[Terrapreta] Black soil

[MFH]

Richard - no, not parallel at all.

 

I did have some analysis data from the pumice layer after the '94 eruption -
will try and locate. However, we wanted to prove that it didn't need 10
years for some vegetation recovery on this material. Our first demo site was
within a kilometre of one of the volcanos which blew, and some 3 months
after it had quietened down. We chose a legume called Glyricidia sepium,
which is used extensively as a shade for cocoa during the seedling stages.
Grows rapidly, produces a canopy early, sheds masses of leaves as mulch,
puts N into the soil and is easy to propagate under these conditions - like
leave a cut branch lying on the ground and it will shoot.

 

Normally its planted by thrusting a sharpened stake about 1m long and 25mm+
diam into the soil. Simple as that. However for the reclamation project we
dug holes about 150mm deep and filled with soil we had taken from the source
of the Glyricidia stakes. This gave growth rates in excess of 2:1 as
compared to the control sites without added soil. At spacings of 2m and rows
of 3m, a canopy formed within 6 months.

 

The amount of soil added wasn't sufficient in its own right to account for
the added vigour. Assumption is that along with the nutrients in the soil we
added were all the little critters that aided a breakdown of the pumice. I'm
only sorry that I didn't know about char then. But there are some
similarities between char and pumice in respect of pores and surface areas,
and also in respect of not sinking. Pumice floated on Rabaul Harbour for
over a year, and apparently there were rafts of pumice in the Pacific for 10
years after Krakatoa. Many orchidists prefer pumice to charcoal.

 

Max H

 

 

 

 

  _____  

From: Richard Haard [mailto:richrd at nas.com] 
Sent: Wednesday, 4 June 2008 2:00 PM
To: MFH
Cc: 'Kevin Chisholm'; 'Philip Small'; 'Terrapreta'
Subject: Re: [Terrapreta] Black soil

 

Very interesting story Max, thank you

 

Have you done a mineral nutrient profile of the pumice parent material? 

 

I'm not a soil scientist but what I understand is the Amazon Oxysols  are
highly weathered, leached iron rich soils. Organic matter does not
accumulate and nutrients are easily lost by means of leaching. In natural
vegetation it is only biomass capture that retains these nutrients,
recycling as leaves fall during the dry season.

 

Are you certain this is a parallel situation?

 

Rich

On Jun 3, 2008, at 8:27 PM, MFH wrote:





There must be areas of the Amazon with a similar climate, and with similar
inert base soils. It seems that the Amazonians chose to improve their soils
by adding char whereas the PNG's basically let nature take its course.
Irrespective they both had an apparent understanding of the benefits of
living soil, a fact that seems to have escaped many industrial farmers.

 

Max H

 

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