Terra Preta and Ants - Rooftop Experiments

Tom Miles

Terra Preta and Ants - Rooftop Experiments
Dr. Sai Bhaskar Reddy, India, December 13, 2007

Dear All,
After the successful field trials in Alkaline soils http://e-alkalinesoilsterrapreta.blogspot.com/ , I have just started second season TP experiments on a small scale on our Roof top in small pots
http://e-terrapretarooftopexp.blogspot.com/. The charcoal is exclusively from use of Magh-1 woodgas or smoke burner stove
http://e-smokeburnerstove.blogspot.com/ designed by me. I would like to share some of my immediate observations.

One day after establishing pots and the seed with soil and charcoal and only soil. I have sowed brinjal seeds in the 6 with charcoal + soil and 6 only soil. To my surprise I saw that in the three control pots the seeds were eaten away by small red ants. The six pots with a mix of about 30% charcoal were untouched by ants. In TP practice the chances of germination of the seed with out any loss to creatures like ants is minimized. I thought this is the first direct benefit of using charcoal. On day two I saw that all the pots without charcoal are with small red ants. There is not a single ant in the pot with charcoal addition.

Although I love ants, to avoid ants eating away the seeds sown, we could always add some charcoal along with the seeds. Second important application is that in the Vermicompost pits some ants eat away the earthworms to avoid such problem and for value addition to the compost to create a habitat for microbes, we could as well add charcoal.

From web I learnt that those you want to avoid toxic chemicals are using charcoal and diatomous earth as a repellant for ants. For photographs please see the blog below.

I would like to know from your experiences what could be the other impacts in using Charcoal to the living things existing in soil.

Dr. N. Sai Bhaskar Reddy

The fines of rice hull ash mixed in with stored seeds are very effective in controlling weevils. (Rice hulls have a very high silica content.) The sharp silica structures in the ash scratch the cutinous exoskelton of the first insects to emerge, leaving them to dessicate before they can breed and lay more eggs. (I was taught this in a weekend course by the Tropical Products Insitute, U.K.)

DE (diatomaceous earth) will do the same because of its silica edges, and is also used for pest control in storing grain. It is also recommended to add DE to compost for the same reason: it is not injurious to beneficials in the process like the digestive tract of worms, but will control certain pests that like to colonize compost

Could it be that the charcoal has similar cystalline structures which keeps the insects away...in fear of being scratched to death...?

Gerald Van Koeverden vnkvrdn at yahoo.ca

According to a old research study, the effect of charcoal fines on insects might have nothing to do with it as an abrasive or 'scratchy'medium. This article shows that certain dusts actually absorb the lipoid layer from the exoskelton of bees without any apparent abrasion, resulting in the dehydration of the insect. The results (Table 1) show that all the dusts effected an increase in the rate of water-loss of the dead bees; that the three most effective dusts were silica gel, Almicide and activated charcoal, the common physical property of these materials being their capacity to act as powerful absorbents; that Bentonite and activated charcoal, both soft materials, were more effective than carborundum, which is hard and highly abrasive. These facts again indicate that abrasion is not an important factor in the action of these dusts in disrupting the waterproofing layers, and suggest furthermore that they may act by adsorbing the lipoid material.


Dear Gerrit
Thanx for this interesting paper.

Activated charcoal (from gas mask 300 mesh about 50 micron) is very much different than TP. Activated charcoal is an aggressive - powerful absorbent with specific surface area BET 650-1200 m2/g, while TP is mild with specific surface area BET 25-100 m2/g, As far as I know CALCON Carbon tried to put in activated carbon to soil since long time, but was not successful.

Sincerely yours: Edward Someus (environmental engineer)
Terra Humana Clean Tech Ltd. (ISO 9001/ISO 14001)
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