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Re: Purity Of Organic Foods/Compost

Municipal yard waste consists of grass clippings, leaves,
and shredded tree timmings.

Of these, grass clippings are the only biomass source
with pesticide contamination levels of any concern,
for all practical purposes.

Tree leaves are rarely sprayed with pesticides.  A few tree
species, for example sycamore, will sometimes receive a
fungicide spray to control anthracnose, but that is way back in
early spring.

Shredded branch timmings actually make a valueable compost

Some of the woodier and bulker wood chips provide porosity
and air flow, while the shredded feedstock derived from young
green branches helps balance the C:N ratio; and the lignins from
these young branches may play a role in humification.

Leaf recycling by communities, gardeners, and small farmers
is a great way to generate biomass for use as a mulch and
to make compost.

Leaves are a local biomass source, they are free, and they
are available in large volumes.

Leaves are free spirited and will blow away, though, so that is
why Master Composters talk rounding them up and keeping
them pinned down in a leaf corral.

If you have a 3' x 3' pile of leaves, and one 50-lb
bag of alfalfa pellets (rabbit feed), then you have the
perfect C:N ratio for a thermophyllic compost pile;
just sprinkle rabbit pellets and water as you build the
pile of leaves, then turn after one week to re-mix
and re-moisten the pile.  Repeat the turning process
a few times.  Later, after temperatures are moderate,
you can add worms and let them do their thing, which
adds another biological dimension.

When it comes to organic farms and municipal yardwaste,
in relation to concerns over pesticide contaimination of
grass clippings, an easy solution is to just collect leaves and
branch trimmings in the fall and completely avoid grass

Yet when it comes down to mixed yardwastes with grass
clippings and potential herbicide residues, there is good reason
to expect the composting process itself to pack a powerful
punch full of enzymes and microbial bioremediation processes.

Phil Fredericks at EarthCare Technologies, Inc. is the compost
manager who has a lot to say about the compost windrow
functioning as a bioremediation factory.   He uses specialized
microbial inoculants to enhance degradation of hydrocarbons
and waste products handled at his compost facility.  The basis
of this microbial technology goes back to oilfeed research
in Oklahoma in the 1960s.

Staff at Alberta Agriculture, Food and Rural Development
(AAFRD) developed a database of references on composting
and put this online as:

On-Farm Composting - A Review of the Literature

Included is this topic:

On-Farm Composting: Bioremediation / Soil Remediation

For a recent literature review on the occurrence, degradation,
and fate of pesticides in composts, see this two-part series in
Compost Science and Utilization.

Occurrence, Degradation, and Fate of Pesticides During
Composting || Part I: Composting, Pesticides, and Pesticide
Degradation (Literature Review)
Fatih Büyüksönmez, Robert Rynk, Thomas F. Hess and
Edward Bechinski
Compost Science and Utilization (1999) | Autumn | Vol. 7, No.4 |
pages 66-82.

Occurence, Degradation, and Fate of Pesticides During
Composting || Part II: Occurence and Fate of Pesticides in
Compost and Composting Systems (Literature Review)
Fatih Büyüksönmez, Robert Rynk, Thomas F. Hess and
Edward Bechinski
Compost Science and Utilization (2000) | Winter | Vol. 8, No. 1 |
pages 61- 81.

Compost Science and Utilization

Steve Diver