Thanks for the response Ron. I am happy to see that we are in agreement about many or most points.
My characterization of the motives of biochar researchers is poorly informed, so I accept your statement that C sequestration is first priority for workers in your camp. But it still seems to me that most articles promoting biochar have spent more time developing the soil quality and fertility benefits than on the C sequestration benefits, which are good points in favor of biochar, but do not suggest a focus on sequestration. When you say that crop residues will be transported from highly productive lands to less productive lands in developing countries are you referring to intercontinental transport, from temperate regions to tropical? If not, are there sufficient highly productive agricultural lands in developing countries to supply biochar to the poorer soils? (developing countries is not a good description of what I mean; which is countries whose agriculture is dominated by poor, low yield soils, primarily tropical, high temperature soils, e.g., oxisols, aka ferralsols). >From what you say about the need for about half of the biochar for high >temperature soils to come from forest lands, I think that you agree that >harvesting woody materials from local forests in the tropics is a very >important source of biomass for this application of biochar sequestration >technology on a large scale. This is why I emphasized management in >discussing responsible biochar implementation in tropical systems. Without >cautious management the large-scale conversion of these forests to >anthropogenic use would have significant potential of ecological harm. Am I >wrong? A quibble: Me thinks a 50% increase in agricultural yields _is_ a “much higher” increase. You imply that some researchers are applying biochar with no-till. References please. Finally, I goofed in stating a saturation level for biochar of 50 kg/ha. Mea culpa, I meant 50 Mg biochar C/ha (only off by 1000x!). My reference for this rate is Chan et al., Australian Jour. Soil Research 2007, 45:629. I should have checked before pressing send. So my point is that biomass harvested from maize cultivation, used to produce biochar (10Mg aboveground CR produced /ha, If biochar can be added to soil without tilling, and the higher CR removal rates (i.e., 60%) implemented any soil receiving biochar, then saturation at 50 t biochar C/ha could be achieved in about 25 yr, after which 60% of above ground crop residues could continue to be harvested and be used for other purposes, such as burial or energy production or export to the tropics, potentially without negatively impacting fertility in the modified temperate soil. = Stuart = Stuart E. Strand 490 Ben Hall IDR Bldg. Box 355014, Univ. Washington Seattle, WA 98195 voice 206-543-5350, fax 206-685-9996 skype: stuartestrand http://faculty.washington.edu/sstrand/ From: rongretlar...@comcast.net [mailto:rongretlar...@comcast.net] Sent: Monday, September 20, 2010 3:14 PM To: Stuart Strand Cc: geoengineering@googlegroups.com; marty hoffert; andrew lockley Subject: Re: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC Stuart etal: Thanks for your response and apologies for mine being tardy (and maybe too long-winded).. Yesterday I left Manaus, Brazil - and I am still playing catch-up. I have only read a few of the other messages in this thread, so hope this will cover the topic until tomorrow.. A few inserts below. Ron ----- Original Message ----- From: "Stuart Strand" <sstr...@u.washington.edu> To: rongretlar...@comcast.net, "andrew lockley" <andrew.lock...@gmail.com> Cc: geoengineering@googlegroups.com, "marty hoffert" <marty.hoff...@nyu.edu> Sent: Wednesday, September 15, 2010 9:05:01 PM Subject: RE: [clim] Re: [geo] Carbon sequestration workshop Sep 9-10, Heinz Center, Washington DC Ron and other biochar folks, My impression is that most of the biochar research is focused on use in the developing world where there is an emphasis on improving soil quality, particularly of low carbon soils. [RWL1: I wish there were more R&D in developing countries; it is certainly needed. But almost no funded research exists in any country. I would guess that the largest amounts are in Australia, the US, and the UK. The official USDA/ARS total is close to zero; all is being boot-legged. But there is enough of that to approximately equal the official amounts in the other two countries - which I believe doesn't yet get much over $10 million per year. Hope someone can correct this guesstimate.] Carbon sequestration is an important side effect, but the primary motivation is to improve soil quality and crop yields. [RWL2: I have to disagree. The main justification in my circles is sequestration - and certainly so when talking on these two lists (as did Peter Read). Biochar was in the UN dialogs leading up to Copenhagen mainly for climate reasons. The IBI web site makes no distinction between the climate, soils and energy $ streams. But I acknowledge there are strong differences between researcher motivations.] Since crop yields in these soils are low, biomass for biochar production must be obtained from non agricultural land, usually forest or brush. [RWL3: Disagree in part because of #2 answer. The dominant resource for Biochar is usually stated to be ag wastes/residues (by assumption from the most productive land).. My estimate is that an approximately equal amount can come from forest management (where the world has 3 times as much dedicated area). The word "brush" is not used in the Biochar documents I read - but if this equates to pasture land and mine reclamation, I can agree. But some trasnfer of carbon for Biochar from highly productive land to that which is barely producing, will probably occur. Many of the drivers discussed further below are in the form of reducing inputs (nitrogen, phosphorus, water, etc) by returning Biochar to the ag land from which it was derived. I reject the idea that farm land is to be excluded.] So biomass collection for biochar must be managed to prevent ecological harm, but eventually biochar treated agricultural soils will support much higher biomass production (including crop residues) than they can now. Have I got that generally correct? [RWL4: Yes. But the words "much higher" are open to argument. I mostly see 50% improvement as a global average - although the Terra Preta soils that 60 of us visited the last few days are reported to have double and triple productivity (and last had added carbon 500 years ago). This good time to repeat there is continuing benefits. Doing a one year (or even 10 year) economic analysis grossly underestimates the way a farmer will view this. I asked in Manaus about the difference in land values - and was told a factor of 5 or 6 has been noted. ] I don’t hear so much about biochar production and use in highly productive agricultural regions such as the American Midwest. Probably, because those soils are already highly productive. Am I right about that? [RWL5: Yes. But some of the roughly 200 Biochar papers presented in Rio last week emphasized water retention (avoidance of total crop failure last year in one Australian trial. The same researcher (Dr. Lukas van Zwieten) reported on a possible (he is very cautious) climate mitigation impact from reducing N2O release approximately equal to the CO2 benefits. A third item under discussion was the ability to generate char from waste streams that are normally only flared (or worse); tipping fees will occur in some cases - very unlikely for most other bio-sequestration options. A fourth topic in Rio was conserving and recycling phosphorous. These benefits are not limited to developing countries.] There is a problem with ideas for removing and using crop residues from productive ag regions, whether it is BECS, CROPS, burial, or cellulosic ethanol: the limitation on the supply of the crop residue. [RWL6: And Biochar does NOT suffer from this limitation, if a fraction is returned to the soil. This is especially attractive for sugar cane operations, as pne example, where the bagasse is not now treated efficiently - being so much of it. That changes with Biochar. At larger operations, BECS may still be applicable. Some of your listed alternatives also require a fossil energy supply; Biochar has plenty of energy to hybridize wind and solar systems - and allow much greater penetration - as input biomass can replace batteries and pumped hydro. I see no reason to think we can't get to 100% renewables via Biochar. ] Best recommendations from soil scientists is that only 30% of the CR can be removed on average from productive farmland without negatively impacting soil carbon levels (Wilhelm, et al. Agron. J. 2007, 99 (6), 1665; Johnson et al. Agron. J. 2006, 98 (3), 622). [RWL7: And Biochar adds carbon at a faster rate - with no evidence of plateauing. The terra preta soils today have up to 70 times as much soil carbon as the base soil. Most researchers are working with a no-till approach.] Erosion can be suppressed by leaving as little as 30% on the soil. (I should mention that there some soil scientists strongly oppose removal of any above ground biomass). [RWL8: Yes. agreed. Biochar can be profitable with that restriction. But in addition, causes of erosion are diminished as Biochar encourages appreciable increased microbe and fungi populations. With perennials, the root system can be much increased - and probably reverse the present world-wide soil erosion problem. I don't believe any of the other bio-sequestration options have that potential.] Biochar offers a way around this limitation: for the most productive crops (like maize), biochar levels could be brought up to levels shown to positively affect yield (50 kg/ha) in 30 years or so. [RWL9: I believe your 50 kg/ha improvement will prove to be conservative. This is equivalent to a total 30-year delta of 5 grams [of something] per square meter delta. I'd like to see a citation on this number (and what the units are - carbon, dry biomass, etc). Average global NPP (which I don't think is the right unit for predicting Biochar impact) is about 40 grams C/m2-yr (0.4 tons C/ha-yr coming from dividing 60 GtC/yr by 13 Gha). When we use char on degraded soils (where today's NPP is negligible), we could get up to today's global average NPP, so the 30-year delta could be 40 grams C/ha-yr - not 5. We haven't mentioned increased food supply, but that comes along almost for free. We hear of a Bolivian biochar test (ref Dr. Niklaus Foidl) where the average ears per stalk were more than 10. ] After that CR removal rates could be doubled to about 60% without negatively impacting soil carbon and used for other types of carbon sequestration. [RWL10: Yes, maybe. But with forest management and coppicing of perennials, the removal in any one year could be well above 30% of the annual growth, and the average increased yield also can be higher that 30%. If one pyrolyzes 60% of the annual carbon produced - and returns 30% (pyrolysis typically assuming 50% conversion efficiency) as a Biochar with lifetime measured in millennia, then there is long-term growth of soil carbon, not only stability. None of the other bio-sequestration options can make this claim. We may find that 100% removal of the annual growth (and 50% return) is feasible for a mature coppicing situation in which one is mainly trying to keep open the forest canopy. Some Biochar proponents are talking of continually taking out whole trees to maximize the total discounted value (with the lumber also being an additional sequestration mechanism - as REDD hopefully will encourage. The available data suggests that we can add a very large amount of char to soils in many/most cases with almost linear improvement in soil productivity in some cases. This is not to say we know how to do it every time at present - but we are beginning to realize how complicated the prediction is - and that taking care with the nitrogen cycle is very important.] Again apologies if this was confusing. I didn't have time to add citations, but there is a wonderful list of references at www.biochar-international.org - and I'd love to exchange further dialog on anything above. There is plenty of good R&D now appearing regularly - despite the paucity of funding. RWL] -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To post to this group, send email to geoengineer...@googlegroups.com. To unsubscribe from this group, send email to geoengineering+unsubscr...@googlegroups.com. For more options, visit this group at http://groups.google.com/group/geoengineering?hl=en.
