Guest Post: “Slash and burn”, biochar and REDD in DR Congo and Cameroon

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The claims made on behalf of burying charcoal, otherwise known as “biochar”, are extraordinary. According to the International Biochar Initiative, it will “fight global warming”, it will “boost food security”, and it will “discourage deforestation”. Meanwhile, it is “inexpensive, widely applicable, and quickly scalable”.

One of the most obvious problems with biochar is that vast monocultures of fast-growing tree plantations would be needed to provide the raw material if biochar were to be implemented on a large scale. Peter Reed, an energy lecturer in New Zealand, coined the word biochar in 2005. He reckons that an area of 1.4 billion hectares should be enough. That’s a little more than the total area of arable land in the world.

But there are other problems with biochar, even when it is applied on a small scale. In this guest post, Almuth Ersting of the UK-based NGO Biofuelwatch describes a two-year biochar pilot project in the Democratic Republic of Congo, which is supposed to “replace slash-and-burn farming with a system that uses bio-char”. The post is based in part on research recently carried out by researcher Benoit Anthony Ndameu and Biofuelwatch into a biochar project in Cameroon: “Biochar Fund Trials in Cameroon: Hype and Unfulfilled Promises”.

The video referred to in the post, which is embedded below, was produced by the African Development Bank in May 2011. It provides a fascinating glimpse into the project’s attitudes towards local farmers. Their agriculture is consistently described as “slash and burn” and while the video-makers allow farmers to describe their agricultural system, the “problems” are pointed out by outside “experts”: Vincent Kasulu Seya Makonga from the DR Congo Ministry of Environment and Laurens Rademakers of the Biochar Fund.

“Slash and burn”, biochar and REDD in DR Congo and Cameroon

By Almuth Ernsting, Biofuelwatch

In May 2009, the Congo Basin Forest Fund announced the first and so far only REDD-related grant for the use of biochar, i.e. fine-grained charcoal added to agricultural soils. The €338,000 grant went towards a project in the Democratic Republic of Congo called “Phasing out Slash-an-Burn farming with Bio-char”. The project was initiated by a Belgian-based ‘social profit organisation’ called Biochar Fund, together with a local partner organisation, ADAPEL. According to the Congo Basin Forest Fund’s (CBFF) website, the project will “replace slash-and-burn farming” because biochar,

“maintains soil fertility and constitutes a stable and easily measurable carbon sink. Bio-char thus enriches the soil and makes it more productive, which lessens the pressure to encroach on forest land. Using crop residues to produce bio-char also generates renewable energy in a low-cost manner, and this reduces local dependency on firewood.”

None of those claims have been borne out by scientific field trials. The very limited number of biochar trials shows that different types of biochar have very different impacts on different soils. In some cases, crop yields are raised in the short term, in others they are not affected, and in yet other cases, they are suppressed – longer-term effects have not been researched. Far from being a “stable and easily measurable carbon sink”, field trials show that biochar does not reliably increase soil carbon even in the short term – in one study in Colombia, for example, one year after a high amount of biochar was used on some plots, those plots held less carbon than ones without biochar.

    The Congo Basin Forest Fund was launched in 2008, with a £100 million (around €116 million) grant from the UK and Norwegian Governments. It is hosted and administered by the African Development Bank. The priorities are formally aligned with those set by the Central African Forest Commission (COMIFAC) and three out of five relate to building capacity for REDD and Payments for Ecosystem Services. CBFF collaborates closely with the UN REDD Programme.

The CBFF biochar grant was not only a ‘first’ as far as biochar funding is concerned – it is also the only CBFF grant (and possibly REDD grant in general) to support a technology or practice claimed to sequester carbon in soils. Carbon credits for soil carbon sequestration are one of the aims pursued by the World Bank in Durban and beyond.

So far, the only update from the project comes from a video on the African Development Bank’s website, which is not very informative. The footage shows biochar being produced and spread on soils – there is no indication that it has progressed any further or, if it has, what it has done for farmers, soils and crops. It does however show that promises about producing renewable energy were misleading. The ‘technology’ shown on Biochar Fund’s video is nothing other than a basic charcoal kiln, which cannot possibly capture energy.

While the fate of this DR Congo project is unknown, Biofuelwatch, together with Cameroonian researcher Benoit Ndameu has now published a report about Biochar Fund’s first project, in South-west Cameroon. The reported ‘success’ of this Cameroon project had helped them obtain the CBFF grant for a similar project in DR Congo. According to a Mongabay interview with Biochar Fund’s founding director, Laurens Rademakers, published in August 2010, 1,500 small farmers had been involved/represented in that ongoing project, which, he stated, has increased crop yields on average by 240%.

What Benoit Ndameu found when he visited the area and interviewed farmers, as well as members of Biochar Fund’s Cameroonian partner NGO, Key Farmers, was rather different. At most 75 farmers had participated in biochar trials which had lasted for just one single harvest season in 2009 – and many had dropped out during that season for one reason or another. A brochure handed to them at the start of the trials confirmed that it had always been meant to be a small, one-season trial, but had held out the prospect of a much bigger biochar project funded through voluntary carbon markets from 2010. The farmers who had participated and who were interviewed made it clear that they had been enthusiastic because they were told to expect future income for themselves and their community as well as better yields. Many were still hopeful that such funding would arrive soon – but they had seen or heard nothing from Biochar Fund for a long time. They had given up significant amount of time and labour for free and some had even rented plots for the biochar trials. Apart from one farmers group having made a small amount of biochar to a plot of chilli, biochar had not been produced or used in any of the villages visited since the project had terminated. Farmers had not been shown how to make biochar and in any case Biochar Fund had used one of the cheapest and most inefficient charcoal making methods of all, one in which 90-95% of the biomass is lost.

At the start of the trials, participants had been given hybrid maize seeds and chemical fertilisers as well as the biochar, inputs which poorer farmers cannot routinely afford. Each participating farmer had had to sub-divide each trial plot into 16 different sub-plots to which different combinations of fertilisers, with and without different amounts of biochar were added, and then to separate and deliver the maize taken from each of the sub-plots to be measured and analysed.

If this had been a genuine scientific study, it could have contributed to the still very scant understanding of how different types of biochar affect crops and soils. This opportunity, however, was squandered. Results have not been published in any peer-reviewed study and there is no indication that Biochar Fund had ever intended to submit them to peer-review. Only 31 of the 75 trial plots yielded complete results and no statistical analysis of data was ever published.

It is hard to avoid the conclusion that the purpose of the project has always been to leverage future funds, including carbon offsets for biochar. Yet it is difficult to imagine that Biochar Fund, who, after all, have close links with the International Biochar Initiative (the main lobby group for biochar carbon offsets and other funding), could have genuinely believed what they told the farmers about likely imminent carbon finance. The IBI has been working for years – so far unsuccessfully – to get biochar recognised by any voluntary carbon offset certifiers or included into any trading mechanisms. And as investigations into a different soil carbon offset project by the World Bank, in Western Kenya, show, the transaction costs of such schemes are so massive that farmers will end up with virtually none of any such funds.

Yet while the farmers involved in the Cameroon biochar fund gained nothing from the project, it appears that Laurens Rademakers has done rather well from it. Not only did it help him raise the grant for the DR Congo project, but it also helped him leverage a second slightly larger CBFF grant for an unrelated project in Cameron, São Tome  and Equatorial Guinea. According to his personal website, he has created 13 different NGOs, eight of them in Africa, since 2006 and managed to obtain a total of $1.325 million in funds for different projects since 2009, most of it from ‘public calls’.


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  1. From what I read from the biochar initiatives they don’t claim that on all soils and under all circumstences charcoal burried in the ground has only postivie effects. Nevertheless first field results seem promising:

    “We did this trial with 75 farmers’ groups, representing around 1500 subsistence farmers. We found that biochar applied at a rate of 10 tons per hectare is as efficient as both organic and inorganic fertilizers. It increased crop yields on average by 240% on poor soils. Similar results were found for applications at a rate of 20 tons per hectare. This research is ongoing, because we want to investigate so-called residual effects…” (L. Rademaker)

    It was never claimed that yield in average increased by 240 %. I don’t know what the motivation for the wrong citation is? But it leaves a rather dull impression in terms of A. Ernsting’s honesty.

    Read more:

  2. @Cleibing

    I would have thought that almost anything of organic origin applied at a rate of 10 tons per hectare would have some kind of positive effect on plant growth – especially on very infertile old Congo Basin lateritic soils.

    But the point surely is how good is this for climate change? How much of that carbon actually stays in the soil? How much CO2 is produced in generating that 10 tons of ‘biochar’? If the conversion rate from biomass is only 10% as is claimed elsewhere in the article, then that means that probably significantly more carbon is escaping in to the atmosphere than could even *in theory* be captured in the soil.

    And how likely do we think it is that African subsistence farmers are going to be willing or able to turn dozens of tons of biomass into ‘biochar’ in order to be able to add this 10 tons of carbon per hectare to the soil? Do you have any idea of how much hard work that is?

  3. @cleibing (#1) – Thanks for this, but I’m really struggling to work out what your point is.

    Rademakers: “It [i.e. biochar project] increased crop yields on average by 240% on poor soils.”

    Ernsting: The project “has increased crop yields on average by 240%.”

    Jeremy Hance (who interviewed Rademakers on “In Cameroon, the Biochar Fund saw crop yields jump on average by 240 percent.”

    Ernsting provided a link to the interview on in the post above, so that you can read the interview (the same link that you provided in your comment). She seems to me to have honestly reported what Rademakers said. You seem to have read something else into what Rademakers said, but I’m afraid I haven’t the foggiest idea what that might be.

  4. @Chris Lang (3)

    To improve 240% yield on poor soils and improve 240 % yield on average is not the same thing, I would think.

  5. This looks to me like just more Europeans running around telling African farmers what to do – because European farming has been such an enormous environmental success!

    How much CO2 is produced for every calorie of European food actually eaten? Compared to how much for every calorie produced and eaten in Africa? How long can European agriculture been sustained? How long have African farmers been practicing rotational slash-and-burn farming?

    It’s the same old story in a different guise: cannot fix the problems there in super-rich over-consuming Europe, so go and tell poor people in Africa how to work even harder in order to clean up their mess for them!

    I think we need some Africans to go to Europe to tell the farmers how to stop pouring billions of tons of oil-based fertilisers and pesticides onto crops to produce inefficient over-processed meat, a third of which gets thrown away!

    ‘Biochar’? ‘Neo-colonial char’, more likely.

  6. I have been following the various carbon credit fiasco’s for some time now, is there such a thing as LEGITIMATE CARBON CREDIT or a LEGITIMATE COMPANY THAT CAN CERTIFY CARBON CREDITS from what i have seen there is not yet a scientific basis for measuring carbon in soils,under bush, canopy’s etc that is commercially viable and accurate.. I am getting the strong feeling carbon credits are the biggest con ever perpetuated on mankind and has led to massive fraud.

  7. In rebuttal may I offer Dr. Molina’s Nobel work. How the ozone hole story has been the most powerful success story of science saving the world from ecological disaster, now his current PNAS report will now do the same concerning carbon.
    Dr. Mario Molina, PNAS Report on Reducing abrupt climate change;

    Recent NATURE STUDY;
    Sustainable Biochar to Mitigate Global Climate Change

    Secretary Clinton Makes a big Announcement with The Global Stove Initiative;

    State Dept. Release;
    100 million clean-burning stoves in kitchens around the world.

    Biochar Work in Nine Developing Countries:

    World Bank Study: The survey data from 150 biochar projects located in 38 developing countries is available now on the IBI website at:

    The IBI now has 33 biochar affiliates around the world — including in China, India, Japan UK, US, Australia, Korea, Canada, Italy and Israel.
    Note also that our Japanese colleagues in the Japan Biochar Association have a very long tradition of biochar use and have been developing “modern methods” over the last thirty years. A governmental act officially acknowledged charcoal as a “soil ameliorator” back in 1988 and have completed work using Biochar as an in situ sorbent of Cd, and starting work on heavy metal radio-isotopes.

    PRO-NATURA INTERNATIONAL has the largest numbers of agroforestry soil-C & Biochar projects. Certainly the largest NGO, across the global south. They are very sensitive in both design and co-opting local social values for creating self perpetuated systems. Like the Exponential growth of biologic systems.

  8. On the surface this seems like a highly dubious venture in terms of producing veritable carbon credits. Monitoring soil carbon stocks in general is very expensive and time intensive, and that’s when you have a relatively even distribution of carbon. Now you are talking about monitoring a plot which is a literal mine-field of carbon pockets resulting from burying chunks of bio-char. And we haven;t even begun talking about the work needed for a full lifecycle analysis needed to measure the emissions in the production of biochar (not only from the wood needed to produce it, but also from the burnt crop residue). And on top of all that you have the inevitable avoided deforestation credits they will claim, which requires another set of complex and costly MRV requirements. Logistically, even if it does reduce emissions, the MRV and transaction costs would be far too high for this to be viable.

    And whoever decided on the backdrop to begin the carbon credit discussion at 4:00 in the video has a good sense of humor.

  9. @cleibing (#4) – I wonder why Rademakers did not bother to correct what Hance wrote in the introduction to the interview: “In Cameroon, the Biochar Fund saw crop yields jump on average by 240 percent.” Perhaps all the soils are poor soils.

    In his October 2009 post about the trials, Chris Goodall writes, “Some areas showed yield improvements of more than 250% over the control plots.”

    Unfortunately, the Biochar Fund website no longer exists, and the trial data seems to have disappeared with it. If anyone has a copy of the Biochar Fund’s trials in Cameroon, please send it to reddmonitor [AT] gmail [DOT] com. Thanks!

  10. @Erich J. Knight (#7) – Thanks for these links. Unfortunately, the links do not provide a rebuttal of the specific points raised in the article about two specific biochar projects, one in Cameroon and one in DR Congo.

    Let’s take them one at a time:

    The first paper, by Molina et al was published in 2009. It does not provide evidence of biochar reducing greenhouse gas emissions, it just suggests that biochar is one possibility. Here’s a typical statement from the paper: “The International Biochar Initiative estimates that biochar production has the potential to provide 1 Gt carbon per year in climate mitigation by 2040″ (my emphasis). Presumably I don’t need to point out that the International Biochar Initiative is hardly neutral.

    One of the main sources used by Molina et al is Sohi et al, which was also written in 2009. The title of that report is “Biochar’s roles in soil and climate change: A review of research needs”. Molina et al write that Sohi et al “note that the published evidence is largely from small-scale studies and cannot be generalized to all locations and types of biochar”.

    The “recent” Nature study was published in August 2010. It is also not based on trials of actual biochar projects: “The main aim of this study is to provide an estimate of the theoretical upper limit, under current conditions, to the climate-change mitigation potential of biochar when implemented in a sustainable manner.”

    Hilary Clinton’s announcement is about clean cookstoves (not biochar).

    Of the nine country projects that the International Biochar Initiative lists on its website, only one has a link to trial results. And that’s the Biochar Fund project in Cameroon and the link no longer works.

    The “World Bank Study” link is to a powerpoint presentation by Kelpie Wilson, International Biochar Initiative Project Development Director. It’s a survey of biochar projects worldwide, only 39 (about one-quarter) of which have “first measurable results”.

    And Pro-Natura is an NGO implementing biochar projects. So what? BP is an oil company that claims to be green.

  11. @Ralph (8) All points granted. Transaction cost are likely to be very high and precise estimation of carbon stocks and sequestration rates are difficult and lack a relliable methodology. But the ‘Biochar’ projects don’t primarily aim to generate carbon credits to be sold on the voluntary or compliance carbon market. It would only be a bonus if at some point of time it would be feasible to generate these credits. The positive direct effect strived for is increasing agriculutral yield on poor soils by charing residues that would have been burnt or left for decay otherwise.

    @Chris Lang (9) As I see it, Rademakers sets it right in his answer. He says cleary that it increased yield by x% (only) on poor soils.

    To design and set up trials that include 75 farmer groups will very likely include quite a range of soil conditions. To set up trials only on poor soils would be rather stupid since you lose the opportunity to study the impact of ‘biochar’ on different soil qualities.

  12. Almuth Ernstinga

    Re cleibing’s comments: My assumption from Rademaker’s quote was that he was referring to the average results in the Cameroon trials, because those soils are ones where constant efforts are needed to maintain soil fertility. Having said that, I’ve now gone back to the original page about the results on the Biochar Fund website and from that, it simply isn’t clear what the 240% relate to. There it says: “When char alone is added to the soil, at either the equivalent of 10 or 20 tonnes per hectare, grain yields are almost doubled (C10=+85%; C20=+89%).” The only place where the 240% figure turns up is this: “Extreme results on the C10 sub-plots: +211% (Mekora ), +240% (Tecla ), +300% (Bih ), +360% (Bate – to be uploaded) and +400% (Kofapru ).”. I.e. an ‘extreme result’, not an average.

    Re Erich Knight’s comments: Chris Lang has answered those quite comprehensively. Just to add a one extra comment, re the recent Nature study: That’s one that appeared in Nature Communications it is indeed very interesting. It calculates the biochar ‘mitigation potential’ based on various assumptions, which have been put into question by field study results and also by a recent soil science review published in Nature (to which the Chair of the International Biochar Initiative contributed) – see here about it: . What’s interesting about it is that the authors didn’t spell out in the article how much land they presumed would need to be converted to biochar production in order to achieve what they described as the ‘sustainable biochar potential’. One of the co-authors gave us the answer – they presumed it was 556 million hectares! That’s on top of the assumption that a large proportion of the world’s manure and ‘forestry residues’ would be charred.

  13. Please review my USBI 2016 Presentation;
    The full paper & citations, (no slides) is poste on my LinkedIn page;

    “The Civilization of Soil”,
    Historic hall marks of Green House Gas, (GHG), emissions are reviewed, providing repeated demonstration of anthropological land use changes on climate forcing.
    New Astrophysical and Paleoclimate concordance with extinction events demonstrating climate adaptation by prehistoric man.
    The Strata graphic measure of distinctions to the start, and effective end, of the Anthropocene.

    A review of new research concerning Soil Carbon, Carboniferous Aerosols and the synergistic ecological services supporting Net Primary Production, (NPP).
    The extent of Pyrolitic-Carbon’s fraction in soil and the first survey of the extensive deep soil carbon sink.

    Review of land use studies on Holistic Grazing, ungulate nutrient & carbon dispersal & climate control. Implications for Carbon Dioxide Removal, (CDR), when all Best Management Practices, (BMPs), are observed.

    How thermal conversion technologies can integrate and optimize the recycling of valuable nutrients while providing energy and building soil carbon.
    New discoveries from the Advanced Spectroscopy & Meta-Genomics studies in soil microbiology which demonstrate unaccounted for ecological services provided by a healthy soil. All extremely supportive to Argo-Ecological principles, Carbon & Regenerative Farming initiatives & Soil Carbon Standards and GHG protocols.

    Part and parcel to a healthy, high carbon and highly aggregated soil structure.
    Integration of Agricultural bio-energy production with nutrient and carbon cycles, enhancing ecological services.

    Exploring implications for human and animal health, extrapolating implementation at scale of bio-energy systems that conserve carbon for home health, energy and climate.

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