Charcoal retains the carbon cell structure of plants from which it is made and, when buried, the carbon can stay in the ground for hundreds or thousands of years. Most fertile soil contains charcoal from ancient or recent forest fires and, until the introduction of synthetic fertilisers, charcoal was widely used by cultivators for enhancing the soil. The most remarkable example of soil modified by charcoal is the deep ‘terra preta’ from a previous civilisation in the Amazon that transformed infertile earth into rich loam.
‘Biochar’ is a new term applied to charcoal that is specifically produced for agricultural purposes. It differs from the familiar charcoal used for barbecues or cooking, which is made from wood in relatively large chunks and retains volatiles that increase flammability. Biochar, on the other hand, can be produced from any biological material and the producer should ensure that it is free of volatiles: wood vinegar, for example, is a valuable by-product as a pesticide and if retained in the biochar would hardly help microbial life! Volatiles and ash could also block the entrance to cavities and make them unavailable to moisture, microbes, fungi and mycorrhizae.
Water-holding capacity, therefore, is one of the easiest tests for assessing the quality of a useful biochar because it indicates whether the cavities are open and available. Another indication is the proportion of char to feedstock: a high proportion may indicate that volatiles and ash are retained, adding weight and rendering the char of little, or no, use for soil enhancement. The temperature at which biochar is produced is critical for achieving a high degree of absorption. The cavities give refuge to microbial life that forms a bridge for nutrients to the hairs on plant roots, thus enhancing fertility. It is desirable to mix biochar, before use, with manure, digestate slurry, compost etc. for it to be ‘charged’ and have an immediate effect with plants.
One hope for biochar, therefore, is for increased global food production while permanently enhancing soil. The other hope is that it could help the struggle against climate change.
Carbon dioxide in the atmosphere is mobile. The ‘carbon cycle’ refers to the movement of carbon from sky to earth and back again. Plants capture carbon through photosynthesis then the activity of microbes release it back to the atmosphere; there is about three times as much carbon in soil and plants as in the atmosphere. Over a period of 14 years an equivalent of the entire volume of atmospheric carbon is captured by plants, enters the soil and is eventually released back to the sky. If more carbon can be stored in the soil there will be less in the sky. Human activity is adding a steady stream of carbon to the atmosphere. Oceans have the biggest store of carbon but excess carbonic acid is already a serious problem.
Land has lost carbon since the dawn of history through overuse or harmful farming methods. The Fertile Crescent is an obvious example. Synthetic fertilisers interrupt the carbon cycle and degrade soil by providing nutrients direct to plants. Compaction from heavy machinery is another problem, and rising temperatures are now reducing the ability of soil to retain carbon. It has been estimated that land in the UK may have lost about half its embedded carbon content since the industrial revolution, so there is plenty of scope for increasing carbon in the soil without harming natural systems.
Organic and permaculture cultivation retains carbon in soil. Not much research has been done in temperate climates on further fertility benefits from biochar though, of course, it would also add carbon. Temperatures above 25degC lose more carbon to the air than in cooler climates, giving a greater tendency to desertification. In dry tropical areas the ability of biochar to retain moisture is the first aspect that appeals to farmers, while its ability to improve the structure of soil and provide a haven for microbial life is equally important. Biochar fertiliser is compatible with NPK fertilisers so can be used in a gradual process of reducing the latter in both temperate and tropical areas. In passing it is worth noting that some research indicates soils enriched with biochar curtail the emission of nitrous oxide.
Since the scientific study of biochar is relatively new there are widely differing views as to the part it might play in combating global warming. Much research has gone into some aspects of the technology but there are not many peer-reviewed papers relating￼to the performance of biochar in the soil at significant scales or over a number of years. This makes some scientists, concerned for their reputations, reluctant to include biochar as a major element in their recommendations for climate mitigation, whereas the contribution of trees is fully understood. However, the principles set out above indicate that biochar has a huge potential that should attract government funding unrelated to commercial incentive.
Most commentators on climate change talk about reducing emissions. However, global warming is caused by excessive greenhouse gas already in the atmosphere, so merely reducing emissions will not dig us out of the hole. Carbon dioxide must be extracted. Chris Goodall wrote Ten Technologies to Save the Planet about means to tackle climate change; eight are concerned with reducing emissions and only two are for extracting greenhouse gases from the atmosphere. Biochar is one of these. James Lovelock has said biochar in the hands of farmers around the world may be our only hope. Others suggest it may play a small role compared with prevention of deforestation and extension of tree planting. Then some commentators say that biochar is just one out of may geo-engineering proposals. It is not. It enhances natural processes whereas most others may have very dangerous unforeseen consequences.
Like all major new technologies there are some down sides. If the burial of biochar were to earn carbon credits there would be a commercial incentive to grow monocultures to provide feedstock for biofuels and biochar: taking the food out of hungry mouths to feed the cars of the rich. However carbon credits are unlikely to be approved because of difficulties over accreditation (how much has been put in the ground? how long will it remain? how much has been burnt? how efficient has the production process been? What is the carbon-effect of monocultures? etc.). There is a campaign that relates possible down sides like monocultures with the harmful effects of biofuels. It focuses on unknowns and any published statements that indicate biochar may not always be effective. In this it is amusing to see similarities in arguments used by deniers of climate change over the last decade: the former are on the traditional left and the latter on the right of opinion. However these strident voices may be useful in alerting governments to the need to have a regulatory framework and not leave the process to the outlandish distortions of the free market.
There are many scientific caveats to the above paragraphs but they give an idea of the importance of plants and soil when thinking of ways to increase food production and reduce excessive carbon concentrations in the atmosphere.
Albert Bates, The Biochar Solution, 2010.
BiofuelWatch, campaign group against biofuels and biochar.
James Bruges, The Biochar Debate, 2009.
Johannes Lehman & Stephen Joseph, Biochar Environmental Management, 2009
James Lovelock, Biochar as Solution to Global Climate Change, YouTube, 2009 (video)
6 Replies to “Panel: Biochar by James Bruges”
James, of course charcoal may have the benefits which you outline, but benefits for a few, since the charring process reduces complex proteins to much less than the original bio mass. The total mass of bio is reduced in exchange for heat. Moreover that bio mass is imported from soils, which must thereby lose fertility. There are specialist soil organisms for every stage of decomposition and mineralisation and so plant growth. For instance, earthworms begin the first stages of the bio cycle, which bio char removes. If wastes are returned evenly (& justly) to agricultural land, then they will be spread very thinly indeed, so that mineralization is taken up in plant growth rather than into gasification and leaching.
People have been curious about the high fertility of the Terra Preta soils of the Amazon Basin, which were achieved over generations by the systematic addition of charcoal. Hunting, foraging and fishing had provided a surplus of waste to that of the complementary agricultural production. Charcoal became a useful tool for the storage of that surplus fertility. Such systems are no help to us today. We can only import bio mass by impoverishing a neighbour’s bio mass and we have no
wilderness for foraging.
On a planetary scale, charcoal (or sequestration sump) reduces bio mass for both crop yields and the pumping capacity of Earth’s lungs. Of course elites may import charcoal for
their particular benefit at the expense of the many. It is no accident that the latest “Green” craze is charcoal sold,
(ironically by an “organic” millionaire) as Carbon Gold! It fits a certain market perfectly – seeming technological, while fashionably embracing the wisdom of the ancients!
That Carbon Gold is certified as “organic” by the Soil Association is a measure of how corrupted simple common sense has become. Biology does not follow laws of physics in which matter or energy always remain in either form. On the contrary, life can diminish to nothing – re-appearing as its lifeless components. It can also increase to an optimum mass – a mass which bio char diminishes. The carbon cycle is a delusion. Carbon cannot cycle. Living highly-complex proteins cycle and by way of the very many elements of which they are composed.
Here’s some more – Sorry!
I personally have been using biochar for my own needs in home gardens and orchards for several years. I am quite happy with the results and find the above comment to lack real world flexibility. If biochar (or any true fix) is to make a deep impact on the threat we ourselves are presenting to our world, then it is going to have to be accessible for the average Joe. Speaking in industrial terms, products, importing char, etc. is still living in the mindset from which our problems proliferate from. A common household produces, aside from compostables, enough organic waste convertable to biochar to easily replace the carbon lost around the home. Especially over the years. I may not single handedly be solving the global warming crisis, but on our 1/5 acre lot we are producing a lot of food and taking responsibility for our little corner. The soil here is far more fertile than it ever was as lawn, which we removed, and we are not stealing our carbon from unfortunate neighbors. It is a part of the resource/waste stream of this house already. We are merely capturing it and retaining it in the soil. no additional crops need to be grown here to meet that need, this culture is already wasteful enough to produce all that is necessary. ANY PROCESS THAT OCCURS AT INDUSTRIAL SCALES BECOMES UNSUSTAINABLE. If we continue to act at that level, we will cause harm and lose access to the side benefits that come from any process that is done by an individual or household that can identify and take advantage of incidental byproducts of that process (ie, heat, waste removal, cooking, etc.) Biochar needs to be as accessible and common as composting. Individuals need to educate themselves and act. The degree to which knowledge/data about biochar will proliferate under those conditions will be great. Also, fire is a natural part of most terrestrial ecosystems. It has been gone for too long from most forest and rangelands that were traditionally managed heavily, and sophisticatedly, by First Nations peoples. I believe this would go a long way toward fixing carbon, both into soil, and into faster growing trees (temperate forest fires typically become carbon negative after only 3 yrs due to faster tree growth). Everyone needs to become a conscious part of their ecosystems again or we will continue to cause blind harm.
Patrick. Thanks for your response and the attached article, which I found interesting because you obviously know so much more about nature’s mechanisms than I do. When the use of biochar is driven by neoliberal economics (as with all aspects of life) it has dangers, as pointed out by BiofuelWatch.
This is why I am interested in SCAD’s approach that is based on cooperation and interdependence. For nearly 30 years it has responded to needs and requests from the community, mostly in villages. SCAD also suggests new techniques, which the villagers may, or may not, adopt (organic cultivation, vemiculture, azola, oorani ponds etc.). For example, they are pleased with effective micro-organisms (EM) for dealing with pollution and pathogens. I have known Cletus Babu for about 12 years. When I mentioned biochar for soil amendment a few years ago he was keen to try it. Much of their soil is semi-desert and gives very low yields even though they have been struggling with organic methods. Their first experience with biochar showed that it retains moisture in the soil, halving the irrigation needs of banana crops (and it was fairly obvious that it provides a haven for microbes). Their studies show that about a third of agricultural waste is – or can be – used for composting, so suggest that half the remainder could be pyrolysed. Interest is increasing among their women’s groups and small-scale farmers. And interest will only increase further if it benefits the many, not the few. The IBI has an article about it that you might like to open,
As you can see, this approach can be accepted or rejected by its users based on whether or not it works, not on any belief that biochar is the best thing since sliced bread. Perhaps your criticisms apply mainly to its intervention in temperate climates where it might interfere with organic production (though I see it as a complementary technology to organic methods, certainly not either-or).
I don’t understand your rejection of the carbon cycle. In Wales phytophthora ramorum is affecting rhododendron and larch that are then burnt on site to prevent the disease spreading. Surely this release of greenhouse gas is damaging to the atmosphere? Much better to pyrolyse them – the brushwood in particular (a study by Swansea university shows that clearance of a hectare of rhododendron releases 318 tonnes CO2-e whereas biochar production captures 123 tonnes – I note that you reject the idea of sequestration, though I can’t understand why).
Thanks James – Sequestration & carbon sumps are bees in my bonnet. I’ll try to keep my bees under control – they are confrontational in that they oppose some central first principles of the IPCC, Zero Carbon Britain 2030 and most university departments! A little geezer becomes passionate in proportion to the mass of his opposition.
Firstly I must say that we concur in just about everything but for that founding first principle. For instance, bio char is certainly beneficial to soils. It undoubtedly retains carbon in a stable form, helps water retention and so on. Moreover you are absolutely right in the case of burnt deseased materials.
First principes first. This is the false founding equation used for Zero Carbon Britain 2030 calculations. It is particularly convenient because the coefficient for burnt bio mass can simply be entered as zero! Here it is (from the authors of the report)
“If biomass is burned, the chemistry is more or less reversed, and the original energy and raw material (CO2 and water) are released. There is then no net gain or loss of CO2, which is why biological fuels are considered to be Carbon neutral.”
Every gardener can immediately and pragmatically refute that version of “the carbon cycle”
If we grow a crop, burn it and then return nothing to its soil but gas and ashes, will the subsequent season’s crop yield be maintained? Moreover will the same area of leef be presented for photosynthesis? IPCC & CAT say that they will.
The proposition is self-evidently ridiculous and yet it is accepted over the world by nearly every authority.
I think the problem has risen, because life does not follow laws of physics. The components of life do – they exist forever as either matter or energy – but life can diminish to nothing – re-appearing as lifeless physics. Death is a part of life, but lifelessness is something far more chilling.
Carbon does not cycle. Life (or if you like complex proteins) cycles. Life flows from life to life in the same manner as a river, in that increasing speed, indicates increased mass. Speed (the coefficient of time) has been omitted from carbon calculations.
The speed of cycles can only increase to an optimum mass – that optimum being achieved (I speculate)by the most happy symbiosis of a complexity of functions of a diverse complexity of species!
If we consider speed in practice – of, say a city and its surrounding agricultural land, then we consider the cycles of crop yield and the return of wastes. Cycle too fast (return too much waste to a field)then crop yield rises for that field, but nutrients leach to water courses and gas to the air. This means that a neighbouring field will be short of nutrients so that its yields will fall. The total yield to supply the city becomes less than optimum. So judiscious return of wastes is the whole art not only of husbandry, but also of civic justice.
With regards to climate change and the power of photosynthesis, the same applies. Cycles can increase to an optimum mass – optimum mass is also optimum speed.
To bury living material in a carbon sump slows living cycles, reduces biomass yield and also the pumping capacity of Earth’s lungs. Because climate has been disbalanced by the release of millions of years of sequestered photo synthesis through a few decades, does not mean that we can reverse the process by the reduction of living biomass.
The effect is to the contrary. Of course we must do all we can to keep carbon in soil humus, peat bogs, coal, oil & gas undisturbed, where they lie. But we cannot create such “sumps” ourselves without reducing the mass of life.
Here we go – BIO CHAR sequesters carbon in a stable form and while gardeners may be pleased with the result, it reduces complex proteins to much less than their original state. It reducues both the total mass of bio and the power of its respiration. It pleases some, while removing fertility from others and so, like our example in the inequity of city wastes it is a matter of civic justice.
To fight climate change and also to provide optimum crop yields we (conveniently) follow the same ends – that is to find ways through how we live, trade and farm to live in the most complete symbiosis with the total mass of life. – No fire – no charcoal.
Am I coherent?
Not really. It’s called entropy. The process that reduces complex life to dust. It happens all the time, not just by fire or pyrolysis. ‘The total mass of bio’ is not constant, it continually increases and decreases. By growing biomass in desert sand entropy is reversed.
Blimey James – Sorry to continue the correspondence and please end it if you feel so, but this is important. Life is variable as the quality and quantity of the dust which revives it. The mineralsation of complex proteins into the simple elements required for plant growth is a function of a complexity of life. The whole art of husbandry is regulation of the speed of that process. Return too much fertility to a field and we increase crop yield by diminishing that of a neighbouring field.
The sophistry of desert agriculture falls at the same hurdle as hydroponics and vertical agriculture. To grow crops in a desert we must import nutrients (& water) from a life-cycle somewhere – so diminishing that cycle. Moreover, we will never replicate the complexity and ecological success of that evolved living process. In diminishing a succesful ecology for the increase of a temporal one, we diminish the optimum bio mass yield of the two.
Entropy is a physicists delusion – To suggest that the small yield of ashes from combustion can be equated to the much greater mineralisation of fungi and bacteria is ridiculous. You are stuck in the carbon cycle. Carbon cannot cycle. Life does.
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