[Digestion] Digestate as fertilizer.

Wed Jun 29 22:13:20 CDT 2011

Dear List,
 The fact that the soil micro-organisms contribute to soil fertility is
accepted by all agricultural scientists. Logic tells us that high calorie,
non-composted organic matter would serve the microbes best as
nutrition. From this point of view, we conducted experiments and found that
plain sugar or pulped green leaves were excellent as soil amendments. The
rates of application were 25 kg dry matter per ha. Capillary water in the
soil always has soil minerals dissolved in it. When one applies a carbon
source to the soil, the microbes absorb the necessary soil minerals from the
capillary water. There is no need to add minerals through the organic
matter. That is why even plain sugar causes soil microbes to increase their
numbers. The concentration of minerals in the capillary water is at a
dynamic equilibrium. If a mineral molecule is removed from the capillary
water by a microbe, it is replaced by a molecule going into solution from
the un-dissolved pool of minerals in the soil. We have about 30 km of
earth's crust under our feet. New soil is being formed every day. Only 5% of
the dry weight of plants is constituted by minerals. Therefore there is an
unlimited supply of minerals in the soil. Don't think that it would ever get
exhausted by agriculture. And when you apply an organic manure to the soil,
don't calculate the NPK in it but count the nutritional calories in it.
Yours
A.D.Karve

On Wed, Jun 29, 2011 at 11:58 PM, Douglas Renk <douglasrenk at yahoo.com>wrote:

>      Hello "Gordon" :)
>
> I'm curious to see Peter's response to your question.
>
> Over and above the nutritional value of the digestate versus cost of
> separation and application, let's hope health and productivity of soil as a
> natural resource converts to monetary value. Soil's ability to sequester
> carbon is an ecological service that has been monetized.
>
> http://www.scribd.com/doc/49240018/lbfb-en
>
> I think as agricultural or bioprocess engineers, we are by nature,
> conditioned to think circularly. Therefore the total cost of an agricultural
> model should include all costs (which should include preservation of land,
> fertility and resources) to function as closely to a successful market model
> as possible.
>
>
> All the best,
> Doug Renk
>
> --- On *Wed, 6/29/11, Randy Mott <randymott at ceeres.eu>* wrote:
>
>
> From: Randy Mott <randymott at ceeres.eu>
> Subject: Re: [Digestion] Digestate as fertilizer.
> To: "'For Discussion of Anaerobic Digestion'" <
> digestion at lists.bioenergylists.org>
> Date: Wednesday, June 29, 2011, 2:05 AM
>
>  Okay. My nickname is the Gordon Gecko of biogas: cost per ton? Value of
> separate constituents per ton?
>
>
>
> Randy Mott
>
> CEERES
>
>
>
> *From:* digestion-bounces at lists.bioenergylists.org [mailto:
> digestion-bounces at lists.bioenergylists.org] *On Behalf Of *Peter Allison
> *Sent:* Wednesday, June 29, 2011 4:31 AM
> *To:* digestion
> *Subject:* Re: [Digestion] Digestate as fertilizer.
>
>
>
> Hi All,
>
> With regard to utilizing digestate as a crop fertilizer, it is often stated
> the slurry is spread on fields with the inherent problem of biological
> toxicity and crusting of surface applications.
>
> I believe this process is an incomplete and basically a cheap and nasty
> means of disposing a potentially valuable resource.
>
> The addition of a 1.5% potassium hydroxide solution of  to the spent
> digestate enables a disassociation of the solid fraction from the colloidal
> material. When the un-reacted and fibrous remains are filtered from the
> treated mix and the resultant fluid is allowed to settle, colloidal
> concentrate or fulvic acid will be found in the top fraction, humic acid in
> the lower portion and carbon rich nutrient at the bottom.
>
> The increased pH also enables a stabilization of biological activity within
> the fluids until dilution with water.
>
> These fractions are the most valuable components of the AD process. The
> bio-gas is a bonus.
>
> The fulvic acid is a supreme foliar fertilizer, the humic acid is best
> suited to soil applications and the carbon mud is an excellent binder for a
> wide range of solid crop fertilizer inclusions such as rock-dust, blood and
> bone, etc, before pelletizing for broadcast operations.
>
> We are desperately looking for sustainable solutions to chemical based crop
> fertilizers. Most agriculturalists are aware of the folly of NPK reliance.
>
> AD, like the composting of organic waste materials provides all of the
> nutritional requirements for every form of plant-life.
>
> Recycling of crop nutrients via AD has the ability to negate the
> detrimental effects of chemical agriculture, repair degraded soils, help
> resolve salinity problems, increase nutritional food values of crops,
> increase soil moisture holding capacity and put an end to the contamination
> of precious waterways.
>
> Simply dumping spent digestate on fields is a lazy and mindless means for
> disposal.
>
> Don't waste waste.
>
> Regards,
>
> Peter.
>
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>
>
>

-- 
***
Dr. A.D. Karve
President, Appropriate Rural Technology Institute (ARTI)

*Please change my email address in your records to: adkarve at gmail.com *
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