum. Two batches from two woods will differ. That is part of the appeal: you are cultivating microbes adapted to your exact climate. It does mean results aren’t perfectly repeatable.
2. The salinity claim is contingent. Cho says JMS reduces soil salinity. The mechanism is plausible: microbes take up sodium and chloride into biomass. There is little independent peer-reviewed evidence for the effect at field scale, though. If your soil is heavily salt-loaded from de-icing or coastal spray, address the cause; don’t expect JMS alone to remediate it.
3. Don’t apply at full strength to seedlings. JMS is a strong biological dose. Stick to 1:10 minimum on anything younger than four true leaves, and 1:20 on early seedlings.

Frequently asked questions

What is JADAM Microbial Solution?

JADAM Microbial Solution (JMS) is a low-cost microbial inoculant made by fermenting forest leaf mould with a boiled potato in salted water for one to three days. The leaf mould supplies the microbes; the potato feeds them. The result is a bucket of indigenous soil organisms ready to drench across your beds.

How long does JMS take to brew?

One to three days at 18 to 22°C. In summer it can finish in 24 hours. In a cold spring it may need three days, or a heat mat. The signal that it is ready is a continuous “raft” of foam across the surface. Use within 24 to 48 hours of the raft forming.

Where do I find leaf mould?

Below the layer of recently fallen leaves under a mature tree, in healthy woodland or an old hedgerow. Brush away the top leaves and you should see a dark crumbly material that often looks like worm castings. Take a small handful from the top inch. Avoid playing fields, roadsides, and any land that may have been sprayed with herbicide.

Does JMS replace fertiliser?

No. JMS is a microbial input, not a fertiliser. The nutrient load from a 1:10 drench is negligible. It works alongside your usual feeding programme by keeping the soil ecosystem active, which helps plants take up the nutrients you do supply.

Why hasn’t my JMS formed a raft?

Three common reasons. The water was too cold (below 18°C and the ferment stalls). The water was chlorinated and the microbes died at the start (always rest tap water for 24 hours, or use rainwater). Or the leaf mould was too old or dried out and the microbial load was too low. Try again with fresh leaf mould from a damp patch of woodland and a bucket sat somewhere warm.

Can I store JMS for next time?

Not really. JMS has no useful shelf life. Once the raft breaks up, the microbes start dying off, and within a week the brew is dominated by whatever survives in a depleted, anaerobic environment. Brew it the day before you need it. The recipe is cheap enough that running a fresh batch is easier than trying to stretch an old one.

Is JMS suitable for organic gardening?

Yes. The ingredients are water, leaf mould, salt and a potato, with optional rock dust, humic acid and mycorrhizal inoculant. Nothing in the standard recipe is excluded by the major UK organic standards (Soil Association, OF&G, Organic Farmers & Growers). It is a foundational input in JADAM organic farming, which is itself recognised by IFOAM Asia.

Is JADAM Microbial Solution the same as EM-1 or bokashi?

No. EM-1 and bokashi bran are bought products built on a fixed culture of microbes, mostly lactic acid bacteria, yeasts and phototrophic strains. JMS is a homemade microbial inoculant that grows whatever already lives in your local leaf mould, so every batch reflects your own ground and varies a little. They work well together: a bought inoculant gives you consistency, while JMS gives you low-cost volume and local adaptation.

Sources

1. Cho, Youngsang. JADAM Organic Farming: The Way to Ultra-Low-Cost Agriculture. JADAM Organic Farming Institute, 2016.
2. JADAM Organic Farming Institute. “How to make JADAM Microorganism Solution (JMS).” en.jadam.kr/news/articleView.html?idxno=8350
3. JADAM Organic Farming Institute. “Introduction to JADAM.” en.jadam.kr/com/com-1.html
4. IFOAM Asia. JADAM Organic Farming for Sustainable Low-Cost Agriculture in South Korea. ideassonline.org
5. Higa, T. and Parr, J.F. (1994). “Beneficial and Effective Microorganisms for a Sustainable Agriculture and Environment.” International Nature Farming Research Center, Atami, Japan.