permaculture

["Lawrence F. London, Jr." <lfl@intrex.net>]

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Subject: Re: Purity Of Organic Foods/Compost
Date: Sun, 24 Nov 2002 08:51:47 EST
From: Elaine Ingham <Soilfoodweb@AOL.COM>
To: SANET-MG@LISTS.IFAS.UFL.EDU


Luckily, when you take leaves contaminated with who-knows-what pesticide
and compost them, letting the microorganisms do their thing, the
microbes chew up the pesticides, turning them into carbon dioxide,
water, more microbial biomass and some waste materials that are then
used by other microbes.

The important thing is to make sure you maximize the DIVERSITY of
microbes in your compost, so you are most likely to have the microbes
needed to chew up the pesticides.   You also need a diversity of food
resources, that is, kinds of organic matter, so you have the diversity
of foods that the diverse set of microbes need to do their jobs.

The more diverse, the more likely you will get decomposition of toxic
chemicals.  We're talking diversity of BOTH plant material and microbes
here.  And a couple more things are needed....

Typically you need some temperature in your compost pile so the microbes
have the energy to decompose the difficult chemical structures of
pesticides.  All those chlorines and bromines and benzene rings in most
pesticides require production of seriously high-energy-requiring enzymes
to allow break-down of the pesticide.

But that's the right amount of heat - not too much, not too little.  If
you see "compost" that has turned black, the composter fried the most
important critters, and the pesticides are probably still present.
Compost is supposed to be dark brown, not black.  Nor do the pesticides
generally decompose if the compost turns anaerobic.  So, stinky, smelly
compost is not compost.  If it smells bad, it means something is not
right.  Don't put it around your plants.  Learn what is a bad odor,
versus a soil smell.   You may need a course in composting from someone
who knows something about these smells and what they mean.

So, you have to have water and air correct in your pile.  More
"not-too-much, not-too-little" factors.  We need air and water just
right - the Goldilocks principle.  Compost is not a simple linear
system, multiple factors have to be correct all at the same time.  Water
influences the amount of air present.  Too wet, and you go anaerobic.
Too dry, and the microbes are sound asleep. Must get it just right.
-----
Heavy metals may be sequestered, or tied up in organic forms in compost,
in forms that all but the most destructive chemical analysis will not
detect.  Heavy metals stay plant-not-available if you maintain the
organic matter level in your soil.  You lose organic matter in your soil
most rapidly when you plow or physically disturb soil.  Minimize
tillage, and you minimize organic matter loss.  Maintain organic matter,
and heavy metals remain immobile and not-plant-available.

Does that mean you should never till?  I said, minimize tillage.  Till
to the least extent possible.  Vern Cole and Bobby Brock have both shown
this to be the case, along with quite a number of researchers that
followed on their leads.  Minimize tillage.

Residues left in your field in the fall should be decomposed by the
microbes, not sliced and diced and plowed into the soil.  If your
residues do not "disappear", there's something wrong with the set of
microbes in your soil, and you need to fix them and get them working for
you again.  If you till residues into the soil, they may just produce
plant-toxic compounds if they decompose without enough air in compacted
soil.

But back to pesticides in compost.  We have a recent addition to the
herbicide world that apparently does not decompose during the composting
process.  Chlopyralid is a serious problem, and this chemical should be
banned from ever being put on another ecosystem.  Nothing decomposes it,
and once you put it on your lawn, you will not be able to convert that
lawn into a vegetable garden or into broad leaf plant production.  I'm
rooting for the little critters, however, and hoping that somewhere,
someone will find the microbe that will decompose chlopyralid.  For more
information on the topic, please look at the City of Seattle's website,
and the writings of David McDonald from Seattle.  I recall that Steve
Diver from ATTRA has put together a good reference list on this topic as
well.  Check www.ATTRA.org

To summarize then, to get the decomposition of toxic chemicals in your
compost, you have to have the right microbes, good food for them,
correct air/water mix and additional energy, such as heat, or passage
through an earthworm.  Then, you can feel pretty safe about the "purity"
of your compost.

One last point - In Europe, we almost invariably have to add the right
set of microbes to compost piles, because in most places, the plant
material no longer has the desired set of microbes on the plant
material.  In the US, in the major cities, the same problem occurs quite
often.  The plant material does not contain the necessary set of
organisms that decompose pesticides.  An inoculum of beneficial microbes
is needed.  Commercial composters find that adding back a little of the
last pile, or adding a commercially available inoculum of microbes, is
necessary.  Add organisms to make sure the minimum diversity is
present.   This says something that should be of concern to everyone
about the wide-spread presence, use and impact of pollutants in the
world.

At Soil Foodweb Inc, we will be offering assays to allow people to
determine whether they have the beneficial organisms in their soil,
compost or compost tea.  The ability to determine presence of beneficial
organisms is not available elsewhere.  Check our website for more
information.

Elaine Ingham
President, Soil Foodweb Inc.
www.soilfoodweb.com