biochar innoculation

questions about inoculating BIOCHAR for the first time

I just made my first batch of charcoal for turning into biochar to put in the garden in spring. After making the charcoal, I soaked it for 24 hours in slightly acidic water, then drained away the water. Now I am "loading" the charcoal with minerals while the charcoal is moist. I am using some various rock dusts (basalt with humate), azomite, urea, epsom salt, and a little bit of bone meal and greensand.

Basically this moist charcoal is in a large plastic tub and has been mixed with a bunch of these different minerals and I plan on letting it sit like that for a few months..... Then I will make several gallons of aerobic tea with all my microbes-bacteria-fungi, I will mix some flour with the biochar and then pour my "microbe tea" into the tub with the biochar and create a very wet soup. My idea is to then let the biochar sit in this microbe soup for 1-2 days, then add the biochar to my garden bed. Since this is my first time making/using biochar I have questions.

Question 1. does this recipe sound ok? stage 1 load moist charcoal with minerals (not a wet soup, just moist), stage 2 load the charcoal with microbe wet soup and soak for 2 days in the microbe soup before adding to garden.

Question 2. Is it good to be loading it with epsom salt and greensand? in addition to the other minerals I mentioned? I had a concern that epsom salts could be bad for the microbes I plan on adding later?

Question 3. In stage 1, while "loading" the charcoal with these minerals, does it need to be a really wet "soup" with lots of water? or is it good enough that the charcoal first got a good soaking and is now just "moist" and has been mixed with all these mineral dusts.

I'm really glad you started this topic Andy.
I've had a quick look and can't find much information about how people go about innoculating their biochar. I think my soil (compacted acidic silty loam constantly rain washed) could really benefit from biochar, but how to go about creating that nutrient rich starting point is a bit of a mystery. I have to admit, i was going to just mix it in some compost and hope magic happens! Hopefully some people with experience of actually using it can contribute some more information.

Yes thank you Andy!

I am in a similar situation with a twist. The char I have been making this winter is for garden beds that are 500 miles away. My goal is to gather as much as I can over the next few months and mix it in existing beds. Some of my beds have somewhat established perennials and some are new beds that will be mostly anual in a year or two when I move there.  

I will be following along!

Nancy Reading wrote:I'm really glad you started this topic Andy.
I've had a quick look and can't find much information about how people go about innoculating their biochar. I think my soil (compacted acidic silty loam constantly rain washed) could really benefit from biochar, but how to go about creating that nutrient rich starting point is a bit of a mystery. I have to admit, i was going to just mix it in some compost and hope magic happens! Hopefully some people with experience of actually using it can contribute some more information.

That's exactly how I do it.  I mix it in as I'm making my compost, and let it happen naturally.  Do remember that when you make compost, your greens and browns will shrink a great deal, and your charcoal won't, so you can mix in less charcoal than you might think to get a 10% or whatever ratio in the end product.  I also mix charcoal in with my deep litter in my chicken coop and hoop house.  It helps tremendously with absorbing smells and moisture, and when I remove it in a year or so, it gets added to my garden that way.

John Suavecito has a more robust inoculation system, hopefully he will chime in.

Urine can be stored as nitrogen in charcoal or ash. I just made a lot of leaf charcoal yesterday. I would add as much urine and spit, as they do help conserve moisture by increasing conductivity, add N with urine. If you are in a dry area, I would understand that less urine maybe used, thus less salt, but if in wet region, you shouldn't need to worry about salt.

We inoculate the char sifted from our wood stove ash with pee. Once we get a good bucketful of the char, we add the pee and let it sit in the liquid for several days up to a week. There is very little odor because the char soaks up the urea. Even so, it's kept in the garage. The ash is used as a traction aid on our icy/snowy paths and doorways. There are many other uses as well.

After the char/pee has soaked for a while, I dump it out into the garden beds. Not all in one spot, and since there is still liquid in the bucket you have to be careful not to splash on yourself.  If you do, the dogs and cats will find you fascinating.

We usually do this over the winter since that's when we have the char available. Depending upon your soil type, adding other nutrients to the soaking solution should be fine. For us, it's a matter of what's available and needed for our garden to improve. Good luck with your experiments. I'd like to hear how it works for you.

I've never really seen much point in complex inoculation recipes. The point of biochar is that it persists for huge periods of time in the soil, and acts as a sponge absorbing and re-releasing nutrients in the soil. I'd rather get the biochar in the soil ASAP and add the other material directly to the garden as needed.

In practice, these days I either make biochar in situ and immediately incorporate it into the soil. Or, if in a convenient location, I will add the quenched and cold char to the deep litter chicken run. They break it up into fine material and do all the hard work of mixing it and fertilising it for me. Low human input in terms of both labour and mental energy.

David the Good has one or two videos on inoculating biochar, from what I recall he fills a barrel with it then adds a bucket or three of pond water and then fills it with rain water (not tap water, otherwise the chlorine in the tap water will kill off all the good stuff).

Trace Oswald wrote:

Nancy Reading wrote:I'm really glad you started this topic Andy.
I've had a quick look and can't find much information about how people go about innoculating their biochar. I think my soil (compacted acidic silty loam constantly rain washed) could really benefit from biochar, but how to go about creating that nutrient rich starting point is a bit of a mystery. I have to admit, i was going to just mix it in some compost and hope magic happens! Hopefully some people with experience of actually using it can contribute some more information.

That's exactly how I do it.  I mix it in as I'm making my compost, and let it happen naturally.  Do remember that when you make compost, your greens and browns will shrink a great deal, and your charcoal won't, so you can mix in less charcoal than you might think to get a 10% or whatever ratio in the end product.  I also mix charcoal in with my deep litter in my chicken coop and hoop house.  It helps tremendously with absorbing smells and moisture, and when I remove it in a year or so, it gets added to my garden that way.

The chicken coop method is my go-to as well. It eliminates the stink and helps the soil. What's not to love?

If I ever get to where I can make large amounts, I'll probably keep it simple by adding the charcoal directly where I'll be planting beans. Legumes don't seem to mind the nutrient drawn-down, and by the time I plant something different a year or two later, the char will have inoculated itself.

I am experimenting between open barrel burns and tin man two barrel retort system. Biochar's qualities fascinate me, and if I can have a big old carbon fit and perpetually improve my soil for hundreds of years very inexpensively. No brainer. Where do I sign up? I can do this myself? Huzzah!!
The next conundrum has been innoculating said char.
I have quail in a multi level tower. I have automotive drip pans between the layers, that I usually fill with a layer of pine shavings. The quail are in the garage, and the weather is getting warmer, and Jack Spriko had it right. If you fed a quail a pound of food, it gives 2# of manure. I don't want the garage to get ripe this summer. So last night, I filled the trays with ground up char. I have plenty of shavings in the compost pile, so a few rounds of char and poo should kick up the pile. I want to incorporate char this Spring in the garden beds. I have David the Good's Fetid Swamp water fertilizers barrel going as well. Soaking the char in this may also be an option. It seems difficult to figure out a good way to marinate the char and be able to retrieve it out of the voodoo juice. Some of my char is ground really fine. This is the coolest and most empowering amendment I have ever dealt with.

Lots of great ideas here. Most of what I use, I have learned from you all on this forum. Many good types of inoculants used here.  One word of caution that I would use is that if you inoculate under water for any length of time, your char goes anaerobic. As Elaine Ingham would say, the anaerobes are the microbes that you don't want in your garden.  What you want are the aerobic microbes. Anaerobic microbes lead to disease.   I inoculate with many good items in a liquid drench, but I soak for a minute, then pour it out.   I use urine, whole wheat flour, ag lime, rotten wood mycelium, rotten fruit, worm compost, regular compost and seaweed.  Compost tea is also great but it's too much work for weekly biochar inoculation, IMO. The chicken poo/compost systems work great because they are low work and aerobic.

John S
PDX OR

I am fascinated by the intricate recipes I see here. Wow. I would love to see the results of that -- I'll bet it's amazing.

I confess I don't have time to get fancy. I make char by the wheelbarrow and crude compost by the cubic yard.

Last year, I had a lots of crude char with more ash than I generally like. I also had several half IBC totes that I was trying to make compost work in, but the drought and heat were either forcing them dry/moldy or anaerobic. So I leaned toward the latter, having nothing to lose.

This and several entirely disgusting rot barrels gave me large volumes of stinky anaerobic soup. Phew! I was using it to soak a bunch of decaying straw bales, to knock down the mold and make sure any traces of "the vile dessicant" had been biologically neutralized.

And then, rather than dump it out, I mixed it into the wheelbarrows of char. I added some local municipal compost, forest soil, a pail of sludge from the bottom of the IBC composters, and soaked the char until it floated. And kept adding more vile fluid until the char stopped taking it up. (It also stopped stinking.) Again, nothing to lose.

A month later, I discovered that a number of squash and other seeds had been scooped up from the rough compost, sprouted, and were growing merrily in my neglected wheelbarrows in the midst of a killing drought. Hilarious! it was too late for them to produce anything but flowers, but to my mind, the plants had spoken.

So perhaps it's not necessary to overthink the problem. Given the raw materials, soil citizens and plants will figure it out for themselves.

Someone I follow on YouTube has been spending a lot of time and energy on their biochar system recently. I remembered that they had posted a video about their inoculation method (aerated compost tea with the charcoal added for 24-48 hours, I recall) but I haven't been able to find it to share. Instead, I have found a short clip of the tank which I've embedded. The video should load at the correct timestamp (4:46).



The compost tea was a mixture of fresh manure and rainwater. It might have had some compost in it too. I'm sure you could also add comfrey, rock dust, woodland soil, LAB or many other things. Crucially, the tea is aerated regularly using a workshop air compressor - simple and effective. The aeration stops the mixture from becoming anaerobic (which is an issue I always have with my compost teas).

You could add the charcoal inside sandbags or nets, like a giant tea bag, to make removing it easy. I just throw all of my charcoal in my (smaller) tank and then scoop it out with a piece of chicken wire which acts as a seize. Eventually I dump out the tea onto the compost heap so any smaller pieces will make their way into my soil that way.

Yes, there are many ways of inoculating, and I think that what you can get easily and inexpensively is a factor.  Depending on what kind of animals you have, what you're growing and who you know, it can vary widely.  Some versions are more complex than others.  I do think that inoculating in an aerobic way is really key, though.  I don't want to be building the microbes of disease, rot and sickness.  If I"m going to put some work into it, I want it to be helpful.

John S
PDX OR

I had a very successful  composted-charcoal  tomato plant experiment last year.

I had just started using charcoal in my compost piles as a carbon source the previous year, and this was the first use.  

First, I make my charcoal by burning soft and hard wood tree clipping on my property and dousing the fire with water after the coal bed builds up.  I'm hoping to get a little "steam blast" action to create more pores and lighten the charcoal.

So, burying the lede here,   I planted a tomato plant in a  1.5ft deep hole completely filled with my compost-charcoal mix. It proceeded to thrive through a drought we had WITHOUT WATERING.   It completely blew my mind.  I woke up every day expecting it to be dead.  But instead it fruited.  Harvest wasn't huge and tomatoes were small, but the lawn around it was dead, dead, dead.

End of season I pulled up the plant and the roots had completely interwoven and penetrated many charcoal nodules  which came up with the plant.  I was surprised just how firmly the plant was hanging onto that charcoal.   So,  I think there's zero argument that the charcoal helped make it a better mix.  The only question is how much of the boost was from water-holding,  nutrient storage, and  symbiotic bacteria living in the charcoal.  I'm also speculating  the charcoal was able to grab and hold water from the brief rain we did have during the drought.

I found a article last year where some university had tested charcoal amendment along side compost and the compost-with-charcoal technique.  They found a 10% yield gain when charcoal is part of the composting process vs just adding it later.

Also, I'm wondering if charcoal is speeding up composting itself.  I'm in Massachusetts, so our our summers get pretty warm.  I process/chop all new greens with a  liter or two of old compost to inoculate it and increase the surface area exposed to bacterial action.  I then cover the batch with some old material.
 Starting in June, a fresh load will be fully composted in 5 to 7 days.  I don't know if that's normal, but it sure seems fast.  I'm wondering if it has to do with charcoal helping with aeration and/or easy carbon source from charcoal dust.

That's a really interesting anecdote, Daniel. I have read in many places that biochar stores 6 times its size in water, so it would make sense. It's nice to see it in real life, not just a hypothesis.  
John S
PDX OR