Because of Midwest Bio-Systems' belief that compost
should be a highly beneficial product for the soil and plant, we
have never limited ourselves to the usual government or industry standards
for determining compost value.
Government entities addressing the issue of compost standards take a "public
health" approach to compost. Their regulations will invariably be concerned
with what is not in the compost — disease pathogens,
heavy metals, and other "constituents of concern." So a "Grade
A" or "Class 1" label can be applied in many places where
the only criterion is what's not in it. Such an approach tells us little
about a compost's benefit to the soil and plant.
Secondly, there is a "waste management" approach. It essentially
wishes to reduce the volume of organic waste, which composting does well,
and "make it disappear."
 Composting
organizations take a broader view and show deeper interest in the soil value
of the compost product. Composting organizations were, however, not formed
to promote one form of composting over another, but to advance the concept
and practice of composting in general. It behooves them to adopt standards
which their members will accept and embrace.
In states where attempts have been made towards adopting demanding criteria,
organization officials typically find the veteran composters balking. Little
have they realized that the commitment to excellence would multiply the
value of their finished product both at the marketplace and in the soil.
Beyond the public health and waste management issues, compost organizations
have succeeded in identifying middle ground acceptable to their constituents
for definitions of quality. Tests such as pH, soluble salts, an NPK approach
to nutrient content, moisture levels, organic matter, maturity (phytotoxicity),
stability, and particle size may be included.
This is good and valuable information. Nevertheless it lacks the measure
of quality we (MBS) require to call a finished product, ACS Quality.
Remember our purpose is to beneficially affect plant roots now
as well as energy and nutrient conversion months from now.
Midwest
Bio-Systems determines compost quality by:
•
What the profile of the microbiological assay shows regarding the finished
compost product (diversity of species, enumeration of microbes, and aerobic:anaerobic
ratios)?
•
How soil health is improved
•
How crop yield is increased
•
How plant health is enhanced
•
How production costs are reduced while simultaneously generating additional
income.
What should be included in these optimum standards?
• Sulfides and sulfates:
A quality compost should test 0 parts per million (ppm) for sulfides at
all times. The producer wants the sulfur in his product to break down
with oxygen and form sulfates. A process which has become anaerobic
causes sulfur to break down with hydrogen and form sulfides, which can
be toxic to plant life and hinder microbial proliferation.
• The nitrogen process: Our goal is to have nitrogen
in the nitrate form NO3 at levels
in the 600-900 ppm range. Many composters focus on %N and interpret value
in the soil by the level of N. This approach does not look at in what
form the N is held. Is it unstable and odor producing ammonia
or the stable and odorless nitrate? Users err in evaluating compost by
the same criteria they use to evaluate a fertilizer. The compost user
does not amend the soil for the purpose of nutrient content as much as
for introducing beneficial biological activity, which also impacts soil
physics and chemistry. Vicki Bess of BBC Labs in Tempe, AZ writes in her
literature, "Populations of these free living nitrogen-fixing bacteria
will proliferate as the available nitrogen in the compost decreases. As
a consequence there is typically an inverse relationship between biologically
available nitrogen in the compost and the concentration of free living
nitrogen-fixing bacteria." Those beneficial bacteria are what the
compost end user covets.
In compost, N-P-K and trace elements
are encapsulated in the humus and stored until beckoned by the plant—thus
producing high energy with long term beneficial plant growth, if the humification
process is proper.
• Conductivity: Many composters across the country
and around the world treat high salt levels as an impassable barrier.
But again, an effective humification process allows effective transformation
of many salt ions in manure and other compost feedstocks to a benign substance.
It is critical to have sufficient negatively charged ions present in the
compost windrow. If the composter does not endeavor to get his windrows
into the humification phase, the salt problem in the soil will worsen.
We have observed soil sodium levels go from 799 ppm (before ACS compost
was applied) to 53 ppm after ACS compost was applied (rate of 7 tons/acre)
while the accompanying base saturation percentage of sodium lowered from
over 29% to below 3%. The quality of the compost makes the difference.
• Redox potential:
A redox reading outside the desired 26-29 range indicates the materials
have variously gone anaerobic, too
dry, or too wet.
• Microbiology analysis: Here we learn what is
in the compost. The greater the diversity and quantity of beneficial microbes,
the more valuable and effective the compost will be in disease, weed,
and insect suppression.
We would like to see at least a 10:1 ratio of aerobic to anaerobic bacteria
(ten aerobes for every one anaerobe). We learn about the number of fungi,
actinomycetes, pseudomonads,
and nitrogen-fixing bacteria living in the compost from the microbiological
assay.
Diversity promotes numerous interspecies relationships and interactions.
More varied and flexible response to environmental stresses and fluctuations
are therefore possible.
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