Is biochar a part of the climate change solution?


Sunday, January 02, 2011    

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THIS is a turbulent time in which a confluence of events has created concern for the very survival of the planet in terms of human habitation as well as other life forms.

This concern may or may not be well-founded and there are deniers — some of an ideological bent, supported or by special interests, which would explain this bias; others with legitimate qualifications who genuinely believe the alarm is not justified.

Nevertheless, in the wider scheme of things, it seems justifiable to err on the side of caution and, should the concern be real, then one should act on the adage that a crisis is a terrible thing to waste.

Broadly speaking, concern for the physical world centres on climate change, energy, and food security. There is a close interlink between the three.

Climate change, inter alia, may, in a few cases, cause favourable agronomic conditions. In the majority of situations, the prediction is that of serious/catastrophic consequences. The current stated key process of climate change is that of carbon dioxide increase in the atmosphere, leading to the excessive trapping of the heat of the sun's rays.

Other gases may also be involved, but are not discussed here. Various computer modelling unequivocally predict that the subsequent warming may cause severely adverse conditions in many/most regions, as indeed is being demonstrated already in all the continents.

It is with this situation in mind that various schemes have been proposed to lessen the carbon dioxide burden in the atmosphere, some quite far-fetched and of uncertain unintended consequences, others apparently doable in principle, but very costly.

In recent years, there has been brought to fairly wide attention the "terra preta" phenomenon. The term is Portuguese for black earth/dark soil, areas of dark soil scattered over the Amazon region of Brazil, areas of otherwise light-coloured and very poor soil, unsuitable for repeated cycles of cultivation by humans, despite the lush forest cover.

It had been a puzzle that the earliest European explorers described the existence of extensive settlements of advanced nature, mainly along the watercourses, but that subsequent explorers had not seen indications of their existence.

This discrepancy remained a puzzle until an explanation was offered, that the then Europeans brought diseases new and fatal to the natives; also, that later the availability of metal axes and cutting tools enabled the easy cutting down of forests for slash-and-burn cultivation -- thus causing the further impoverishment of the Amazon soil.

The existence of the many "islands" of dark soil began to attract curiosity and scientific investigation. It was found that pottery shards and other indications of extensive human habitation were always present in those areas of dark soil. Such soil has been cultivated for many centuries, apparently self-replenishing, and maintaining high fertility to this day. It is much sought after and harvested for sale to growers.

Scientific investigation has shown dark soil to have a high concentration of charcoal-like carbon matter, hence the coloration. It is surmised that the natives had produced the charcoal-like material through pyrolysis -- the heating of woody material largely in the absence of oxygen/air. The natives may have purposely made and used the char for making the otherwise unproductive soil fertile.

With exposure due to media attention, this carbonaceous matter, in its modern incarnation as biochar, is riding a groundswell of interest as a carbon sequestering strategy and was suggested as one of the carbon mitigation steps in combating climate change at the UN-supported conference on climate change in Poznan, Poland two years ago.

What are the beneficial attributes of biochar, as incorporated in soil? Detailed examination of terra preta suggests that pyrolysis by the Amazon natives had been done at relatively low temperature, perhaps 350 C, instead of about 500 C for charcoal nowadays. This would have resulted in the retention of presumably beneficial volatiles which would normally be lost in the high temperature process. It is also undergoing a parallel and comparable interest as a soil ameliorant.

The physical attributes of biochar are stated to be:

* highly porous structure, giving rise to a very high surface area and with high adsorptive/absorptive property, with the consequent ability to retain nutrients, water, and support growth of beneficial microorganisms;

* soil texture amelioration property to improve plant establishment and nutrient availability; and

* permitting the presence of carbon matter in the soil as indication of soil fertility, with a lifetime of hundreds, maybe even thousands of years, in contrast to the short lifetime and hence low concentration typical of tropical soils.

Agricultural properties

The practical consequence of such properties, as reported by many accounts, is an almost "miraculous" ability to promote plant growth, in comparison with unamended soils as control, and also when, as control, conventionally fertilised soils were used.

Growth improvement, of course, is dependent on original soil quality, it being minimal where the soil is ideal in all respects, and very marked when it is poor.

Carbon sequestration

Perhaps as important as the agricultural implications, is the promise of biochar for climate change mitigation. For each cycle of pyrolysis and at least partial use of the resultant char for soil amendment, part of the carbon that was a major portion of the ligneous material becomes sequestered for an indefinite period. It would take many cycles, on a vast scale, to effect significantly reduced levels of atmospheric carbon dioxide. But no schemes considered are free of this scale constraint.

Biochar has been receiving serious attention by two major bodies -- the UN and the US Government -- and many private individuals and entities. For the US Government, the new administration has adopted biochar for an important role in its policy on climate change; it is key element in a number of individual bills by members of Congress regarding climate change.

Among the more developed countries, Australia and New Zealand seem to have been among the pioneers in sizable investigation and application. Other countries have now begun to be involved in the biochar movement and a number of initiatives have been established to promote the concept. Those countries are, as of now, relatively few in number, but general awareness is growing. Jamaica may not yet be one of that group, but six Caribbean islands are in the top 40 climate change hotspots, with Jamaica being 34th in a list of 140 countries.

Only Belize, it seems, of the English-speaking Caribbean countries, is presently participating in biochar studies. It should behove us to have a local investigation into the topic for the reasons already stated, and also for the implications for the local agricultural situation, which benefits that biochar potentially offers. Should the premise of climate change be accepted (in the direction of global warming), the consequences for the Caribbean are stated as follows:

* flooding of the lowlands, with devastating economic and habitation consequences for the countries;

* greater frequency and intensity of hurricanes and storms.

* 20-25 per cent reduction in rainfall; and

* agriculture — never very highly productive — will be even more stressed.

With the forecast that the equivalent of two Chinas may be added to the world population by 2050, food security has been taken very seriously.

List of activities

It is suggested that we be involved in biochar activity in the following ways:

* a survey of various methods of biochar production and to select and develop/adapt/adopt/a few best suited to local; capabilities and needs;

* the production of sufficient biochar to support the many experiments relevant to local agriculture;

* preliminary survey to determine, within reasonable limits of accuracy, the amount of ligneous/cellulosic material available for biochar production -- purpose grown ( not involving land now used for food crops), agricultural wastes, paper, packaging cardboard, wooden pallets, trees pruning, tree and plant detritus obtained after hurricane and storm passages; and

* a determination of a priority list of crops that could benefit from the use of biochar, and with special reference to the yield productivity of important export crops, for example, ginger (now effectively dead as an export commodity).

Added-value research to realise the huge economic potential of grossly neglected crops such as turmeric, cerasse, peppermint, sarsaparilla, etc, is also recommended. In addition, there should be research on possible enhancement of "restored" bauxite land productivity and collaboration with individuals and entities to effect expeditious and maximal results from various areas of investigation.

There should also be increased public, governmental, agricultural and educational awareness and engagement while establishing Jamaica as a co-ordinating centre for regional biochar research and application.

A position paper on biochar should be formulated by the Government and other bodies, and which can then be a part of the contribution of Jamaica and sister islands (plus Belize and Guyana) to the annual international climate talks.

Other suitable activities as may suggest themselves during the course of the programme.

Expected results

* Agricultural yield potential equal to, or greater than conventional fertilisation practice, less foreign exchange requirement for inorganic fertiliser.

* Continuous improvement in the physical, chemical and biological properties of treated soils.

* Better produce quality in nutrition, appearance and shelf life.

* Earlier crop maturity -- less resource input, labour cost, water consumption.

* Eco-friendly -- less fertiliser run-off, lessened groundwater and marine pollution, reef/coral protection, lessened nitrous emission (also a very potent greenhouse gas) emission, as well of course, lessened carbon dioxide concentration.

* Potential of a significant industry in biochar production, and of a more efficient conventional charcoal production for domestic heating .

* Enhancement of school and home garden projects.

* Significant economic potential in carbon cap trading.

* Lessened problem of ligneous/cellulosic waste disposal

* Substantial value-added agro-industry arising from availability of commercially important crops produced at reasonable costs; as well as the means of drying important crops -- coffee, pimento, turmeric, ginger, cocoa, copra -- through heat produced by burning pyrolysis gases or using some of the biochar produced.

This avoids the traditional, unhygienic and indeed primitive method of drying on "barbeque" surfaces, and the low-throughput, sunshine-dependent solar drying.

— Dr David Lee holds a PhD in organic chemistry and has worked with the Scientific Research Council.





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