DEAR NEW FARM:
I read Paul Hepperly’s article on Pre-Columbian
charcoal soils while researching a lecture on urban soils
I will deliver this month in Singapore. Do you have any findings
on the amount of charcoal that should be added to the soil
or the particle size? I have found that Shell is marketing
charcoal in Malaysia for horticultural applications, and I
am attempting to find out their practices and recommendations.
Are you aware of anyone using charcoal in temperate soils?
My work is in urban soils. I often design soil systems that
are placed under sidewalks where there is no ability to add
fertilizer or compost after the completion of the construction.
Do you think that charcoal might have an application in this
situation? If so, at what rate might you want to add charcoal
to the soil?
Are you aware of any environmental impacts from charcoal
production? Is commercial charcoal produced from scrap and
Dr. Paul resonds:
My family name on my mother's side is Urban, so we are probably
Horticultural charcoal is used as de-toxicant especially
in sensitive orchid culture. For this purpose, only small
amounts are needed. Some pilot plants get hydrogen from biomass,
leaving char as an amendment. This would be the most benign
way of charging soil with char carbon (see the www.eprida.com
There is relatively little on the rates of charcoal that
would help as a soil amendment, but in studies on Indian Black
soils they were using it at about 10 percent by weight to
test its effects with good results.
Good luck with your talk,
us with comments, suggestions and questions.