“The movement to integrate Biochar into our soils must be localized in scale, and by preferably utilizing the waste products of other systems as to ensure any wider environmental damage is minimized.”
Integration of Biochar Into Existing Permaculture Systems – Reducing Carbon Footprint and Increasing Yields
An Integrated Design Research Report by Max Shaap
During the 1870’s large expanses of the Amazon basin were cleared in order to create new agricultural land. Generally, the rainforest soil was poor, low in nutrient fertility and rather acidic thus rendering it difficult soil to work with in agricultural terms. However, seemingly erratically positioned patches of darker and richer soil were found, which became known as ‘Terra Preta” meaning ‘black earth’ in Portuguese.
The reason for their comparatively darker appearance was large amounts of wood char, or charcoal present throughout the profile, holding soil carbon concentrations up to 50x higher than that of adjacent profiles. (J.Jauss, 2016)
These darker soil profiles were able to absorb more water than surrounding soil profiles, decreasing rain run off and erosion, the pH was neutral, as opposed to acidic and maintained a high nutrient fertility, which was not leached even in the heaviest tropical rains.
The Terra Preta was immediately prized by these post Columbian settlements as prime agricultural land, but the formation of these soils defied geological mapping, in other words, they weren’t naturally formed.
To this day (some 145 years later) the exact means of formation of these soils is still debated, however it has become apparent that they are certainly anthropogenic (human made), (J.Jauss, 2016) whether they were created intentionally for agricultural benefit or as a by-product of agricultural waste removal (i.e. burning waste in a shallow pit and covering it with earth) is heatedly debated in the anthropocenic arena.
What is undeniable though, is that these soils create huge agricultural benefits, partially due to their increased soil carbon levels. Benefits that we today may replicate, through the production and application of ‘Biochar’
Organic carbon in soil is a key indicator to soil health and fertility, generally a soil-carbon level of 1.5% is considered the critical level to avoid soil degradation, however this level is generally to low to say that a soil is healthy (C.Freeman, 2015). Worldwide agricultural soils have experienced drastic drops in soil carbon levels due to (for lack of a better term) ‘abusive’ agricultural practices which allow the carbon to be oxidised and returned to the atmosphere as CO2, contributing to the ever increasing levels of carbon dioxide in the atmosphere.
Biochar presents a means by which we may begin to curb the atmospheric carbon levels providing benefits beyond climate stabilisation, in that some of the excess atmospheric carbon is returned to the soil in a stable (can no longer be oxidised) productive form, increasing soil fertility, soil structure, soil water holding capacity and soil biology, whilst decreasing the rate of erosion thus increasing agricultural yields.
What is Biochar?
The distinction between Biochar and charcoal can appear to be a grey area and may appear confusing to new initiates into the world of Biochar.
To adopt the now industry standardised nomenclature first developed by Johannes Lehmann and Stephen Joseph in the 2009 book, Biochar for Environmental Management. Biochar is defined as pyrolyzed organic matter “intended to be applied to soil in farming or gardening or for biological environmental remediation” (A.Bates, 2010) Where as charcoal may be pyrolyzed or torrefied organic matter that is (See below – Pyrolysing and Torrefying) “used as fuel, a filter, a catalyst… or in any other industry or art”. (A.Bates, 2010)
(That means that it is the intent of the production and future use of the ‘charcoal’ that is often the defining factor between Biochar and charcoal.)
The important key fact in the above paragraph is that all the materials considered to be viable for Biochar production are biological, charred plastics (although technically organic compounds), landfill wastes such as rubber tyres or other non-biological materials are not considered Biochar as these materials can become quite hazardous and detrimental in a soil profile and are regularly contaminated with undesirable compounds, i.e. heavy metals.
But that’s not to say that we are limited in our choice of materials for Biochar production, essentially all biologically produced organic compounds (or, Biomass) can be utilized for Biochar production, from waste timbers to excess cane toads. It may be useful to note however, that as the material is destined for the soil to avoid using biomass that may have bio-accumulated harmful substances that cannot be ‘driven’ off during pyrolyzation.
Pyrolyzing and Torrefying
A technical definition of Pyrolysis is “the decomposition of biomass in the absence of oxidising agents” in this case Oxygen acts as an oxidiser. (A.Bezanson, 2008) These conditions can be created by an efficient, well-designed burner (see Methods of Production – The Biochar Kilns) generally between the temperatures of 300-650 degrees Celsius.
One of the primary functions of the kiln itself is to not only combust the biomass within, but to keep the reaction devoid of oxygen. As a result the carbon within the biomass is not driven off into the atmosphere as CO2 (because there is no oxygen present to oxidise the carbon) and remains present in the original material forming a matrices of pores (hence the huge surface area of Biochar) whilst the remaining ‘volatiles’ are driven off as a gas or liquid vapour (which may also be harvested as a yield – see Additional Benefits), reducing the overall weight of the material and leaving behind what is essentially, stabilised carbon.
Torrefraction is a similar process, but occurs at a much lower temperature, between 200-320 degrees Celsius (A.Bezanson, 2008) only partially ‘de-volatising’ the material making it lighter and brittle whilst maintaining the overall potential energy content (A.Bezanson, 2008). This process is primarily used to create a fuel with a cleaner burn/low acid content whilst making the material lighter and easier to transport as well as brittle and therefore cutting down on labour in processes such as milling.
Torrefying however does not create great Biochar, as many of the original volatiles are still present creating an inferior product to pyrolysis.
The Benefits of Biochar in Soil
The numerous benefits of Biochar in soil are physical, biological as well as chemical. Starting with its physical structure and huge surface area. As touched on in the above section (Pyrolyzing and Torrefying) a matrix of carbon atoms is the end product of the pyrolysis of biomass, resulting in an extremely porous material. So much so that 1-gram of Biochar (about the size of a pencil eraser) can yield a surface area of between 1 000 000 – 2 500 000 million square centimetres. (A.Bates, 2010)
The benefits associated with such a large surface area begin with microbial inhabitants, providing a huge area for them to live in within a limited volume, additionally the stabilised carbon atoms foster the growth of mycorrhizal fungi, essential for a healthy soil profile.
The porous structure has additional benefits beyond that of microbial inhabitants, in that the water holding capacity of the soil is drastically increased, as a result, even during the heaviest of rain, rate of runoff is decreased (as more water is able to be absorbed by the soil) which in turn leads to decreased amounts of erosion and holds the water available in the soil for plant root up-take.
In terms of the chemical benefits associated with Biochar, a means of pH remediation/control is an important one. As (properly made) Biochar tends to have a neutral pH and can remain stable in soil for thousands of years it provides a long term buffer against soil acidity/alkalinity as opposed to short term conventional methods of pH control such as the addition of large amounts of lime which is quickly washed out of the soil by rain.
Biochar has an incredibly large Cation Exchange Capacity (or CEC) that refers to the “capacity of a soil to hold exchangeable cations.” (Soilquality.org.au, 2016) (Cations are positively charged ions as opposed to anions, meaning negatively charged ions) As many of our desirable nutrients exist as cations this means that by adding Biochar (with a huge surface area with which to interact with these ionically charged nutrients) we decrease the likelihood of nutrients being washed out of the soil profile by rain and instead retain them in the soil.
“CEC is an inherent soil characteristic and is difficult to alter significantly”, (Soilquality.org.au, 2016) thus the addition of Biochar can be of huge benefit to a soil profile with an inherently low CEC, such as sandy soils.
Methods of Production and Inoculation:
The Biochar Kilns
Today there are many commercial models of Biochar kilns available for sale, however with a few materials you may find lying around in your back yard or at the local scrap/metal yard constructing or repurposing your own is not difficult as there is a huge variety of conceptual designs available online.
Dolph Cooke, (affectionately referred to as the char-master) of The Biochar Project, swears by the Moxham burner, developed by the late Geoff Moxham.
The Moxham burner is ingeniously simple, essentially comprising of a cylinder (such as an old metal water tank) open at both ends so that biomass may be fed through the opening at the top whilst the opening at the bottom is placed squarely on the ground (possibly with piled earth around the sides if need be) to deprive oxygen sneaking in underneath.
By correctly feeding the biomass in without smothering the flame a ‘pyrolysis front’ is created, essentially meaning that the flame burns so high that the flame intercepts all entering oxygen before it can oxidise the biomass within.
Biochar kilns are not modern technology by any means, and anyone interested in creating their own is urged to look online at the many varieties available and chose the kiln most suitable for their needs/scale of production.
The Many M’s
The ‘Many M’s” are simple guideline to ensure proper Biochar production
The first of the 5 M’s of Biochar production is crucial to obtaining a quality product, however it is often overlooked.
Fresh cooked, ‘raw’ Biochar is hydrophobic – meaning it repels rather than absorbs water – This is mostly due to the capillary pressure of air trapped inside the micro-pores, coupled with oily hydrocarbon residues that also repel water molecules.
To avoid such characteristics in the end product, end the pyrolosis reaction with generous amounts of water sprayed into the kiln from a hose. Adding water at this stage will create a hot pressurised steam, which will help to force out the trapped air from the porous substance as well as crack and disperse some of the hydrocarbon residues.
Once the kiln has begun to cool down, empty the char onto a sheet of tin metal and continue soaking until steam has ceased. The product is now ‘hydrophilic’ and likely to absorb and retain much more moisture once it is placed in the ground.
To obtain the absolute best quality end product it is advised to saturate the char with a sea mineral and water solution – a product such as Sea-90 is ideal – as not only does the additional alkalinity of the sea salts aid in loosening and dispersing the oily hydrocarbon residues, it ‘charges’ the Biochar with additional trace elements that may otherwise be difficult to obtain.
The 2nd M, essentially involves crushing up the Biochar to maximise surface area, increasing the materials ability to retain nutrients – see CEC – as well as increasing room for microbial inhabitants and making the material easier to evenly mix and apply to the soil profile/compost.
Wait until material has dried, as a moist product tends to clump together making this step more difficult and tedious than it needs to be. Depending on scale of production it may be easiest to place small quantities of material in a metal bucket and crush it up with a blunt surface, i.e. the head of a wooden stake, or in large quantities it may be more reasonable to leave the product on the sheet metal in the afore mentioned step and crush it up with whatever blunt object is on hand.
Feed the crushed material through a fine mesh sieve to collect suitably sized pieces.
Safety Note – A dust mask is recommended during micronization, as char dust can be potentially detrimental to health.
Another commonly used term for this step is ‘charging’. Biochar is not a fertilizer in its own right, that is, fresh or untreated Biochar is empty of minerals and ions (nutrients) and placing un-mineralized Biochar in your soil may even have detrimental effects (see The Importance of Charging and Inoculation) yet, one of the critical services of Biochar is to retain nutrients in the soil profile and to curb the loss of ions from the soil via leaching and/or out-gassing (see CEC).
For a grower who is serious about the productivity of their soil, it would be recommended to get a soil test to assess the current concentrations of minerals in their profile. By judging deficits and excesses one can make the judgement of the best minerals/nutrients to add to their Biochar mix.
Once reliable estimates at the condition of your soil is obtained, mineralising is an easy process, simply blend the now micronized Biochar with sources of the desired nutrients, i.e. rock-dust, compost, Seasol etc.
The more ions you can charge your Biochar with in advance, the more additional and conspicuous benefits the material will have once placed in the soil as well as minimising the nutrients that the char will ‘soak up’ out of the soil after the initial application.
- Microbial Inoculation
Arguably the most important step of the whole process is microbial inoculation, fresh char is lifeless, however “char’s most crucial service in soil is to be populated by microbes.” (D.Yarrow, 2014)
The intent is to encourage and establish a soil food web of interactive organisms, which do most of the hard work in terms of nutrient recycling and soil fertility cycles.
Again, as with mineralization, placing un-inoculated Biochar into the soil profile can create initial drawbacks of plant available microbial colonies (See The Importance of Charging and Inoculation)
The “First challenge is finding colonies of effective microbes to deploy in soil. Most agricultural soils are badly disturbed, often largely lifeless, so microbes must be outsourced.” (D.Yarrow, 2014) or ‘bred’ in a healthy compost pile.
A number of inoculation methods are available; the most common methods are inoculation via composting and inoculation via compost tea.
Inoculation via Composting is a simple, yet slightly lengthier process, as it requires lengthy maturation. (minimum of 3 weeks) To do so simply place the Biochar into your compost heap and turn it in ensuring it is well mixed, from here the microbes present in the compost will begin to inhabit the Biochar resulting in a well inoculated product ready for integration into the soil. Inoculation via composting also has the additional benefit of ensuring that the Biochar is well charged, or “mineralised” as the char will react with any available minerals present in the compost.
It is worthwhile to note however that “Commercial compost is often poor quality, incompletely digested, with inferior, unbalanced, unstable microbial cultures” (D.Yarrow, 2014) and as such is not recommended for Biochar inoculation, the compost used should be good quality compost, preferably built on site to ensure the inhabiting microbial colonies are suited to the climate.
Inoculation via compost tea is a faster method (however brewing compost tea requires an existing source of healthy microbial colonies, such as worm farm castings/good compost or preferably both). To do so simply place the Biochar in a porous bag or sack and allow to soak in the brewing compost tea for at least 48 hours. Again this process encourages proper ‘charging’ of the Biochar, as it will attract any ionically available minerals in the brew.
Again, a frequently overlooked yet important step, maturation is to leave the now charged and inoculated Biochar to ‘mature’ over a certain time frame as to ensure there is no initial drawback of plant available nutrients or microbial colonies after initial application. (See The Importance of Charging and Inoculation)
Maturation is addressed in the above step where we leave the Biochar to ‘mature’ in the compost pile/compost tea.
Alternatively the Biochar may be added to the soil in the autumn giving the material some months to develop and ‘ripen’, being ready to deliver benefits directly to new plant growth in the spring. (D.Yarrow, 2014)
The Importance of Charging and Inoculation
“Fresh, raw charcoal tilled into soil can retard plant growth the first year” (D.Yarrow, 2014) as the Biochar literally ‘soaks’ up the available minerals and the microbes make a rush from the root zone to inhabit the micro-pores of the Biochar, rendering both microbes and nutrients in an un-plant available form.
This is why charging and inoculating are so crucial, as an already ‘full’ Biochar placed into the ground cannot absorb any more available elements out of the soil profile but rather serves as a store of microbial inhabitants and a slow release fertilizer as the minerals held therein become available to probing plant roots.
Methods of Application and Integration into Existing PC Systems:
Recommended application rates can differ widely with varying soil types and crops, at the present time there is insufficient field data to make general recommendation. (Dr J.Major, 2010) However major studies have been successful in showing positive effects on crop yields with application rates varying as much as from 5 tons per hectare to 50 tons per hectare (500g per square meter to 5kg per square meter). (Dr J.Major, 2010)
As we can see this is a large variable and general recommendations will be subject of further field tests and extensive research on varying soil to corresponding Biochar application rates.
There are a number of viable options to integrate Biochar into existing PC systems, the direct method of application being the simplest, yet arguably most labour intensive. This involves either turning/mixing the Biochar into a compost heap before being applied to a soil, or scattering the desired proportion of Biochar directly onto a bed and forking it into the soil.
Another method of integration into Permaculture systems is that of ‘Livestock Milkshakes’ (a number of tested recipes available online), which involves adding Biochar to the livestock, feed.
“Research in several countries in Asia, Australia, Europe, South America yields consistent evidence that feeding char to livestock improves digestive efficiency, health and productivity” (D.Yarrow, 2014), when this manure is added to the soil now containing fully charged and inoculated Biochar (as a result of animal processing) that fertilizes the soil as well as neutralising odour and fly infestations. (D.Yarrow, 2014)
Another Permaculture ethic is to obtain multiple yields of a single system and to ‘stack functions’ in time and space. This can be easily achieved with Biochar production as Biochar can be seen as a secondary yield to the primary function of producing heat. Today there are many ingenious Biochar kilns available online which allow you to produce heat to cook/process food, obtain Biochar as a secondary yield and even charge your phone with otherwise unavailable heat energy.
Even more yields may be asked when producing Biochar via Pyrolysis as char itself is only the ‘solid yield’, properly designed production of Biochar can also produce a liquid yield, in the form of tar, heavy hydrocarbons and water, as well as a gas yield which may be condensed into many valuable bio-fuels. (A.Bezanson, 2008)
Biochar: Application of Permaculture
Principles and Ethics:
Principle 2: Catch and store energy
Catch and store photosynthetic energy in the form of carbon, which benefits soil microbial diversity (see Principle 10) as well as contributing to a decline in atmospheric co2 and returning it to the soil
Principle 5: Use and value renewable resources
If the material is sourced wisely and ethically (see potential drawbacks) then Biochar is indeed a valuable beneficial material that may be sourced from renewable resources, contributing to principle 6: Produce no waste.
Principle 6: Produce no waste
Many forms of excess biomass may become waste products on a farm and may even contribute to a raised risk of potential hazard, i.e. fire risk. A way of turning this excess, or waste biomass into a valuable resource is to turn it into Biochar, thus removing the hazard or aesthetic eye sore and repurposing it towards a productive purpose.
Principle 8: Integrate rather than segregate
By integrating the many systems of a hypothetical property, Biochar represents a means of turning the waste of one system (see Principle 6: produce no waste) into a valuable resource in another system (or even returned to the original system) thus integrating the two in an efficient and sustainable manner and valuing the ‘law of return’.
Principle 9: Use small and slow solutions
Rather then clear felling forests for rapid and industrial Biochar production (see Potential Drawbacks) the localised production of ethically sourced Biochar from waste biomass would indeed be a comparatively small and slow process.
However with each successive season the overall soil fertility would increase with minimal, or no, detrimental side affects to another system.
Principle 10: Use and value diversity
One of the main benefits that Biochar offers, is the boom in microbial life and diversity than can be associated with correct application. By valuing the species rich abundance that correct application encourages, soil fertility is increased.
Additionally, when a diverse range of otherwise waste biomass is valued, the potential amount of Biochar that may be produced ethically within a season is increased.
Principle 12: Creatively use and respond to change
As a fundamental characteristic of the ‘anthropocenic’ era, we face an unprecedented rate of climate change, majorly contributed too by a rise in atmospheric carbon. A creative way in which we may respond, would be too sequester otherwise atmospheric carbon and return it to the soil in a productive form boosting soil fertility and increasing yields.
Potential Drawbacks of the Biochar Initiative:
There is some critique to the Biochar initiative held by many well-informed researches. This is mostly due to the ‘industrial’ model of commercial manufacture.
In Albert Bates 2010 book ‘The Biochar Solution’ Dr Elaine Ingham (founder of the now trans-national institution ‘The Soil Food Web’) cites that ““we don’t need it, just good soil-building practices could cancel out global CO2 emissions and balance the atmosphere of the whole planet.”
Dr E. Ingham harbours warranted suspicions that once government agencies and/or industrial agriculture see the potential of Biochar it will become a “juggernaut, pushing the soil-atmosphere carbon balance into an overcorrection”. (A.Bates, 2010) and leading to mass deforestation, in that an aggressive global move towards growing crops in order to turn them into charcoal may spell disaster as did “The acceleration of deforestation spurred by the bio-fuels boom since 2003” (Dr M.Ho, 2010)
The concern is mostly due to some prominent Biochar advocate proposing, “500 million hectares or more of ‘spare land’ could be used to grow crops for producing Biochar, mostly to be found in developing countries” (Dr M.Ho, 2010)
Similar propositions were carried out during the bio-fuels boom resulting in “exacerbated climate change by speeding up deforestation and peat-land destruction, loss of habitats and biodiversity, depletion of water and soil, and increased the use of agro-chemicals.” (Dr M.Ho, 2010)
That is the reason, that in this report there is a particular emphasis on adhering to the Permaculture principles and ethics to ensure that environmental destruction in order to create Biochar cannot occur.
The movement to integrate Biochar into our soils must be localized in scale, and by preferably utilizing the waste products of other systems as to ensure any wider environmental damage is minimized.
Biochar is a useful way to remediate exhausted or depleted soil profiles, however it is not an answer in itself, in already fertile soils correct management practices continue to increase fertility cancelling out the need for the introduction of Biochar
To be truly successful Biochar production must be small scale and localised, made primarily from otherwise waste products, to avoid global deforestation in an attempt to return carbon to the soil at the cost of depleting atmospheric oxygen, and to minimise the necessary inputs from petrochemical reliant processes.
However, particularly in Australian soils where soil carbon concentrations have been drastically depleted by agricultural practices, Biochar created from the waste products of other systems represents a way by which we may return stable carbon to our soils, decreasing atmospheric levels in the long run, and increasing soil health, fertility and agricultural yields in an ethical and reliable manner.
Max Schaap: 01/02/2016
Diploma Student: Permaculture College Australia
(A.Bezanson, 2008) Adam Bezanson – Pyrolysis and Torrefaction of Biomass, 2008
(A.Bates, 2010) Albert Bates – The Biochar Solution, New society publishers 2010
(D.Yarrow, 2014) David Yarrow – Biochar for use in soil, Guidelines and Instructions for Growers, 2014
(D.Cooke, 2015) Dolph Cooke, Avachar the Movie, 2015
(C.Freeman, 2015) Col Freeman – Soil Degradation: Another Carbon Story, 2015
(J.Jauss, 2016) Johann Jauss – Terra Preta de Indio, 2016. Cornell University Department of Crop and Soil Science
(Dr M.Ho, 2010) Dr Mae-Wan Ho – Beware the Biochar Initiative, 2010
(Soilquality.org.au, 2016) Cations and Cation Exchange Capacity – Fact Sheets
(Dr J.Major, 2010) Dr Julie Major – Extension Director of International Biochar Initiative, Guidelines on Practical Aspects of Biochar to Field Soil in Various Soil Management Systems, 2010