[Digestion] vermiculture of digested solids

[David Fulford]

Dear Theo and readers,

The people using vermiculture with biogas digestate claim that it 
further improves the fertilizer value of the compost. When I visited a 
village that was using the system, we met a commercial coconut grower 
who was prepared to pay in cash the equivalent of $60 per tonne for the 
compost from the vermiculture unit. The farmers claim an increase in 
production of 30% over three years of using the compost, as well as 
improved quality of the produce (rice, millet, ginger, potatoes, 
vegetables, coconuts and  betel nut trees). The growers said they saw is 
a much reduced drop of immature nuts from coconut and betel nut trees 
when they used vermiculture compost.

The digestate is added to dry biomass material (leaves, grass, old grass 
mats etc.), so the liquid is absorbed into the compost. The mix is 
allowed to aerobically compost for about 3 to 4 weeks before the worms 
are added. This process allows a much increased amount of compost than 
is available from just the digestate and it allows the liquid component 
of the digestate to be absorbed.

In India, when the digestate is used on its own, the liquid often 
evaporates, with a loss of nitrogen in the form of ammonia. The 
digestate is usually left in a lagoon until it is required, as it needs 
to "mature" before it can be used.  Absorbing the liquid component in 
dry biomass allows the nitrogen to be retained.

The vermiculture material is kept moist with water, to give the worms 
the right conditions. Excess water is drained off and the liquid can be 
used as a foliar feed. It is claimed that it repels pests and improves 
plant health.

Regards,

David F

On 11/11/2010 23:09, Theo Bijman wrote:
>
> Dear readers,
>
> Referring to the question about vermiculture.  Why should you want to 
> use vermiculture when you have already digested solid waste that could 
> be applied to the fields directly? With raw manure, I could see the 
> advantage, as you would get a somewhat dry, concentrated and easy to 
> apply organic fertilizer, without the acidifying effect of manure. Is 
> it the reduction in volume that is an advantage?  Or are people used 
> to using vermiculture organic fertilizer and do not know the usage of 
> digested solid waste? Maybe somebody has some thoughts about this. Do 
> you apply liquid waste to the composting heaps  (the liquids which 
> remains when separating digistate into solids and liquids?) to keep it 
> moist?
>
> Thanks
>
> Theo Bijman
>
> Matt and listers, Hello,
>
> There are two projects in South India doing vermiculture of digestate: 
> SKG Sangha and VK-Nardep that have been highlighted on the list, as 
> they both won Ashden Awards. There are videos available for both 
> projects, although the one for VK-Nardep is a sequence of still 
> photographs taken at the time of the judge's visit.
>
> The Ashden Award links are: www.ashdenawards.org/winners/skgsangha 
> <http://www.ashdenawards.org/winners/skgsangha>and 
> www.ashdenawards.org/winners/vknardep 
> <http://www.ashdenawards.org/winners/vknardep>. A direct link to SKG 
> Sangha is: www.skgsangha.org <http://www.skgsangha.org>and to 
> VK-Nardep is: vknardep.org <http://vknardep.org>.
>
> Regards,
>
> David Fulford
>
> On 11/11/2010 01:33, Matt Lorig wrote:
>
> There was a project mentioned on the list (maybe a year or two ago) 
> about a vermiculture project using the digestate from a biogas plant.  
> I think it was in India.  I think they were using sawdust to soak up 
> the water and composting it for a period of time and then introducing 
> the worms.  I can't find the link now.  Does anyone remember what I'm 
> talking about?  Or does anyone have any info about vermiculture 
> combined with biogas?
>
> Matt Lorig
> mattlorig at yahoo.com <mailto:mattlorig at yahoo.com>
>
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> http://www.adelaide.edu.au/biogas/
> and the Biogas Wiki http://biogas.wikispaces.com/
-- 

********************************************************************
Dr David Fulford CEnv MEI, 15, Brandon Ave, Woodley, Reading RG5 4PU
d.j.fulford at btinternet.com <mailto:d.j.fulford at btinternet.com>, Tel: 
+44(0)118 326 9779 Mob: +44(0)7746 806401
Kingdom Bioenergy Ltd, www.kingdombio.com <http://www.kingdombio.com>, 
davidf at kindombio.com <mailto:davidf at kindombio.com>

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