JADAM microbial solution (JMS): 4-day UK brew

By Joe Barrington, founder of Dr Forest · Published June 2021

Quick answer. To make JADAM Microbial Solution (JMS) at home, stir 4 g of sea salt and 25 g of boiled, mashed potato into 4 litres of rainwater, then add about 3 tablespoons of woodland leaf mould. Cover it loosely, keep it above 18 °C and don't stir. It's ready when a continuous raft of foam covers the top: one to three days somewhere warm, nearer four in a cool British spot. Dilute it 1:10 with water and pour it onto the soil within 24 to 48 hours.

How long JMS takes to brew in the UK

I've made JMS loads of times, and the first time I left it too long. JADAM's brewing times are set for Korean temperatures, and here I found it needs a bit longer. I ran mine for five, and at our temperatures four was probably about right. You just need to watch it, and don't stir it or the raft drops out. It's the only way.

JMS comes from JADAM, the low-cost farming method Youngsang Cho developed in Korea [1]. It's a microbial input and carries next to no feed, so keep feeding as normal alongside it (more on that in my guide to living soil).

The JMS recipe

Cho's original JADAM microbial solution uses four ingredients: water, leaf mould, salt and a potato [2]. Diluted 1:10, a 4-litre batch makes 44 litres of drench, enough for about 4 to 9 square metres at 5 to 10 litres a square metre. To scale it up, keep the ratios: for every litre of water, 1 g of salt, about 6 g of potato and 4 to 5 g of leaf mould.

What goes in a 4-litre batch

Ingredient	Per 4 L	What it does
Rainwater or rested tap water	4 L	The carrier. Tap water left out for 24 hours loses its chlorine; any chloramine stays in.
Boiled potato, blended to a puree	25 g	Starch food for the microbes.
Sea salt	4 g	Cho's mineral addition, about a 0.1% solution.
Forest leaf mould	About 3 tablespoons (15 to 20 g)	The starter culture.
Volcanic rock dust (optional)	4 to 8 g	Not in Cho's recipe. Adds a pinch of slow minerals; my guide to volcanic rock dust explains how slowly.
Humic Acid Granules (optional)	0.4 g	Not in Cho's recipe. Leave it out to follow JADAM.

On borrowing from the woods

Take the dark, damp, crumbly layer just under the fallen leaves of a mature tree in healthy woodland or an old hedgerow. Keep away from roadsides, dog-walking routes and anywhere that might have been sprayed. Three tablespoons is plenty, so take a small handful and leave the rest of the leaf litter where it is. If it isn't your land, ask first.

How to make JADAM microbial solution, step by step

1. Fill a clean, food-safe 5-litre bucket with 4 litres of water.
2. Stir in the salt, and the rock dust if you're using it.
3. Add the potato puree and mash it in well.
4. Stir in the humic acid if you're using it.
5. Add the leaf mould. Hang it in a mesh bag, or knead it in loose.
6. Cover loosely. A loose lid or a tea towel lets gas out and keeps flies and dust out.
7. Keep it warm. JADAM's advice is to warm the water if it's below 18 °C [3]. A warm kitchen or a heated shed usually gives a foam raft in one to three days. In a cooler British spot, expect nearer four.
8. Leave it unstirred and watch for the raft. Once a continuous raft covers the surface, use the whole batch before the foam disc starts to break up [3], which usually means within 24 to 48 hours.

Why the method works

The leaf mould is the starter, and local material is the right choice: a 2024 meta-analysis of 335 studies found native inoculants boosted soil microbial biomass more than imported ones [4]. The potato is quick food. Don't swap it for sugar or molasses: Cho notes that potato and water stays close to neutral, while sugar or molasses turns the brew strongly acidic [3].

The foam raft is your gauge: a few days after it forms, the food runs out and the population crashes.

Keep it safe

A warm bucket of wild soil microbes with food in it can grow the bugs you don't want as well as the ones you do. In compost tea trials, nutrient supplements let E. coli and Salmonella grow from very low starting numbers [5].

• Wear gloves, especially if you have cuts, and wash your hands afterwards.
• Water it onto the soil, keep it off the leaves of crops eaten raw, and stop two weeks before you pick salad leaves, herbs or soft fruit.
• Keep the bucket away from children, pets, ponds and drinking water.
• A good batch smells earthy and faintly sour. If it smells putrid, tip it on the compost heap and start again.
• Never store it. Make it, use it, rinse the bucket.

How to apply it

JADAM's own guidance is to put JMS on heavily through the irrigation in the run-up to transplanting, before roots get going [2]. Gardeners following JADAM usually start at about 1 part to 10 parts water for the soil and 1 to 20 for leaves.

How to dilute and when

Use	Dilution	How and when
Soil drench	1:10	1 litre of JMS in 10 litres of water, at 5 to 10 litres per square metre.
Foliar spray (optional)	1:20	1 litre in 20 litres, with a wetting agent, in the early evening, until it starts to drip. Not on crops eaten raw.
Pre-planting	3 drenches	Three drenches across the two weeks before transplanting.
Maintenance	Monthly	Through the season, stepping up to weekly in the fortnight before flowering or fruit set.

Never use JMS neat on seedlings, and go weaker than 1:10 on very young ones. If you spray it, add a little wetting agent: it lowers the surface tension, so the spray spreads over the leaf instead of beading off.

Where JMS fits

JMS is the homemade cousin of EM-1 Effective Microorganisms and bokashi bran: EM is a defined culture of lactic acid bacteria, yeasts and phototrophic bacteria, and JMS is a wild mix.

JMS and the cultured alternatives

	JMS	EM-1	Bokashi bran
Microbial source	Local leaf mould	Cultured EM blend	Cultured EM on bran
Type	Unaerated brew	Mixed culture	Solid fermented bran
Cost	Pennies per litre	£25 a litre as concentrate; about £1.25 a litre once activated, plus the molasses	About £8 to £10 per kg; Grow-Kashi £16 per kg
Shelf life	24 to 48 hours	12 months	12 months
Consistency	Varies by source	Reproducible	Reproducible

Brew JMS for cheap volume from local microbes. Reach for EM-1 or bokashi when you want a consistent culture that keeps. If you go the bokashi route, my guide on how to use bokashi bran covers the bucket routine.

If you're using a mycorrhizal inoculant, check it's still in date, then work it into the root zone at transplanting and keep it out of the bucket: mycorrhizal fungi need living roots.

A few caveats

Don't expect your bucket to copy the woodland floor. A 2026 study of the related Korean Natural Farming cultures, started from forest, salt marsh and city soils, found a few groups of bacteria and one mould, Rhizopus oryzae, took over, and fungal diversity fell [6]. Treat JMS as one input in a soil-first plan that starts with a soil conditioner such as compost.

Related: EM-1, Bokashi Bran and Grow-Kashi are all in the EM and bokashi range.

Frequently asked questions

Q: What is JMS? JADAM Microorganism Solution (JMS) is a homemade inoculant made by steeping forest leaf mould and a boiled potato in lightly salted water for one to three days. It is the core input of JADAM, the low-cost farming method of Korean farmer Youngsang Cho.

Q: How long does JMS take to brew? One to three days above 18 °C, or about four days in a cooler UK spot, and five is too long. It's ready when a continuous raft of foam covers the surface, so use it within 24 to 48 hours of that and don't stir it once the raft forms.

Q: Is JMS the same as EM-1? No. EM-1 is a bought culture of lactic acid bacteria, yeasts and phototrophic bacteria, while JMS is a wild mix of whatever lives in your leaf mould, so no two batches are quite the same.

Q: Where do I find leaf mould? Under mature trees in healthy woodland or an old hedgerow: look for the dark crumb under the fresh leaf litter. Avoid sprayed ground, roadsides and playing fields.

Q: Does it replace fertiliser? No. At garden dilutions it adds almost no nitrogen, phosphorus or potassium, so use it alongside your normal feed.

Q: Why hasn't my JMS formed a foam raft? Usually the water is too cold (below 18 °C), the tap water still has chlorine in it, or the leaf mould was dry or dead. Use rainwater or rested tap water, fresh damp leaf mould and a warm spot.

Joe Barrington

Founder of Dr Forest in Stockport. Joe formulates and blends his own range of feeds, and stocks other soil products alongside them, including EM-1.

Sources

1. JADAM Organic Farming. Introduction to JADAM. en.jadam.kr
2. Cho, Youngsang (2016). JADAM Organic Farming: The Way to Ultra-Low-Cost Agriculture. JADAM, Daejeon, South Korea. ISBN 9788989220176.
3. Cho, Youngsang (2015). How to make JADAM Microorganism Solution (JMS). JADAM lectures. en.jadam.kr
4. Li, C., Chen, X., Jia, Z. et al. (2024). Meta-analysis reveals the effects of microbial inoculants on the biomass and diversity of soil microbial communities. Nature Ecology & Evolution 8(7): 1270 to 1284. doi:10.1038/s41559-024-02437-1
5. Ingram, D.T., Millner, P.D. (2007). Factors affecting compost tea as a potential source of Escherichia coli and Salmonella on fresh produce. Journal of Food Protection 70(4): 828 to 834. doi:10.4315/0362-028x-70.4.828
6. Thompson, C., Mozeika, S., Paredes, E., Lee, U. (2026). Korean Natural Farming practices are dominated by a limited number of microbes and decrease fungal diversity. Sustainable Microbiology 3(3): qvag033. doi:10.1093/sumbio/qvag033