[Digestion] Re Digestate as fertilizer

[Alexander Eaton]

Peter and All,

We are testing our digestate now.  Can you send us some of the laboratory
analysis you mention below for comparison?  Does anyone else want to share
digestate analysis?  It would be great to have a bank of data.  We are
trying to establish a market for this digestate (biol) in Mexico to make
small digesters more viable.  We want to understand the range in which the
material may fall so that we can provide some level of quality control.  We
are also experimenting with different feedstocks, and combinations to see if
we can further generate best practices for generating fertilizer appropriate
for different crops and uses (eg, pig manure digestate is great for corn
fields in fall, etc.).

Any data to use as a baseline would be appreciated.  This would also allow
us to see if our HRTs are correct and we are getting appropriate levels of
digestion.

Saludos,

ALex

On Thu, Nov 18, 2010 at 12:35 AM, P M Allison <pmallison at optusnet.com.au>wrote:

>  The use of digestate for crop fertilizers, is to me the very best option.
>
> The material contains all the nutrients required by plant-life as it is
> made up of the very same ingredients.
> Laboratory analysis of the spent material confirms this.
> A very similar substance is derived from vermiculture.
> The main problem with spent digestate is the fiber content. This will
> create nozzle lock-up on any spray delivery system. Fiber is not digested by
> anaerobes or worms.
> If the digestate is splayed too thick it will smother soil and emerging
> plants.
> The simple solution is to vibro filter the fiber and undigested material
> from the slurry. The solid matter is ideal for pelletizing and broadcast
> delivery.
> The resultant liquid component is a colloidal nutrient complex containing
> the same ingredients as the original material but in plant ready form.
> This liquid does contain particulate matter which can clog nozzles. My
> solution to this is to centrifuge the liquid and trap out the sedimentary
> material leaving a purely colloidal substance. This can be used as a foliar
> fertilizer when diluted with water as the substance is too rich to be used
> neat.
> The trapped debris is a rich nutrient mud, primordial ooze so to speak.
> This is also rich in nutrient and the finest of carbon flocs. An ideal
> binder for pelletizing the solid matter  initially extracted.
> By the way, the carbon flocs are the same as those used carbon-fiber
> production.
> Biogas is a wonderful bonus to the system, but should not be the be-all and
> end-all of the process. The spent material is the sort of substance which
> will make sustainable agriculture a much better option than what chemical
> farming will ever do. The crop improves, the soil improves, the soil biology
> improves, soil moisture holding capacity improves, soil carbon increases.
> Remember, it's the dark matter  which differentiates soil from being just
> lifeless dirt.
> Regards,
> Peter.
>
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-- 
Alexander Eaton
Sistema Biobolsa
IRRI-Mexico

Mex cel: (55) 11522786
US cel: 970 275 4505

alex at sistemabiobolsa.com
alexanderb.eaton at gmail.com
sistemabiobolsa.com
www.irrimexico.org
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