By Wayne McLaurin
University of Georgia
Volume XXVIII
|
E. coli isn’t just for hamburger lovers anymore. Newer
strains of this deadly
pathogen make applying fresh manure to food gardens truly
risky.
When is it dangerous?
Not all manure carries the newer bacterial strains. But
there’s no way to tell
without extensive lab testing. A child’s death in Maine was
traced to E. coli
0157:H7 from calf manure added to the family garden.
Using aged manure for turf and ornamental plants isn’t a
problem. Amending
vegetable gardens with plant-based compost, sphagnum peat or
well-composted
manure, too, is still good to do.
Bacteria-contaminated vegetables fresh from the garden affect
people largely
because the produce is poorly washed. Adults generally become
ill and recover.
But the organism can be life-threatening to children and the
elderly.
Lettuce seems particularly subject to carrying bacteria,
because it’s succulent
and hard to wash.
With carrots and other vegetables, scrubbing and peeling them
before eating
them greatly reduces the chances of bacterial contamination.
Safe food-handling
practices are now more important than ever.
Using manure safely
In home gardens, make sure all manure is well-composted for
at least 120 days
before adding it to soil where vegetables or fruits are
growing.
Bacteria will survive winter freezing. So fall garden
applications and even
adding “aged manure” provide no guarantee of a garden free of
disease organisms.
The heat produced through proper composting will kill most
pathogens. The compost
should heat to 130 or 140 degrees for five days or more to be
more effective.
Even so, research has shown that a certain percentage of the
pathogens can survive.
Following the hot-compost phase, a “curing” time of two to
four months allows
beneficial microbes to outcompete disease pathogens. This
produces an acceptable
organic soil amendment.
Note that compost made solely from plant wastes doesn’t need
a curing period.
And it’s safe to add leaves or other plant matter directly to
the garden.
