[USCC] Oxygen in Active Compost

[Cary Oshins]

John,
I have seen you write many times on your research and what it takes to
maintain a fully aerobic compost mass. It is fascinating and instructive
research, for sure. My question is, at the end of the day, when you have
fully mature compost, what are the differences between compost that was kept
fully aerobic and compost that was partially aerobic? Not just what are the
measurable differences, but under what conditions (ie, uses) does it
actually matter? 

Cary Oshins
GARDENIQUE Landscaping, Inc.
610-972-9018
www.filtrexx.com
Filtrexx—Our Soxx don’t fall down!

-----Original Message-----
From: compost-bounces at composter.com [mailto:compost-bounces at composter.com]
On Behalf Of John A. Crockett
Sent: Sunday, February 04, 2007 12:10 PM
To: U.S. Composting Council listserve
Subject: [USCC] Oxygen in Active Compost

How much Oxygen do the microbes in early stage active compost need?

I've heard some people claim that 5% oxygen in aerobic.  Our own hands on
research, in our own lab, based on direct estimates of the population of
active bacteria, based on serial dilutions in phosphate buffer, then
staining with FDA, and actually counting under 1000X, using Epi Fluorescence
microscopy, so far we've never had, with the compost feedstocks that we're
working with, over 3 billion active bacteria, per gram, dry weight, when the
CO2 level in the off-gas was over 4%, which means the oxygen was likely
16-17%.  Thus, our own definition for "aerobic" is oxygen of 17% or more,
and / or CO2 less than 2%.

We frequently measure the rate of air flow in our compost research silos,
and frequently, to hold the oxygen level > 17% requires that we move a
volume of fresh air through the compost EVERY HOUR, over twenty times the
volume of compost.  While that seems like a lot of air, we've replicated
that research probably close to a hundred times, so we have the hard data,
from our own research in our own lab.  Is this sort of research expensive?
Of course it is expensive.  And we believe that relying on claims that
windrows will aerate by convection, or that turning will keep the compost
aerobic, or that 5% oxygen is good enough, is far more expensive.  

Much of our research is presented on our website, in easy to understand
graphs.  If you know of research that indicates different conclusions, we'd
like to know about it.  

Working Together to Create a Sustainable Environment,
John A. Crockett, a.k.a. Dr. Mike Robe
Mother Nature's Farms, Inc.
(845) 225-7763
http://www.magicsoil.com/
jac at magicsoil.com