3.4.8. More Soil Building Techniques

Biochar

Biochar (wood charcoal) is added to soils to store nutrition, water and other beneficials, and to create a stable particle that can help them build and stabilize. It was discovered that indigenous people in the Amazon used biochar to enrich their soils and it enabled them to build very fertile, permanent soils in a place that was usually poor in nutrients.

Biochar is just one of the key ingredients in this mix. Also found were other elements often found in good compost like bones, seashells, food waste, and manure. This combination made a rich, stable, permanent soil called “terra preta” or “black earth.”

Biochar is a key ingredient to this stability because when wood chars, it becomes a stable carbon molecule. Wood breaking down can offgas carbon, but when burnt, the molecule stays where it is. Burning removes organic oils and leaves the pure carbon, which ends up forming a sort of cavelike matrix.

Biochar has incredible amounts of sides where each offers numerous niches/homes for living things and nutrients.

This provides a home for the various elements that good soil needs in order to aggregate - a structure to aggregate around, a place for microbes to live, and for water and nutrition to be stored. Biochar acts like a slow release fertilizer that can store things in good times, and release them in bad. It also offers a tiny structure that can form aggregates, particularly important in sandy soils.

Sand is too big a particle to easily form aggregates - clay is a much better size. The theory is, biochar can replace the function of clay where it is missing. This area is being studied with great interest by a lot of people.

We’re doing our own experiments on our farm on this topic. There are many questions as to just what it will take to produce permanent soils in Florida sands, and if biochar can help, how much is needed for various ecosystem, and what else along with it. We’re looking forward to getting more and more answers in coming years.

You can purchase biochar or make it. This is a vast subject that holds much potential because of the relatively permanent carbon capture potential, as well as the permanent soil that it can build. It isn’t a panacea - it is more useful in some soils and climates than others.

We make biochar with wood chips but any organic materials can be used. There are several examples below, using different materials.

The basic theory of biochar is to burn wood while reducing oxygen. This is called pyrolysis. It causes the wood to char instead of turning to ash. This charcoal is a very stable carbon molecule that has a large storage capacity for moisture and nutrients.

Some people are creating biochar units that capture all the gases released from the wood and burn those gases as fuel. Versions of these, called wood gasifiers, were used to run vehicles in WW II when petroleum was being used mainly for war efforts. There is a large biochar unit being produced in California that produces up to 27KW of electricity and small camping stove versions that can charge your cell phone.

Dr. Jim Amonette, biochar expert: “Roughly half of biochar’s climate-mitigation potential is due to its carbon storage abilities. The rest depends on the efficient recovery of the energy created during pyrolysis and the positive feedback achieved when biochar is added to soil. All of these are needed for biochar to reach its full sustainable potential.”

We’ve worked with one of the top biochar experts in the world, Albert Bates, who wrote “The Biochar Solution.” Per him and other experts, making biochar in a two part enclosed container, capturing the gases and using them for fuel, is the most carbon and energy efficient way to do it.

Another pretty efficient method is a “cone pit.” We’ve included instructions for both below as well as one way we’ve burned many gallons, in a single drum.

These instructions are in three parts:
Ways to make biochar in homemade containers
A way to make large amounts of it in a pit
How to “charge” it in preparation for using it in the soil, and why.

Drum versions

Making biochar in containers means you can control the flame better on windy days and can walk away during the burn. It is usually done in about 1-2 hours. There are many different methods of building this drum and most of them work pretty well. We have usually gone with the simplest version.

This explains the theory and some details about methods used to build larger units.
http://edis.ifas.ufl.edu/ss626

Single barrel TLUD or Top Lit UpDraft gasifier

By burning wood from the top down, oxygen is limited, woodgas is used as fuel, and the result is charcoal. This is the simplest version of a biochar barrel burner I’ve seen. We’ve used something similar to this with success. We use wood chips as the medium and burn from the top down. https://www.youtube.com/watch?v=YIbGkmt1VdE

Two barrel retort

This is the simplest version of a 2 barrel system I could find (more efficient burn than a one barrel version). 2 barrels is the recommended version. 
https://www.youtube.com/watch?v=svNg5w7WY0k

This 2 barrel cook stove can be scaled up to a 55 gallon drum, but also makes a great outdoor stove for regular use
http://www.instructables.com/id/Durable-Biochar-Producing-TLUD-Camp-Stove/

Other versions, cone pit

Some people have created metal versions of this. The dimensions can make a difference in the efficiency of the burn.

There are biochar burners that can capture the syngas and make electricity from it. This is more complex than most people want to go but instructions are on the ‘net if you are interested. Here is a manufactured version: 
https://www.bioliteenergy.com/products/campstove-2

This cookstove can be scaled up to a 55 gallon drum, but also makes a great outdoor stove for regular use.
https://permies.com/t/8367/top-lit-updraft-TLUD-wood

More detailed version of a biochar cook stove.
http://www.instructables.com/id/Durable-Biochar-Producing-TLUD-Camp-Stove/

This video is made by John Rogers from Central Florida. His method is more complicated than necessary, but worth watching because he creates biochar in volume and has seeded his property with 2 inches of char. His trees are very productive. He also explains a fair amount about the whole idea.
https://www.youtube.com/watch?v=dqkWYM7rYpU

Gasifier biochar maker. You have to keep adding fuel, this is not as efficient as those that have all the fuel they need, but an interesting, efficient design that I haven’t seen. 
https://www.youtube.com/watch?v=nQxIXDo-egA

There are many ways to create biochar. Some of them are not very efficient and use a lot of fuel to get to the char. These also put out a lot of pollution, both CO2 and toxic particulates, which is why we emphasize the advantages of aiming for maximum efficiency.

These are the substances that can be given off by burning wood. 
https://www.researchgate.net/figure/CHEMICAL-COMPOSITION-OF-WOOD-SMOKE_tbl3_5226126
http://ethoscon.com/pdf/ETHOS/ETHOS2017/BakerandTaylor1.pdf

The more efficient the burn, the better. Again, the two barrel version is most efficient, per the literature thus far.

Grinding char

To maximize the access nutrients have to this biochar edge, it’s good to crush it into tiny particles. The best particle size is very small, dust or sand size. This provides the most edge for the char to interact with other elements to build soil.

There are a number of ways to grind char. Some people wet it down first as this keeps the dust down. We place it on a tarp, throw the top of the tarp over it, and run it over with a truck. People make their own low tech grinders, use garbage disposals, coffee grinders, farm grinders, and other approaches.

Wet it when using a grinder - much less dust. Note that grain grinders are terrible at grinding biochar. Here are a few ideas to get you started: https://permies.com/t/53624/grind-biochar-quantities

Charging biochar

Because of the vast cave network biochar has, it can act like a vacuum and sucks up available nutrition in compost or soils if distributed on garden beds in plain charcoal form. Thus, we “charge” it first, by adding nutrients and giving them time to saturate the char. Then, instead of leaching nutrients from the system, it starts providing nutrition immediately.

There are many ways to charge biochar, including peeing in it, mixing it with manure, adding it to the compost pile, or mixing it with organic fertilizers and minerals. Indigenous Amazonians added many forms of organic material and minerals to charcoal, creating a rich, permanent soil. Note: Because of the intricacy of the cave systems, the char can take 2 weeks or more to charge.

1. Add water plus any of the following to your biochar, in up to 1 to 1 ratio (biochar should never be more than 50% of material).
2. Compost
3. Manure
4. Fertilizer (fish emulsion, seaweed, etc) and rock minerals
5. Urine
6. Bedding for animals
7. Mulch

Compost toilets

Human pee and poo are packed with nutrients and beneficial bacteria that plants need. Yet, we end up sending this precious fertility into places where it could do more harm than good.

Yes, we don’t know what is in the human waste that goes into city sewage systems. But we do know what is in our own waste. It makes a lot of sense that we would include our own “black gold” and “liquid gold” into the circular system that supports us with so much abundance.

“Produce no waste” is a key principle of permaculture, and we know that all “waste” is “food” for something within the ecological system. But one reason people don’t want to deal with it is because of the disease vectors. Pathogens in human waste are responsible for many diseases and deaths in countries that don’t have good sanitation. So how can we handle human waste safely and efficiently?

There are a few things to understand about waste.

Pee doesn’t have the pathogens that poo has. It is free of the dangerous, disease vector pathogens like typhoid and cholera or e. Coli. Those are found in poo. Pee is an amazing fertilizer. It is packed with nitrogen, phosphorus, potassium and calcium. Capturing this important source of nutrients allows us to avoid a LOT of pollution, including lots of drilling and mining for nitrogen and phosphorus sources.

Pee is so fertile, it needs to be diluted to be used, at a minimum 9 to 1 ratio (nine parts water to one part pee).

There are many ways to design a toilet system that separates pee from poo. This is routinely done in Europe and elsewhere, in public and private buildings. Pathogens in poo are killed by temperatures above 145 F, within minutes or a few hours. Human poo can be safely used once pathogens are killed. There are a number of ways to do this.

We use a separation toilet bucket system, meaning separate pee and poo buckets. Pee is safe to use right away, and poo must be processed.

There are a couple of ways to have a pee bucket (actually many, but these are simple and useful):

Pee directly in a 5 gallon bucket or a bucket with a camping toilet seat fixed onto it. Dilute with water, 10-1, and then apply to a fruit tree, raised beds, tomatoes, moringa, etc. Bananas, moringa, tomatoes, peppers love nitrogen and you should see immediate results. Our tomatoes really love pee.

You can also pour the pee on your compost pile. This gets smelly if you leave it for a day or even less, so we keep it covered if we’re going to do that. Peeing directly on trees is ok if you don’t overdo it. Pee is very high in nitrogen and you can actually burn plants if you pee on them too much without dilution. Rain counts as dilution, incidentally. Remember, you need minimally 9 parts water to one part pee.

You can create biochar, and pee into that. Fill a bucket with biochar, and pee into it. There is no odor with this method. When you start smelling it or seeing liquid, it’s full. Cover it, and let it sit for about a month. This allows the pee to soak into the char and become integrated.

You can now pour this onto beds or around trees. Integrate this into the mulch or soil. Do not leave the char on top. It will give much more benefit when integrated into the soil.

You can also pour the bucket on your compost pile. It will enrich the compost and ultimately, with the char, will help you create a beautiful permanent soil.

You can use any “brown” organic material to pee into. We’ve used wood chips, wood shavings, leaves and pine needles, all to good effect. All of these absorb the odor until almost full, at which point you can empty the bucket onto your banana circle, trees, or sheet mulch garden beds that you’re building, and cover with another layer of brown (leaves, wood chips, etc) to protect the nitrogen from the sun and handle the odor. You should not smell anything except when you dump the bucket and then only very briefly.

Rinse the bucket out, fill with brown material, and keep using it. This is a very simple way to capture this wonderful fertility coming from you, and feeding the systems that will soon provide you with lots of abundance in return.

NOTE: We put the toilet paper, if any, in a separate container and compost it. Just makes it easier to distribute the pee. It’s possible to create a “fertigation” system where pee is routed into a tank that can be filled with water, and then sent, through a hose, to trees or beds.

For poo, use a separate bucket. Make sure this is clearly and permanently marked. You don’t want to use it for anything else. Have an additional bucket nearby filled with sawdust, leaves, pine needles, or wood chips. Once you use the poo toilet, cover the material with whatever “brown” material you have collected. There should never be an odor. If there is, you haven’t used enough of the cover material.

Ensure this bucket has a lid that can be kept on tightly and keep this tightly closed between uses. You do not want flies to get in and then fly near food, for instance.

Once the bucket is full, empty it into a food grade, metal 55 gallon drum. Once full, mark the date on the drum and let it sit for at least one year. This barrel should be able to be sealed so that no animals or insects can get inside (such as flies).

Alternatively, you can place the humanure directly around fruit trees if you will not be eating fruit off the ground, there is nothing else edible on the ground, and your water table is not very high, and you do not have flooding that can move the material elsewhere. If all four of these are not in place, then it needs to go in a barrel or other container to isolate the pathogens.

We prefer the separation toilet system as it tends to be easier to control odors, it is maximally useful and can be used right away (pee).

These toilets are in use all over the world, including the US, and people are enriching soil and enhancing food production for themselves and others.

Summary

Soil and soil building are vast subjects. We’ve touched on some of our favorite techniques here. We do use a microscope to check our soil building results, but you don't need that - whether what you’re doing works or not should be obvious by the size and health of your plants.

If you are working on a broad scale project of many acres, we most definitely recommend you get thorough tests on both mineral content, toxic content and live organisms in your soil before you start designing or installing your system. If you’ve already started, it’s still going to pay to do those tests.

Remember, in permaculture, we feed the soil, not the plant. Everything we do to increase the diversity, aliveness and nutrient levels in the soil will make that plant healthier and more resistant to pests and diseases. This section and the water section are well worth mastering and fully understanding, for that reason.