| Some of you will probably not consider this a "hot" topic. I do though. In the face of a likely expansion of the tropical zone, it's a hot topic that could prove a saving factor for humanity. I know at least one debator here is aware of this subject - that wouldn't necesarily be the case at the gardening forums.
I've been adding ash to my soil for years - ash with quite a bit of charcoal in it. I havn't noticed persistence of the charcoal, particularily. I wonder if the bio-char and 'terra-preta' phenomenon cannot happen where the ground freezes regularily?
Bio-char
Soil Biogeochemistry
Johannes Lehmann
Basic Concepts
Projects
Work by others
Pictures
References
Bio-char: the new frontier
Inspired by the fascinating properties of Terra Preta de Indio, bio-char is a soil amendment that has the potential to revolutionize concepts of soil management. While "discovered" may not be the right word, as bio-char (also called charcoal or biomass-derived black carbon) has been used in traditional agricultural practices as well as in modern horticulture, never before has evidence been accumulating that demonstrates so convincingly that bio-char has very specific and unique properties that make it stand out among the opportunities for sustainable soil management.
The benefits of bio-char rest on two pillars:
1- The extremely high affinity of nutrients to bio-char
2- The extremely high persistence of bio-char
These two properties (which are truly extraordinary - see details below) can be used effectively to address some of the most urgent environmental problems of our time:
1- Soil degradation and food insecurity
2- Water pollution from agro-chemicals
3- Climate change
"Soils with bio-char additions are typically more fertile, produce more and better crops for a longer period of time."
THE TWO PILLARS OF BIO-CHAR PROPERTIES
Nutrient Affinity
All organic matter added to soil significantly improves various soil functions, not the least the retention of several nutrients that are essential to plant growth. What is special about bio-char is that it is much more effective in retaining most nutrients and keeping them available to plants than other organic matter for example common leaf litter, compost or manures. Interestingly, this is also true for phosphorus which is not at all retained by 'normal' soil organic matter.
Reading:
Sombroek, W., Nachtergaele, F.O. and Hebel, A.: 1993, ‘Amounts, dynamics and sequestering of carbon in tropical and subtropical soils', Ambio 22, 417-426.
Mikan, C.J. and Abrams, M.D.: 1995, 'Altered forest composition and soil properties of historic charcoal hearths in southeastern Pennsylvania', Canadian Journal of Forestry Research 25, 687-696.
Lehmann, J., da Silva Jr., J.P., Steiner, C., Nehls, T., Zech, W. and Glaser, B.: 2003a, ‘Nutrient availability and leaching in an archaeological Anthrosol and a Ferralsol of the Central Amazon basin: fertilizer, manure and charcoal amendments', Plant and Soil 249 , 343-357.
Lehmann, J., Kern, D.C., German, L.A., McCann, J., Martins, G.C. and Moreira, A.: 2003b, ‘Soil Fertility and Production Potential', in J. Lehmann, D.C. Kern, B. Glaser and W.I. Woods (eds.), Amazonian Dark Earths: Origin, Properties, Management , Dordrecht, Kluwer Academic Publishers, pp. 105-124.
Liang, B. , Lehmann, J., Solomon, D., Kinyangi, J., Grossman, J., O'Neill, B., Skjemstad, J.O., Thies, J., Luizão, F.J., Petersen, J. and Neves, E.G.: 2006, 'Black carbon increases cation exchange capacity in soils', Soil Science Society of America Journal, in press.
Persistence
It is undisputed that bio-char is much more persistent in soil than any other form of organic matter that is commonly applied to soil. Therefore, all associated benefits with respect to nutrient retention and soil fertility are longer lasting than with alternative management. The long persistence of bio-char in soil also make it a prime candidate for the mitigation of climate change as a potential sink for atmospheric carbon dioxide. The success of effective reduction of greenhouse gases depends on the associated net emission reductions through bio-char sequestration. However, a net emission reduction can only be achieved in conjunction with sustainable management of biomass production. During the conversion of biomass to bio-char 50% of the original carbon is retained in the bio-char, which offers a significant opportunity for creating such a carbon sink.
Reading:
Pessenda, L.C.R., Gouveia, S.E.M. and Aravena, R.: 2001, ‘Radiocarbon dating of total soil organic matter and humin fraction and its comparison with 14 C ages of fossil charcoal', Radiocarbon 43 , 595-601.
Seifritz, W.: 1993, ‘Should we store carbon in charcoal?', International Journal of Hydrogen Energy 18 , 405-407.
Schmidt, M.W.I. and Noack, A.G.: 2000, ‘Black carbon in soils and sediments: analysis, distribution, implications, and current challenges', Global Biogeochemical Cycles 14 , 777-794.
Shindo, H.: 1991, ‘Elementary composition, humus composition, and decomposition in soil of charred grassland plants', Soil Science and Plant Nutrition 37 , 651-657.
MEETING ENVIRONMENTAL CHALLENGES
-(in preparation)-
LAND-USE SYSTEMS AND BIO-CHAR USE
Bio-fuel production through low-temperature pyrolysis
"Combining bio-energy production with bio-char application to soil offers one of the most exciting perspectives of future land-based production technologies."
(read more about Bio-char and Bio-energy)
Reading:
Okimori, Y., Ogawa, M. and Takahashi, F.: 2003, ‘Potential of CO2 emission reductions by carbonizing biomass waste from industrial tree plantation in south Sumatra , Indonesia ', Mitigation and Adaptation Straegies for Global Change 8 , 261-280.
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