Shaun from ECHO Asia here. We are looking at developing some rules-of-thumb covering how to use biochar as a soil amendment. I’m scoping up some trials to investigate how different preparation methods (e.g. soaking in urine, co-composting etc) affect plant growth. We are also interested in the financial feasibility of biochar use in soils for smallholders.
For biochar users; how do you use biochar in your soils? We are interested to learn from you! Feel free to share how you prepare it for use in soil, and the results you’ve seen!
If you have specific research questions or resources you’ve found helpful, please also feel free to share!
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Thanks for tagging me and asking. I’ve used 5 gallon buckets of local made charcoal, and also local made biochar. I mixed in guano de isla (bird poop from birds who’s diet is pure fish as they’re isolated on an island, so they claim the guano is the best in the world) and urine and sealed the lid on tight and left it there for a long time. I’ve used one bucket but I have some more that have been soaking for years. I wish I had some better organized data for you, but from my observation it has helped enrich our compost and soil. We have more Katuk than we can handle, moringa, tomatoes, and other fruit trees. Thinking of it I might try to put in near my banana trees and put mulch on top of it, as I need to use these last 2 buckets somewhere.
I’ve sprinkled it in about a 1cm deep on top of my soil with either grass clippings or leaves over it. I’ve also mixed some into my compost.
To clarify, at first I didn’t have biochar so I just crushed up charcoal and soaked it as mentioned, and I know it’s not as good as biochar but I believe it still has helped. The biochar has more potential but is harder to procure (I’m too busy to actually make it) so I probably won’t get much more of that as my source is gone.
For reference I’m in a tropical area in the jungle region. There are so many ways to enrich the soil, biochar is just one of them. I’m also tesing hugelculture, banana circles, thick mulching, composting with the help of ducks and rabbits, watered down urine, compost toilet, green manure cover crops, burying dead animals, etc.
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Howdy folks!
I have been making biochar (or to be honest, probably more accurately, its charcoal) in a hole dug in the ground. I live in a very impoverished jungle region where access to materials is extremely limited due to the remote nature of the area. My goal is to create agricultural methods that can be replicated by the local population. The only tools that I use are the shovel to dig the hole and a chainsaw to cut downed trees into appropriate sized pieces. Maybe biochar made from a more high-tech method of pyrolysis is preferable but I don’t have access to the materials to make a system for that and my neighbors certainly don’t. So, that’s why I use a hole in the ground. My opinion is that the difference is probably not that great.
There are several keys that i found to maximize effeciency of this method.
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My hole is 2.5 feet deep, 3 ft wide, and about 5 feet long. This seems to work well but I haven’t experimented much with other size/shape holes. I think it probably is best determined by the size and shape of the material that you are burning. eg. if you are burning coconut husks, a round hole would probably be the most efficient but i mostly cut lengths of wood to about 3 feet long.
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cut the wood to the same size and use material that has the same moisture content, this will ensure that the wood burns at the same rate. An even burn ensures that all of your wood will, more or less, reach the point of doneness at the same time. If some of your wood is really dry and some is very green, half of your batch will be crumbly, black, and ready to extinguish, and the other half will still be actively burning.
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start a small fire in the center of the hole. When, the wood has all charred to black, put on another layer completely covering the first layer. Repeat this process until then hole is completely full. wait until it has all burned down to black that will easily crumble when you put a shovel into it. there should be no flames visible. If the majority of your wood has converted from black to grey ash, you have waited too long! Vigilance is needed! Completely extinguish the fire with water, use more water than you think you need!
The next day, get in the hole with the shovel and grind it up into the smallest pieces that you can, the smaller the better! Pay attention, If it doesn’t want to break in to small pieces it should have burned longer. It is then ready to be activated with some sort of nutrient source.
I have used a variety of different methods to activate the biochar. I most commonly use bat guano because I can get that for free from local caves. I have 5 smaller holes that i use to mix the biochar with the bat guano and i then leave it in the holes for at least a month. Im not totally sold on my method for this because I live in the rainforest and my holes often want to fill up with water but I haven’t devised anything better yet. At first i just left my biochar in the big hole and added the guano but it was very difficult to mix evenly like this so i now shovel it out of the big hole into the smaller holes where i can be assured that all of it is being evenly mixed with the guano.
I know that my method is less efficient than a more high-tech pyrolysis system because I do create ash. The ash, for me, also is valuable for soil remediation in my very heavy, acidic soil. I have seen the effectiveness of its buffering capacity when applied to the surface around your fruit trees, bananas, or growing beds. I believe (though i confess it’s really only a hunch) that it is best to apply ash every several weeks instead of all at once. I try and store my ash where it won’t get wet and lose its effectiveness before i put it where I want it. I use barrels for this.
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Our use of biochar has been pretty limited, but I will let you know what I can. We work in very acidic soils and we tried doing a trial with different soil amendments for different rows. We tried a lime treatment, and NPK treatment, and a few others. Almost as a lark, we used ground up charcoal in one of the rows. From an earlier trial the use of chicken manure seemed to be the most effective amendment, so we used that in all rows. The combination of charcoal and chicken manure seemed to give the best results but since we had an insect infestation it is a little hard to know for sure as the yields in all rows were pretty small. We are going to try to redo the trial, and see if the charcoal/chicken manure combination really does yield the best results.
Hi there,
We live in Fiji in a tropical rain forest climate. I have started to make biochar using a TLUD kiln. I inoculate the biochar using Lactic Acid Bacterium (LAB) Culture and Bucket Organic Matter Fertilizer. I’m applying it to my garden beds with compost and then mulching heavily, leaving it for at least 1 week before planting. I’m also going to try applying around our bananas and fruit trees. I’m interested in learning about how others are using it and their results
Thanks for sharing @Jeffrey_Miller . We’d be interested to hear how the follow up trial goes!
Thanks all for your ideas!
We are just starting a small trial at ECHO Asia on use of biochar as a soil amendment. We are looking at the growth rate of mustard greens (Brassica juncea) grown in pots with three different growing mediums. These are, local soil, local soil and 20% uncharged biochar, and then local soil and 20% biochar soaked in cow manure tea. We are making the biochar from bamboo, pyrolyzed in a TLUD kiln.
We’ll let you know the results!
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I have been trying to teach myself about regenerative agriculture methods for several years and recently started researching biochar. I have previously built a Johnson Su bioreactor for high fungal to bacteria vermicompost (Beam) and have some 3 year old agroforestry rows. I currently have very sandy soil (near the beach) and routinely have larger tree pruning branches and infected leaves available that I think would be a good match for biochar. I see many comments about inoculation ranging from not required to very specific mixes. Some early analysis done by Dr David Johnson the developer of BEAM demonstrated that plant growth is controlled by fungal/bacteria ratio rather than N,P.K or SOC. I wonder if BEAM extract applied to biochar would give similar yield results. The BEAM method seems much more cost effective for large scale agricultural use than biochar.
Other thoughts that I had are:
- How much should be used in a potting mix (replace coir, vermiculite or peat)?
- Should you generally broadcast on open areas and integrate to what depth?
- Is there a minimum application amount that is required to be effective?
- Is it more effective to apply around the tree drip zone or beyond in either pockets or continuous line?
- How much biochar should you make in a greenhouse (polytunnels) in cold climates?
- Alternatives for biochar co products to improve carbon efficiency.
Are you familiar with Dr. Johnson BEAM work? Message me if you want more information.
Thanks for sharing your experience and questions @Chris_Broughton!
For the benefit of other readers:
There’s lot of good research out there on biochar that answer your questions in part. A brief response here, but some google searches on those questions might pull up useful info for you.
Due to the variable properties of biochar depending on biomass type, pyrolysis conditions, and post-pyrolysis processing, there are not really any good rules of thumb around how much to use.
Most research has been done with quite high application rates - around 10 or 20% of soil volume for example, or tones of biochar per hectare. The effect size is highly variable depending on all sorts of conditions. In practice, this are are high amounts of biochar to use for most crops due to cost and practical reasons, rather than reasons of soil quality. In general, biochar is more effective when used in degraded, tropical soils as it can improve drainage, water holding capacity, retention and cycling of nutrients, and soil microbial life. From meta-analysis of the research, there is a large reduction in effectiveness of biochar in temperate climates.
Generally, the benefits for soil structure and fertility are most useful for plants if the biochar is in the root zone. That answers in part your questions 2 and 4 above.
It would be great if you could share some of the key points about Dr Jonhson Beams’ work, and any relevant resources, in this channel for all to benefit!
Thanks
Shaun
