According to Michael Low of Green Fire Farm 2 in Vermont, “The easiest method [of making biochar] with common materials is the T-LUD [top-lit updraft] stove . These usually employ a 55 gallon (210 litre) drum and some variety of hardware for drafting and gas flow.” His favorite design is the Hookway Retort, 3 which is simple and easily built with local materials, but many designs have been published. YouTube is a goldmine for additional ideas on producing biochar. 4
Spread pure inoculated biochar about a ¼in (6mm) thick on the soil before normal tilling. Do this at the same time you till in your other soil amendments. It’s that simple. For larger areas such as pastures, the ideal amount of biochar to till or disc in is one ton per acre, but if you don’t have that much, spread out what you have and add more each time you amend the soil.
You can spread pure inoculated biochar around a grow area, then mulch as normal to hold the biochar in place. It takes about 10 pounds (4.5kg) of biochar to properly cover 100 square feet (9.3m 2 ). For potted plants, use pure biochar at a ratio of about 1:16 with your potting soil – about ½ cup per gallon of soil (118ml per 4 litres of soil). This ratio is good for raised beds as well, one gallon (4 litres) of biochar per 16 gallons (64 litres) of soil.
The simplest and most efficient method to biocharge your biochar is to simply mix it into your compost piles, stacking functions to benefit both the biochar and your compost. Even if you buy inoculated biochar, rather than producing it on-site, it will be improved by maturing in your compost. You can use as much biochar as you want, up to about an even 1:1 ratio with the compost, so don’t worry too much about overdoing it.
Once everything is well mixed, insert a long tube such as a length of PVC pipe into the barrel and direct air from a blower into the tube, or use a pond aerator and air stones. Aeration supercharges the inoculant and gives the beneficial microbes a massive head start, and helps them adhere to the biochar. Continue this for 12-24 hours.
Second, they are able to produce inoculant tailored to specific uses. Vermont Biochar, for example, produces (by hand) several versions ideally suited for either leafy annuals, root crops, or shrub or woody perennials. Each uses a different composition of inoculant to tailor it for the specific application.
Even commercial biochar producers say their products benefit from being biocharged again once it’s on your property, to tailor it to your site conditions. Here are two easy methods you can do at home.
Biocharging (inoculating) your biochar will actively accelerate soil recovery and mycorrhizae growth, creating healthier, stronger and more nutrient dense plants.
Biochar has three impacts on soil and microbes: chemical, physical and biological.
Biochar is a form of horticultural charcoal. However, the modern day biochar is formulated to a specific quality standard (eg UK-BBF, EU and IBC quality mandates). These standards not only require the biochar meets a specific chemical analysis, they often dictate that it is made in from sustainable resources using an environmentally ‘clean’ processes. M odern biochar retort kilns reduce the harmful emissions over traditional charcoal ‘ring’ kilns.
It depends on your soil tilth, aggregation, nutrients, pH, texture (sand, clay, humus), and what you are trying to achieve! The range is 0.5-5 Kg/m2 (5-50 t/ha), around 1-10% by volume.Heavy clay soils tend to benefit from higher application rates.
For the very best results, we conclude biochar should have the right pores present AND accessible to microbes for microbes to inhabit. Small fragments ( International Biochar Organisation
The biochar industry is young with many research projects still underway looking at many different biochar formulations – everything from a super high surface area “activated carbon’ down to brown-char (partially burnt wood). Working with SoilFixer, we can offer a range of biochars:
- Inoculate (charge) biochar with various items such as nitrates, urine, NKPs, trace minerals, rock dusk, AMF, specific root fungi (eg RootGrow™)
- Mixtures of biochar with compost
- Various crushed and sieved grades from 0-25mm (eg 2-8mm, Kon-tiki has been proven an exceptionally clean burn – it is, therefore, a huge step up from traditional charcoal production methods (clays and ring kilns). Our R&D Kon-tiki kiln does not have any heat recover, but when we move into our new premises our goal is to fit a heat recovery unit. On balance, Kon-tiki kilns have been approved for small scale biochar production.
Our logic (supported by our testing) is as follows:
Perennial plants – 500g of char should be sprinkled into the planting hole alongside a mycorrhizal inoculant (eg Root Grow) before backfilling the hole with soil.
Add biochar to soil and compost to improve:
What is it made from, how to activate, how to use it to improve compost and top soil. SoilFixer advice and range of biochar products available online shop.