I came across this recent interview on the net by Matthew Wright with Johannes Lehmann. He is the leading academic voice on the subject of terra preta soils. It presents the current state of work in the area. I continue to be convinced that the earthen kiln method replicated with today’s tools is the quickest way to enter the field trial format. Mechanized solutions have to evolve.
An important open question is to what extent the Amazon Indians used legumes with their corn – cassava culture. It seems likely in view of the corn – bean squash culture of the North Americans.
I would like to see squash properly reintroduced as a staple into our diets. I always knew that they cubed the flesh and dried it out for storage. I have since learned that they also smoked it. This would have real culinary potential which has been lacking.
Drawing down carbon - Johannes Lehmann of Cornell University talks Bio Char
Fri, 2008-03-07 07:23 — admin
We talk to Professor Johannes Lehmann about Bio Char
Matthew Wright: Following on from our interview last week with Adriana Downie from Best Energies, we've got doctor Johannes Lehmann, whose an associate professor of soil fertility management and soil bio-chemistry at New York's Cornell University. Prior to this he co-ordinated an interdisciplinary research project on nutrient and carbon management in the central Amazon for the Federal Research Institution of Forestry at the University of Bayreuth, Germany.
His work experience includes applied and basic research in Sudan, Togo, Tanzania, Kenya, Malawi, Brazil, Columbia and Ecuador. Professor Lehmann's publications range from dry land research of nutrient recycling irrigation systems to the rehabilitation of highly weathered soils in the humid tropics. From research on phosphorous dynamics in heavily manured soils to basic principles of carbon recycling in soils.
Most recently he's been talking about terra-preta, agrichar, the ability to draw down atmospheric carbon. We'll see if we've got Dr. Lehmann there.
Johannes Lehmann: Good morning, and for us its good afternoon actually.
MW: Yes, good afternoon, because its late afternoon in NY and we've got you on the line from there. Thank you for joining us. Tell us a bit about yourself.
JL: Like you said, I'm a faculty member here at Cornell Uni. I'm in a dept called Crop and Soil Sciences. So, I'm a soil scientist, a soil bio-geochemist.
I'm very interested in understanding how soils work and especially how nutrient cycle, how carbon is sequestered in soil. When I was working 10 yrs ago in the central Amazon, I lived in Manaus in the central Amazon for three yrs working on degraded Amazonian soils. I couldn't help but stumble on these so-called terra-preta soils, black earth as it was in Portuguese. These black soils are scattered all over the Amazon and are very rich in humus and carbon and very fertile, and that's where all this started.
MW: So tell us a bit more about those black soils, how they came about, their longevity, and things like that.
JL: That's really quite a fascinating story. Also, the discovery of these soils, we have the earliest scientific descriptions come from about the 1860's. At that point it was absolutely unclear how these soils originated and where they came from.
There were wild theories until the 1980's that speculated whether these were soils from volcanic fallout or some old lakes that dried out; but as it turned out in the 90's only, that these soils were inhabited by indigenous populations before the arrival of the Europeans, which around 1500. The first person to travel down the central Amazon was Francisco de Orellana. He reported back to the Spanish court that there was a thriving population in the central Amazon. Productive landscapes, intensive agriculture, very large, sophisticated civilisations. Well, the Spanish came back 50 years later and the found nothing.
Then nothing was done about that. One thought that Francisco de Orellana was a liar and a cheater that just made up stories to impress the Spanish court. But now it turns out that we find these remnants of these civilisations and they provide us important clues. In turn, they taught us very important lessons that we now build a new strategy to sequester carbon and mitigate climate change on. And that's built on these soils that are clearly originating from these populations that lived there from 500 years before present to the oldest ones reported are about 8000 years old.
So in this period the populations enriched the soil with organic matter and this is still the fertility and organic matter that we see today that originated from these indigenous populations up to 7000 years ago. And its still there, in an environment where there should not be a fertile soil, where there should not be a soil with high organic matter content, and its still there after such a long period of time.
MW: So that fantastic, and the actual process to get the terra-preta is a great way to extract the energy value from biomass and even, perhaps low-caloric value biomass. Is that the case?
JL: Yes, this is a fantastic opportunity to weave this knowledge, or this insight, from old soils into modern land use and bio-energy. But let me just step one second back, its also important to realise the properties of these so-called terra-preta are not just built on ?um, that there is more humus, more organic matter in these soils. It's a very specific type of organic matter that's in these soils. It is a charcoal-like substance, a very black substance. We know of charcoal from the B-B-Q. But this is charcoal soil, and this type of organic matter is not only very stable, but it does also what other organic matter does in much more efficient way. So, its not just hanging out there a much longer period of time, but it also does all the good things that humus and organic matter does in a much better way than manure or compost could do.
And that's where these intriguing properties really, I think, are driving the current effort. And as you said, there now in the contemporary land use there are extremely exciting opportunities to produce such charcoal-like substance, we call this substance these days actually biochar because it is produced for the purpose of soil amendment, not primarily to put on your B-B-Q.
That is, of course, very exciting for the bioenergy community, because that can be produced with a certain type, with a certain method, of producing energy by using biomass. And it seems you have talked with the companies that are engaging with these technologies. The technology is called pyrolysis. Its sort of cooking biomass in a pot with the lid on, and when you do that, when your water's gone when your spaghetti's? um, then you will have a black substance and not spaghetti anymore. And that's exactly biochar. In other speak, it would be a thermal degradation of biomass, and you end up with this black substance. A bioenergy concept exists that builds on this pyrolysis, and as a by-product, that is this biochar.
Until about four years, 5 years ago, the companies and research programs that concentrated on pyrolysis were primarily concerned with producing bioenergy, until these scientific communities that looked at terra-preta and the scientific and companies that looked at pyrolysis bioenergy found out that they have a great opportunity to work together. That you can actually produce bionenergy by this process called pyrolysis and still retain a significant amount, maybe in some cases more than half, of the biomass carbon as a biochar that you can then return to soil and simulate a very important factor, why these terra-preta soils in the Amazon are so fertile for such a long period of time.
MW: At Beyond Zero Emissions, we believe in taking our atmospheric carbons as close to near zero emissions as possible, and then trying to balance that. Of course, agrichar can be one way of doing that. Then we're talking about actually pulling down the carbon debt. That's the carbon that the West has emitted in its industrialisation, which is about 200 billion tonnes. Do you see enough land that's appropriate to sort of achieve that sort of pull-down in a short period, in 10, 20, 30 years sort of thing?
JL: Absolutely, and I can tell you why I think that, but what I explain now is of course a theoretical potential that's not fettered??? 11:19 against economic realities of competing strategies and political influences. Why I think it is possible, because you can do calculations and look at waste biomass in agriculture or forest thinnings, agricultural by-products, crop residues, etc. These taken together would be more than enough to put a significant dent into the rising co2 curve. Conversely, there are more than enough soils that would need boosted soil fertility and could very well need this biochar. It is entirely conceivable that this can play a major role.
Another factor is that this is a technology that already exists. It is not something where we speculate that we have the development of 5 or 10 years until we get to a stage where it's technologically feasible. This is technologically feasible right now. And it is not a very complicated technology. It is a very ancient technology in its basic function and charcoal making is one of the most ancient technologies that humanity invented. It's a very, very old technology. However, producing energy from that technology requires quite a bit more technology, but the mere process of converting biomass into biochar is a very ancient and basic technology and can be done in massive proportions within a very short period of time. I think it's a very important opportunity that we should have a very close look at.
Of course, there's a multitude of competing and old intelligent solutions, to our energy, as well as climate, problem. And I think that there are other bioenergy options that deserve a very close look and have definitely a place in a portfolio of options. But I can't see that there's another opportunity such as pyrolysis with a biochar return to soil that offers clear carbon-negative bioenergy where for every unit of energy that you produce you're actually net-sequestering carbon in the terrestrial ecosystem, or anywhere on Earth.
MW: Just to let listeners know, we're talking to Johannes Lehmann whose an expert in soil fertility and bio-geochemistry. You're with Radio 3CR and its 8:45AM.
Dr. Lehmann, we've talked about the pyrolysis machine and how we can actually cook up the biomass, which can be a biomass residual from cropping, or something like that, and then getting the synthetic gas which is carbon monoxide and hydrogen and turning that into a viable fuel, and then sequestering that residual char and with each new crop we can perhaps pull down 50% of the carbon, (by mass of that actual crop)?you're giving us a solution to those two things and also you talked about the fact that we could probably get marginal lands and restore those. So this is going a long way. We're taking marginal farm land and restoring that, we're drawing down atmospheric carbon to start getting rid of that carbon debt, and we're creating a fuel source. Can it do all these things?
JL: It can where its given the opportunity to. You have to realise that there are of course a lot of soils that are already good. A farmer in the American Midwest that already harvests 9 tonne of corn grain, or 8 tonne of corn grain, that farmer will certainly not double the yields of their crops. But they might be able to reduce the fertiliser amounts because biochar in soil is able to retain more of the fertiliser that is added to soil and thereby possibly reducing the costs of fertiliser additions and other unwanted offside effects such as groundwater pollution or eutrophication of surface waters. That is always a question of the site that you are working at and the objectives that you follow and the priorities.
I have talked with farmers who are right now producing biochar on their farms with large scale pyrolysis machines that are absolutely not interested in producing bioenergy. They're completely content in producing biochar from sustainable biomass production and putting that biochar in soils without even thinking of bioenergy at this point. There might be others who are interested in remediating soils in remote areas in mine??? soils where it also would be difficult to transport the energy anywhere else; it would cost more energy than the energy is worth begin with.
If the objective is to remediate soils and its worth your while doing that without harvesting the energy that is gained from this process, then that's fine too. You might in some cases opt for um, if energy prices are high, and at the moment you have a problem selling your biochar, you might produce only energy. The versatility is really great and you can decide which markets you want to tap.
MW: Given the finite resources, and the finite land mass to feed an ever growing population around the world, it's generally the case that you're going to get the heat by-product and you're going to have the char at the end, so I guess it would be best that all things are harvested from the process. Would you agree with that?
JH: Most definitely. Absolutely, but there's a limitation. If you have a remote area, if you're producing energy in a remote area, you have 2 choices. Either you're transporting the biomass which costs a lot of energy or you're producing the energy where the biomass is produced and then you have to transport the energy to some end user. The proximity of biomass production, energy production, and energy consumption is key for any bioenergy concept. There are clear thresholds from which distances this system would not work any more.
But that means it has great strength in distributed energy production, for farms, for small farms, I'm thinking for instance Africa where there you have a lot of energy use from biomass individually from households, and in small villages. If these households and these villages could be equipped with pyrolysis bioenergy rather than complete burning of their biomass, they could get the same amount of energy out of the biomass that their using, cook the same amount of food per day that they were cooking with their identical amount of biomass and still retain about half of their carbon to be returned to their ever degrading soils. This could mean a tremendous change that would be largely driven by the need to restore soil fertility but by the same token possibly make a significant contribution to mitigating climate change.
MW: And of course, that what we're here for at Beyond Zero. Dr. Lehmann, in terms of, before we touched on those high yield farms where there was possibly decreased requirement for fertilisers, and a lot of fertilisers are actually sourced from petroleum products which of course have embodied carbon in the process of exploration, extraction, distribution, cracking?do you see that that is the case, that we could mitigate the need for much of those petroleum-based fertilisers?
JL: Our hope is to demonstrate clearly that we can significantly reduce the need. Any plant needs nitrogen. For instance, nitrogen is the single most energy intensive, therefore carbon intensive fertiliser nutrient. Typically around 50% of the energy that goes into any given agricultural product that you buy off the shelf comes still from that energy used for the nitrogen fertiliser during production on land. So achieving a significant reduction in the use of that nitrogen fertiliser could have a significant effect on the energy consumption and carbon balance of an agricultural product. I would be perfectly content if we can reduce the nitrogen need of the cereal crop by 20 or 30%. That would be a huge achievement.
Of course we will never be able to completely reduce it unless we are working with legumes, and biological nitrogen fixation, which is entirely feasible as well. But in intensive role production in much of the world, unfortunately, most farmers still have to work, presumably, with mineral fertilisers. But I believe we will be able to demonstrate that these can be reduced.
Then there's always still a significant jump to make from demonstrating on a research farm, or even on farm research, that you can decrease and still get the same amount of yield and the adoption by farmers. So that will be a much more difficult sell to get farmers to decrease their fertiliser amounts from a yield safety perspective. But eventually, and with rising energy, and therefore rising fertiliser prices, I believe that there is enough economic reason and economic incentive to look for any opportunities to be able to reduce fertiliser additions.
MW: So the reduced requirements for nitrates and nitrogen, could that actually help with the introduction of bio-fertilisers; the fact that you don't need to go as far if you combine the two opportunities?
JL: That could very well be. That is really a far-reaching question, and whether we can actually achieve to combine the two and package an attractive management scenario. That would be the ultimate goal, and I can see that there is a lot of merit in researching that further.
MW: Also, now I understand that there are a lot of trials under way. How are they progressing? Can you give us an idea of what the early results are, and if there was a lot of help and assistance, how quickly could we get this stuff commercial?
JL: That is really the single greatest challenge; to scale it from laboratory investigations to significant farm-scale trials. And why this is a challenge? Because for doing that you need a significant amount of that biochar for doing field scale studies. And the catch 22 at this moment is that there are not enough companies around that produce a biochar with facilities of the scale that would be conceivably be installed in the future, in a biochar economy. Therefore the research is greatly hindered by the availability of commercial plants that work on this basis. And since these are quite significant power plants, this is also an undertaking that can't be just done by individual researchers in their programs. These are university wide, or program wide initiatives of a 'Department of Energy' scale that is beyond research scale. That is a huge drawback of the current situation. But the handful or so of trials that are under way, and a significant amount of these trials are actually situated in Australia, so far they all show very promising results but also some results where we clearly see that there is absolutely the need for optimisation to biochar products. Not all biochar products are efficient to the same extent, and there might be even be some biochar products that are detrimental to plant growth, similar to any fertiliser. You can apply too much of a fertiliser and kill your crop. You need to have the right dosage and the right composition of fertiliser. And the same applies to compost or manures, and of course the same applies to biochars.
The density of data, and the intensity of research, needs to be accelerated to a significant extent to fine tune and identify those biochar types that are the most effective for increasing crop yields. But that can be done by extension agencies, and on extension farms, with on-farm trials very quickly, within a couple of years. Again, the technology is there, we've just got to implement it.
MW: Great. Thank you, Dr. Lehmann. We've been speaking to Johannes Lehmann from Cornell University, who's an expert in soil fertility management and soil bio-geochemistry. It was a most interesting and intriguing discussion, and we'd love to have you back on the show in a few months if you'd be happy to do that.
JL: It was a pleasure.
MW: Fantastic. And I think our listeners will agree that we're all the wiser now. Just in one or two words, do you think we can start some initial, small-scale commercial stuff right away, or are we five years away.
JL: Absolutely, we should be starting this right away, and hopefully that will enable the farmers, that are ultimately the best researchers, to kick into gear and try this out and find out what works best for their soils and for their crops.
MW: Great. Thank you Dr. Lehmann. You're with the Beyond Zero show and just to wrap up we'll see you all tomorrow at the Sustainability Convergence which is at Northcote High School?