Uses of Biochar in Soil & Composting
Biochar is a type of charcoal or activated carbon made from wood (or other organic matter) using a process called pyrolysis: basically heating wood in the absence of oxygen. The principle use of biochar is as a soil improver. Biochar can also replace charcoal and activated carbon - so there are 1000’s of possible uses of biochar.
Biochar as a soil improver
The principle use of biochar is as a soil improver – it improves soil health and hence crop yield, fruit, vegetable and flower quality. If you are just interested in biochar as a soil improver - you may prefer our more detailed biochar blog post
Biochar as a soil carbon sink (sequestration) technology
Biochar in soil lasts a very long time (100-1000 years). Hence the carbon is 'locked' into the soil. This is known as a soil carbon sequestration technique. We will write more on this in future, for now if you need to learn more follow this link to Dr R Lal (director of Carbon Management and Sequestration Center at the Ohio State University).
Biochar to improve your compost
Small amounts of biochar (1-5% by volume) added to your compost heap will improve your compost and transform it into ‘super compost’. Our detailed article on this topic will launch soon so subscribe for our newsletter or bookmark the blog and revisit in a few weeks.
Biochar as a compost bulking agent
Using biochar (a form of charcoal) as a superior hot composting bulking agent was discussed by Tony Callaghan inventor of the hot bin composting system (UK patent 2496234) in his article on using charcoal as a compost bulking agent.
Biochar plus micronized powders used to increase compost humification
Biochar mixed with micronized powders can be used to increase humus content in composting using the patent-pending SoilFixer Humification Agent.
Biochar as a replacement for vermiculite and perlite
Vermiculite and Perlite are added to soil growth mixtures to help improve water drainage and increase aeration (oxygen for roots). Biochar can not only offer this functionality; it can offer a whole lot more besides – see our biochar blog.
Biochar for use in hydroponic growing systems
There are two uses. Firstly, activated carbon filters are sold for filtering air before it leaves the hydroponic growing tent. Biochar can perform the same air filtering function at a fraction of the cost.
The second use is as a hydroponics growing media. Although hydroponics is growing plants in water, in many cases inert media (like rock wool, perlite, vermisoil) are used. There is a good video on YouTube explaining hydroponics growth media.
Hydroponic growers should be interested in using biochar as an alternative growing media. Biochar holds and releases plant nutrients (it has a good CEC value), supports aeration (via pores) and is sterile. It meets many of the criteria for a good hydroponics growth media.
Biochar as an Aquaponics media
Aquaponics combines growing fish in tanks with using the nutrient rich water from the tanks for growing plants in. A good series of videos on hydroponics can be found at Murray Hallam's website
Fish excrete poo and ammonia into the water. This nutrient-rich water is then channelled out to the water tanks (phonics) with the plant roots in. The plant roots filter out nutrients and freshwater circulates back to fish tank. Fresh fish and fresh veg in one system. Just as in pure hydroponics, sometimes items like expanded clay balls are used as inert growing media in the water tanks. Contact us if you are interested in trying it out.
Biochar as a substitute for peat and other plant potting soil
The world is finally stopping the use of peat as a plant growing medium. Biochar has a role to play in helping reduce peat – new mixes can incorporate biochar and utilise its water retention and aeration properties. It has to be mixed with other items to give a complete soil media.
Biochar (charcoal) as a specialist growth media
Biochar has a range of properties that make it ideal for use in specialist plant growth media (mixes). Here are just some of the niches:
Orchids (phals) - the porosity, nutrient holding, water retention and percolation make it and ideal potential substitute for traditional orchid growth media. If you are a member of one the special interest groups (eg orchid society)
Asparagus - requires deep planting beds (30-50 cm). Deep vegetable beds tend to suffer from compaction (reducing growth) and nutrient runoff into channels. We know from our own tests beds, mixed biochar granules (0-8 mm size) have a dramatic and permanent beneficial effect on tilth. If you are a commercial grower of asparagus and want to do a controlled growth test call us, it might give you the lead on all your rival growers.
Are there other deep-rooted perennials crops that need excellent tilth? Liquorice has not been commercially grown in the UK for a long time - it was featured for a comeback a while ago in the Telegraph. What about rhubarb, leeks celery? Calling all champion vegetable growers – add biochar to your potting and container mixes. We are happy to chat and help you formulate special
Biochar for Trees (arboriculture)
Many people will have seen the BBC Country File program in which biochar was featured as a method to help tackle ash dieback. Bartlett Trees have been pioneering the use of biochar to help with root compaction and generally ‘reviving’ trees. If you are based in the North East, Northumberland and Newcastle areas; Rob & Eddy have expertise in biochar used in trees and forestry
Biochar for plant protection
There are reports of biochar benefits linked to reducing plant pathogens and acting in a biocidal manner. The science to understand exactly what is going on is still at the early stage. It is not clear if there is a definite effect, or if the benefits seen are due to an overall improvement in the plant health and hence a greater ability to defend against pest and diseases.
Biochar as a delivery mechanism for NPK nutrients (fertiliser)
Using biochar as a carrier for NPK and trace nutrients is sometimes referred to as a ‘biochar compound fertiliser’. This paper from J Jospeh describes technical detail of the concept
We can use the adsorption and porous structure of biochar to take up and hold all sorts of nutrients (eg major NPK, minor like Ca, Mg, and trace (eg boron, selenium). Converting biochar into a compound, slow-release fertiliser is seen as a holy grail for a new generation of fertilisers. Imagine a fertiliser that is hard to ‘overuse’, dramatically reduces runoff and leaching loss. The farmer, gardener, plant, crop and environment all win!
We believe this can be achieved using biochar and colloidal humus. Our focus is on working out a method that consistently gives an exact formulation (eg 5-5-5) when the carrier system is biologically active. Any fertiliser company (be that organic or man-made) that wants to get in early and test inoculated and slow-release fertilisers using biochar as the carrier should call us immediately.
Thank you for reading part one of five articles on the uses of biochar. The other articles can be reached via the links at the top of the page.