Dear Mr. Ellingsen, one puts organic substances into the soil primarily as food for the soil microbes, so that they increase their numbers. All agronomists agree that there exists a direct positive correlation between the population density of microbes in the soil and soil fertility. Therefore, one must feed them with high calorie organic matter and not with compost that has very low calorific value. As far as biogas slurry is concerned, its value as nutrition to the soil microbes would depend on the feedstock that originally went into the biogas plant. If it was human food, it would get completely converted into methane and carbon dioxide, and the residue would hardly contain any organic matter that would serve the soil micro-organisms as food. If the feedstock were dung of cattle, which had received leafy biomass as feed, the slurry would mainly consist of lignin arising from the midribs and veins. Application of such a slury to a field would cause the lignin digesting fungi to multiply in the soil. One can of course look at biogas slurry as a source of inorganic nutrients, but in that case, one would have to apply fairly large quantities of slurry to match the quantities of NPK that a crop needs. A back-of-the-envelop calculation shows that one must compost the biomass from about 10 ha to provide one ha with the necessary NPK. Yours A.D.Karve
On Wed, Jul 13, 2011 at 3:41 PM, Johan Ellingsen < [email protected]> wrote: > I am a 62 years old Norwegian senior adviser in a Norwegian NGO called > Norges Vel (The Royal Norwegian Society for Development). I am working with > environmental projects within organic farming and climate change. I am an > engineer in chemistry and have been working with agriculture for 30 years, > also on my own organic farm 30 km outside of Oslo. The farm was organic in > 1989. We had animals for 10 years, but today we only have cereals and green > manure. I hope that a new biogas plant for the city of Oslo can provide > the farm with digestate. I see an unique option to recycle organic food > waste through digesting in a biogas plant, if the quality is acceptable for > organic farming.. **** > > ** ** > > *JOHAN G. ELLINGSEN* > > Seniorrådgiver**** > > Dir. tlf: + 47 64832035**** > > Mobil: + 47 90921568**** > > [email protected] > > Postboks 115, N-2026 Skjetten**** > > Telefaks: +47 64 83 20 01**** > > www.norgesvel.no > > [image: Beskrivelse: cid:[email protected]]**** > > ** ** > > ** ** > > _______________________________________________ > Digestion mailing list > > to Send a Message to the list, use the email address > [email protected] > > to UNSUBSCRIBE or Change your List Settings use the web page > > http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org > > for more information about digestion, see > Beginner's Guide to Biogas > http://www.adelaide.edu.au/biogas/ > and the Biogas Wiki http://biogas.wikispaces.com/ > > > -- *** Dr. A.D. Karve President, Appropriate Rural Technology Institute (ARTI) *Please change my email address in your records to: [email protected] *
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_______________________________________________ Digestion mailing list to Send a Message to the list, use the email address [email protected] to UNSUBSCRIBE or Change your List Settings use the web page http://lists.bioenergylists.org/mailman/listinfo/digestion_lists.bioenergylists.org for more information about digestion, see Beginner's Guide to Biogas http://www.adelaide.edu.au/biogas/ and the Biogas Wiki http://biogas.wikispaces.com/
