[Terrapreta] Abstract on Charcoal in soil

[Saibhaskar Nakka]

Dear Kevin,

Thank you very much for your valuable suggestion. This area is drought prone
and receiving very less rain fall year after year, there is a total
reduction of 20 centimeters (from 80 cms in 1950's to < 60 cms presently).
The Climate Change / variability, over extraction of groundwater and
application of complex chemical fertilizers and high temperature conditions,
and seasonal rainfall, extraction of groundwater for paddy and flood
irrigation, etc. resulted in the alkalinity of the soils.

The option of using ever depleting meager groundwater resources for treating
the alkaline soils is a rare option.

The traditionally people were using Gypsum / sand / green mulching methods
to treat alkaline soils. And also traditionally people believed that the
burning of the crop residue in the fields benefited their soil. Some farmers
also brought the ash+soil from the Brick making kilns and they were
applying. That could be the reason why when discussed farmers were ready to
apply the  combination of (partial biochar+char+ash+burnt soil) for their
alkaline soils. Probably the resultant soil could(?) be with pH neutral (?)
+ phosphorous, calcium and  iron, more soil moisture retention capability,
changing the texture of the soil to soft (rather than hard kankar), etc.
These are the expectations, more over the green mulching and addition of
little gypsum will be encouraged. I believe Terra Preta could be a solution
for alkaline soils too (?). Thanking you once again.

Dr. N. Sai Bhaskar Reddy


On 5/16/07, Kevin Chisholm <kchisholm at ca.inter.net> wrote:
>
> PERSONAL
>
> Dear Dr. Reddy
>
> Pardon my brashness, but I can't see any way that Terra Preta would help
> with your alkaline soil problem. Can you propose a rational mechanism by
> which the Terra Preta could help?
>
> My understanding is that you can reclaim alkaline soils using gypsum as
> soil treatment.
>
> The basic reaction is:
> CaSO4 + Na2CO3 --> CaCO3 + Na2SO4
>
> The thing is that the Na2SO4 is more soluble than Na2CO3 and can be
> washed away from the soil. Actually, I don't know if it is so much a
> solubility issue, as it is a "bound" versus "unbound" issue.
>
> Hopefully, the Farmers have sufficient water that they can "irrigate
> away" the Na2SO4. If not, it might be possible to add the gypsum one
> year, and then develop a washing process to lift soil into a tankage
> system for agitation and washing.
>
> Best wishes,
>
> Kevin
>
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