By: Rubén Parrilla, Education & Technical Assistance Director

Potatoes are an extremely versatile food – they’re delicious fried, mashed, roasted, boiled, even soaked in water with leaf mold for 48 hours!

Ok, sure – that last idea isn’t necessarily great food for you to eat, but is extremely nourishing for the microbial life in your soil.

In this edition of Be a Better Grower, we’re talking about JADAM Microbial Solution (JMS) and how just 2 ingredients can brew up an amazing biostimulant for your farm.

What does JADAM mean?

JADAM is a term  that means “people that resemble nature,” coined by Korean farmer Youngsang Cho in 1991.He advocates for a low-cost, low-input form of organic management. He also advocates for open information sharing between farmers, and makes his techniques available freely on the JADAM website

What is a biostimulant?

Biostimulants are microbes or other inputs that help spur a plant’s natural metabolism or immune system. Unlike conventional fertilizers, biostimulants do not directly provide the chemical and mineral nutrients that a plant needs.

Instead, they encourage plant activities that support nutrient uptake or the production of protective compounds.

In other words, they support healthier plant growth through a vibrant microbial community in the soil.

Why should I focus on the microbial life in my soil?

If you’re a longtime NOFA/Mass newsletter reader, you’ve heard us talk about soil health again and again. That’s because managing and rebuilding your soil is a crucial step towards growing more – and more nutritious – food from living soils.

A common misconception about transitioning to organic farming is that it takes a long time to return to a conventional level yield. The truth is that simply swapping in organic amendments in the place of conventional amendments does result in a loss of yield.

But if you’re able to simultaneously start working to improve your soil biology – reintroducing micro and macro fauna & flora, like bacteria, nematodes, earthworms, fungi and more – you’ll see yields start to improve quickly.

That’s because the creatures living under the soil do a lot of work to support plant matter growing above the soil.

Microbial activity in compost tea, as seen through a microscope.

For example, microbes help roots fix nutrients and increase nutrient uptake; in fact, microbes sometimes even carry nutrients up through the roots and into the plants themselves before returning to the soil, in a process called rhizophagy. Microbes are also responsible for building healthy soil structure, aerating the soil and allowing for water and air to reach plant roots more easily; a lack of microbial communities is one factor that leads to soil compaction.

Microbial-plant interactions also help support plant immunity – and lead to harvests with beneficial properties for human health as well. Laura Decker of microBIOMETER explains that, in the presence of pathogens, microbes send hormones into the soil and root network. When plants “receive” this hormonal message, they can similarly respond with hormonal signals that fight off the pathogens as part of the plant’s immune response. This plant activity generates antioxidants – which we can then eat to support our own immune systems!

So what do potatoes have to do with this?

The JADAM microbial solution is a means of taking existing soil microbial life, from leaf mold fungus, and giving those microbes an environment to thrive and multiply. 

Keeping the leaf-mold inoculated water covered & warm gives the microbes a comfortable home, and the cooked potatoes provide the right mix of nutrients like carbohydrates, sugars, and vitamins, for the microbes to grow.

After giving the microbes a good environment in which to grow and multiply, you can introduce those microbes to your growing area to act as a biostimulant for your plants.

How to brew JMS

Gather your materials. You’ll need a 5 gallon bucket, non-chlorinated water, 2-3 cooked potatoes, 1 tablespoon (15 grams) of non-iodized sea salt, a stick or dowel, cheesecloth & string to tie the cloth, leaf mold, and a cover for the bucket (such as a garbage bag).

A note on water:

Most tap water is chlorinated, to kill off the microorganisms that can make us sick if we drink them. But we definitely don’t want to be killing any microorganisms in our microbial solution – just the opposite!

If you have access to non-chlorinated water, like well-water or rainwater, use that. If not, dispense the amount of water you’re planning to use, then either aerate it for 20 minutes or leave it uncovered for about 24 hours to off-gas. This should eliminate the chlorine in the water source.

If your water source has chloramine, you should use humic acid (enough to change the color of the water) or citric acid to complex out the chloramine. Off-gassing alone won’t remove the chloramine.

  1.  First, find leaf mold in your area: look for a pile of leaves or sticks at the base of a tree or in a wooded area. You want to use leaves that have a white, powdery substance on them – that’s the mold, and the source of our microbes.
  2. Next, fill a 5-gallon bucket with non-chlorinated water.
  3. Add the sea salt to the water, stirring to dissolve. Place the cooked potatoes and the leaves with mold in a cheesecloth, and tie it closed. Place the cheesecloth potato bundle in the water, and agitate or massage the bundle to break up the potatoes. Massage the cheesecloth until the water is cloudy and the ingredients are mixed.
  4. Place a dowel or stick across the top of your 5-gallon bucket, and securely attach the cheesecloth bundle to the dowel so that it is hanging suspended in the water.
  5. Cover the bucket and leave in a warm, dark place for around 1-2 days. You’re looking for the solution to start to bubble – that’s the sign that microbes are multiplying!
  6. To use the JMS, strain your solution into another container, and dilute at a 1:20 ratio when ready to use. To apply, thoroughly drench the soil in your growing area as often as once per week.

Breaking up the potato bundle is fun for growers of all ages!

Experimenting with JMS

NOFA/Mass’s Soil Technical Services and Education Director Ruben Parrilla loves the simplicity of JMS, and is excited to experiment with tweaks on this base recipe to see how the microbial growth changes.

For example, in his first batch, Ruben added multiple inocula to the mix. Next, he wants to experiment by using a specific inoculum in each batch – for example, trying each of these on their own: leaf mold; compost; grass silage; an IMO3 product (Indigenous Microorganisms 3); and no inoculum at all. He will then use a microscope to analyze the diversity in each batch, to identify the best “bang for your buck” – that is, which brew provides the most diversity with the least amount of work and the lowest cost.

Ruben says his hypothesis is that adding more inocula to one batch is better, to get maximum diversity. But, as the brewing process selects for specific organisms, it could be better to instead brew multiple batches separately and combine them before application.

Ruben encourages others to experiment as well. He says, “I don’t want people to just listen to and copy my process, then feel disappointed if it doesn’t work exactly the same way in their environment. I want to empower people with the knowledge & tools they need to ask questions about the process – what will work for me & my farm? What if I changed the amount of water, or amount of leaf mold?”

Measuring microbial activity

Ruben uses his microscope and microBIOMETER as essential tools for measuring the outcome of different experiments with microbial solutions. Both tools help shed light on the bacterial and fungal growth that occurs in a given soil or solution over time.

For example, below are two microscope photos from his finished JMS:

These photos show the bacterial diversity present in the brewed solution. The food source coupled with low oxygen levels in the JMS process selects for facultative anaerobes — specifically, bacteria that thrive in conditions with oxygen below 6 parts per million.

More Resources

If you’re interested in learning more about using on-farm microscopes and other tools to better understand your soil biology, sign up for these upcoming workshops and webinars – many presented in English and Spanish:

Or, you can also check out the Healthy Soils playlist on our YouTube channel for tons of great sessions on farm microbiology.

Or, if you’re interested in learning more about using a microBIOMETER and manage or own a farm in Massachusetts, reach out to [email protected] to ask about our program that grants farmers a free microBIOMETER kit to use on their farm.

We’re looking for more farmers to participate next year!

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