Two short articles well worth the read for terra preta enthusiasts:
Carbon project raises hopes: Waikato Times, NZ:
...Structural biologist Alfred Harris, process engineer Wolfgang Weinzetll and two Tauranga entrepreneurs are involved in Ecotechnology Ltd, which is working to reduce fertiliser use without hampering plant growth. The company is investigating producing a charcoal product from forestry and other organic waste which collects unwanted nutrients...
Recent work by Australian researchers showed wheat gained an additional $A96 per hectare in value when charcoal was banded in the soil with mineral fertilisers.
Is banded C the killerapp for agrichar? I don't know what the charcoal application rate was, but last I knew, banding equipment had limited material application capacity, charcoal is low density, and there was mineral fertilizer in the hopper also. A charcoal application rate in the neighborhood of about 100 lbs per acre seems reasonable to expect. At $100/ton for charcoal, material cost would be $5/acre ($A15/hectare). Is the value in comparison to a no-C comparison? I would surely like to see the research.
Seeder image source: Flickr by IRRI Images
Another May 15 article
Special Report: Inspired by Ancient Amazonians, a Plan to Convert Trash into Environmental Treasure (by Scientific American) has a great soil point-counterpoint under the heading: But is it viable? :
As with all new technologies, many questions about the ultimate utility of agrichar have yet to be answered. "As of now agrichar is not a uniform product," explains John Kimble, a retired USDA soil scientist. "And there's no easy way for farmers to apply it with existing equipment. They also need to know there is a large enough source of the material. Farmers are driven by profit, as is everyone, and they need to be shown that it will improve their bottom line."There are strong indications that soils amended with high (multiple tons/acre) rates of biochar need considerable time to reach their optimum. For setting where return on investment cycles need to be short, lower rates sustained for long periods of time may make more sense as a strategy for building soil C.
Complicating debates about the costs of agrichar is the paucity of data on the subject. "No one is sure what types of biomass should be used as raw material," Kimble notes, "or exactly what production methods work best, so calculating the costs is really an exercise in speculation."
In addition, scientists are finding it hard to replicate the original terra preta soils. "The secret of the terra preta is not only applying charcoal and chicken manure—there must be something else," says Bruno Glaser, a soil scientist at Bayreuth University in Germany. Field trials in Amazonia using charcoal with compost or chicken manure find that crop yields decline after the third or fourth harvest. "If you use terra preta you have sustaining yields more or less constantly year after year," he says.
"I'm skeptical about adding just a pure carbon source," says Stanley Buol, a professor emeritus from the Department of Soil Science at North Carolina State University's College of Agriculture and Life Sciences who spent 35 years studying Amazonian soils. "It will be black and look good," but will it contain enough inorganic ions, such as phosphorus and nitrogen, essential to plant growth?"
Many of the interactions between the char, the soil and the microorganisms that develop with time and lend the soil its richness and stability are still poorly understood. Glaser believes that the key to making agrichar behave like terra preta lies in the biological behavior of the original Amazonian dark earths—a difference he attributes to their age. "You would need 50 or 100 years to get a similar combination between the stable charcoal and the ingredients," he cautions.
"I think [research into the biological behavior of terra preta] is where the new frontier will be," Lehmann counters. If he is right, and scientists can perfect a modern-day recipe for agrichar, then its fans will not need Richard Branson's $25 million to jump-start their initiative—the annual demand for fertilizers exceeds 150 million tons worldwide.