[Terrapreta] Soil Food Web

[Michael Bailes]

> *Tropical soils have a humus content of about 1.8% by volume, or less. By
> comparison: New York and Ohio are 10-12%, Iowa is 15%. [my emphasis]
>
> *It seems to me that charcoal is the only substance that, hopefully, gives
> the soil the proper *structure* (when heat, humidity or other oxidizing
> agents are present) to keep humus, nutrient and moisture available to be
> used by food crops.
>
>  Yes many Australian soils often have a humus content of less that 3%
http://209.85.173.104/search?q=cache:jTuK20dpC2sJ:www.biodynamics.net.au/documents/PlainOldDirt-Compactversion2006edn..doc+humus+content+of+Australian+Soils&hl=en&ct=clnk&cd=8&gl=au&client=firefox-a

This is an interesting sum from the same article

> For the purpose of developing a broad scale and practical model for
> estimating increases in water-holding capacity for given increases in *
> humus* at a catchment level it is suggested that a 1% increase in soil *
> humus* will result in a 4% increase in stored soil water

*5.2 Water-Holding Capacity Increase for One Hectare for Varying Levels of
> Humus Increase*
>
>
> Using the guideline ratio, which has been established for additional water
> retention the following gains can be expected.
>
> *Humus* Increase            Increased Volume of Water Retained /ha (30 cm)
>
>          (OC% x 4,000,000kg x 4)
>
> 0.5%       80,000 litres  ( average 2004 level)
>
> 1 %      160,000 litres
>
> 2 %      320,000 litres
>
> 3 %      480,000 litres
>
> 4 %      640,000 litres
>
> 5 %      800,000 litres  (pre-settlement level)
>
> The Clarence Valley catchment has an area of 2,300,000 ha², a 0.5% increase
> in *humus* (organic carbon) would therefore store an additional
> 184,000,000,000 litres of water following an adequate rainfall event.
>
.
> http://209.85.173.104/search?q=cache:jTuK20dpC2sJ:www.biodynamics.net.au/documents/PlainOldDirt-Compactversion2006edn..doc+humus+content+of+Australian+Soils&hl=en&ct=clnk&cd=8&gl=au&client=firefox-a



-- 
Michael the Archangel
"Politicians will never solve The Problem;
because they don't realise they are The Problem.".
-Robert ( Bob ) Parsons 1995
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