Inoculants for biochar charging

Just curious, what is your inoculant?

Combo of urine, whole wheat flour, ag lime, seaweed, compost, rotten fruit, rotten wood, and worm castings.

Whatever you put into biochar as an inoculant will be trapped inside and gradually released over time.
If you use something with a high nitrogen content, it will naturally release nitrogen (bound nitrogen, of course).
Therefore, I highly recommend using a complex fertilizer, such as manure of any kind.

Please note that with this addendum,

I would like to supplement the existing text:Nuance: Why Raw Biomass Fails and What Biochar Actually NeedsTo truly unlock the potential of biochar, we must avoid a common misconception: adding raw, unprocessed biomass—such as flour—does more harm than good.

Biochar will not "respond" to ingredients in their raw form.
Instead, it requires the specific byproducts generated during their decomposition, which is also closely tied to particle size.
Here is why raw ingredients fail and how the process actually works:

1. The Chemical Transformation (Decomposition into "Ready" Nutrients)

The Problem: Materials like flour are complex organic polymers (primarily starch and gluten). Biochar acts as a passive, highly porous sponge; it lacks the biological capability to break down these complex macromolecular structures on its own.
Introducing raw flour directly into biochar within the soil triggers rapid, uncontrolled fermentation.
This process can deplete localized oxygen levels and create an anaerobic, toxic environment for plant roots.

The Solution: Biochar only interacts with secondary decomposition products—the compounds generated after soil microorganisms (bacteria and fungi) have fully processed the raw material. Only when complex carbohydrates are broken down into simple sugars, organic acids, and humic substances do we get the correctly charged molecules that biochar can effectively bind and hold.

2. The Physical Dimension (Particle and Pore Size)

The Problem: While flour particles seem fine to the human eye, they are massive "boulders" in the microscopic world of biochar.
These large, complex molecules physically cannot fit into the biochar’s internal pore structure.
Instead of colonizing the biochar, they sit on the surface, clogging the entry pathways to the inner pores and rendering them useless.

The Solution: Only after microbes "digest" and break down the biomass do we get nanometer-sized molecules and ions. These microscopic degradation products easily migrate deep into the biochar's intricate pore network, anchoring themselves to the inner walls.
This is what creates a perfectly "charged" biochar capable of controlled nutrient release.In short: Biochar cannot absorb raw biomass.
It requires the microscopic, broken-down byproducts of decomposition that are small enough to penetrate its pores and chemically optimized to bind to its surface.

You certainly have a way with inciting dramatic arguments.  

Adding only a large quantity of flour to biochar would be a mistake. We agree on that.  

Some people add only compost tea to the biochar.  That is adding only the microbes and no food for them.

I think that is also a mistake.

You are using a static model to describe something that is quite dynamic.

What we need to add is a diversity of microbes and food for them to eat.

Even during the week that I inoculate the biochar, I can see differences in the volume of the biochar plus inoculant.  It gets bigger at first for a day or so. Then over the next 5 days, it steadily gets smaller.  I think that is because the microbes are eating the food and making the biochar their housing. The soil food web is getting set up.  Some microbes are eating others. Some are eating the excretions of others.  Some are just eating the food. If there is no food, the microbes will die off. That is not my goal.  

I only add a cup of whole wheat flour to the mix.  It is well known as a food for fungi.  I believe that manure is also a good inoculant.  I use "worm manure", also known as worm castings as part of my mix.  

I add a diverse group of inoculants, because I want a diverse soil food web. When they are added to the soil, they are already being digested, especially because it is a liquid form of inoculation.  

John S
PDX OR

Hi John,
Thank you for clarifying your method.
I see now that there was a slight misunderstanding caused by the language barrier and our different approaches to process description.
When I mentioned the physical and chemical limits of the pores, I did not mean a static model in the sense of a dead environment.

After all, my entire 9-year experience with Terra Preta is based on micro-organisms and nutrients. However, as a production technician, I always look at it through the lens of process stability and efficiency.

By the way, have you noticed the scientific descriptions of how plants literally "eat" microorganisms contained in the soil?
I have a dedicated folder with microphotographs of this phenomenon somewhere deep in my archives, though I cannot find it at the moment.
It is truly a fascinating topic.
For instance, this short video beautifully illustrates the rhizophagy cycle, where root tips absorb bacteria to strip them of nitrogen and minerals: https://www.youtube.com/watch?v=akUi3ZmN2J8
Regarding the ingredients: the word "manure" is universally understood, but adding "flour" without specifying the exact quantity can be very misleading for beginners, which is why I cautioned against it.

Furthermore, I must gently disagree with your view on compost tea—a properly made compost tea is never just a carrier of microbes; it naturally contains a significant amount of soluble nutrients, humic substances, and minerals extracted from the compost matrix itself.

At the end of the day, we both want the same thing—a thriving, diverse soil food web. We just describe the engineering of it from slightly different cultural and technical perspectives.

Hi Pavel,
I liked that video.  Yes, all of the eating of microbes, etc., was what I was talking about. Now I think we're both mostly talking about the same thing.  I use compost tea, but on living plants.  That way they are entering a dynamic living system immediately. There is no worry about undernouishing the microbes, or overfeeding them in the delicate actively aerated compost tea.    I know that some people charge their biochar with compost tea, but IMHO, it seems too much work and too easy to mistime the application.  I prefer adding food and microbes my way, because it feels like the microbes will have a more harmonious transition to the living soil conditions.  

Thanks for explaining,
John S
PDX OR

For soil amendement biochar, I inoculate when the quench is down to 90F with Johnson Su compost extract that has been supplemented with fish hydrolysate, rock dust and kelp for a diverse compliment of microbes and nutrients. Sometimes I add some dynamic accumulator weed infused apple cider or white wine vinegar at 1/1500 dilution. This usually gets mixed into new compost piles or layered with aged compost during topdressing. I also add the extract inoculated char to my chicken bedding, which then goes into my Johnson Su compost. For water decontamination or filtration biochar I just use no manure Johnson compost (except worm castings). I am open to learning better alternatives.

I pee on it.

Actually I add it to the compost pile while building it and occasionally - like every morning- pee on it :)

I used to add a lot of stuff, make mixtures, rock dust, minerals all sorts of stuff. I dont know how or why but pee+ biochar works the best. Fungi also likes it.

Compost tea can be a great thing to add to the biochar for inoculation.  My concern is that all of that life will die unless it has food.  It's also a lot of work to make.  If I were going to add it, the best time IMHO is right before you put it into the ground.  Then it is part of a living system, and the positive microbes can go to work in a sustainable ecosystem.  

John S
PDX OR

John, this is why I would use compost extract instead, bubbled while applying right away just to keep it mixed in a 50gal container elevated above biochar pile. Extract is more diverse and resilient than tea, as it has not been adapted to being fed or aerated. I only use tea for foliar applications, as its main benefit is natural glues for sticking to plants (based on my interpretation of an Elaine Ingham paper). The carbon and most nutrients are in the char along with N in the air is abundant microbe food. This also selects for microbes that can acquire these on their own. Charging with Nitrogen will reduce the amount of N fixators, and Phosphorus will reduce P accumulators etc.

I think that it's valuable that each of us is sharing somewhat different methods.   We need to take into account the scale of what we're doing.  I"m just in a suburban lot, so I can't make the biochar on the same volume as some of you can.  Also, there are various restrictions in certain areas: legal, practical, and financial.

John S
PDX OR