[Market-farming] organic compost/humus
road's end farm
organic101 at linkny.com
Mon Oct 1 19:04:47 EDT 2007
On Oct 1, 2007, at 12:26 PM, David Guthrie wrote:
> i've used the bagged compost and humus from wal-mart and related
> stores and wondered if there might be heavy metals or other
> undesirables in the mix...
>
> anyone have an idea?
>
I would be suspicious of that as well. I think some sewage sludge
materials are still on the market, and they may well have such
problems; as might any compost or topsoil if the producers of it aren't
careful about possible contamination of their sources. You could try
asking the store and/or the company producing the stuff for a complete
analysis, including heavy metal levels; I don't know whether you'll be
able to get one, or whether the material in the specific bag you've got
is likely to be the same as the material they ran the analysis on, as
their ingredient sources may vary. If you can't get such an analysis at
all, I'd be very suspicious; the store might not have it, but the
manufacturer ought to.
Most pesticides don't survive the composting process, but some do; for
instance, the herbicide clopyralid can survive composting and has been
known to cause problems for crops that the compost was applied to. Your
extension agency might be able to tell you what could be a problem, and
you could ask for test results for those too; of course, you'd need to
know where the stuff originally came from to find out what might be in
use there. They could probably also run some basic tests on the stuff
for you for not too much money, at least for lead and maybe another
couple of the most likely problems.
There are bagged composts etc. acceptable for organic certification,
and those should be OK; but they're often hard to find. Watch out for
labels that are using the word "organic" just in the sense of "organic
matter"; that doesn't necessarily mean that they're acceptable. The
brand I use says "Approved for organic crop production". I also have to
check specific brands with my certifier; while those not certified of
course don't have to do that, an organic certification agency operating
in your area might be a good source of info for approvable brands.
-- Rivka; Finger Lakes NY, Zone 5 mostly
Fresh-market organic produce, small scale
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