Actually, the recommendation is against human and pet feces. Large
animal feces, properly composted, is widely used and no organic
gardener would dream of doing without composted sheep, horse, or cow
manure in the mix.
Properly composted is the trick. Pathogens can survive most composting
methods. Pets can carry human pathogens and humans are susceptible to
some of the same pathogens as pets. As spores, pathogens can survive
extreme condition for a long time. While hot composting is better than
cold for destroying pathogens, temperature is at least as important as
time. Unless steam is coming off the compost, it's not hot enough.
Think about it. The heat is caused by the activity of microorganisms.
If they can survive those temperatures, so can some pathogens,
especially as spores.
I understand the recommendation to not use sewage sludge (Dillo dirt)
on a vegetable garden is due to the possible presence of chemical
contaminants. It is treated to kill pathogens. But a number of years
ago, I used sewage sludge on a flower bed and several tomato plants
sprang up. The seeds had survived composting and treatment!
Freelance Science Writer and Editor
Humans, as I have already pointed out, are large animals. Generally quite a
bit bigger than sheep or chickens, and occaisionally even weighing more
"Interestingly enough, the same trials indicated that bacterial pathogens
were destroyed whether the piles were turned or unturned, stating that
there was no evidence that bacterial populations were influenced by turning
schemes. There were no surviving E. coli or Salmonella strains, indicating
that there were ?no statistically significant effects attributable to
Actually, that's an urban myth. It just isn't true. Pathogen die off is a
function of temp x time. The longer a particular temp can be held, the
greater the die off at that temp. You probably want something above body
temperature but, if you can hold that temp for a few days (fairly easy in a
pile at least 3' on a side), then the temp doesn't have to be especially
Hmmm ... you do understand that various bacteria thrive at various temps,
don't you? Just as some organisms encyst or sporulate to escape a given
harsh environment, so do others un-encyst and become active. All these
bacteria are adept at hunting each other down for lunch.
Elliot, did you follow my suggestion to look up "humanure" on google? I
don't think anyone actually took the time to do that because the responses
don't reflect the knowledge available there.
Since you refer to yourself as a science writer, I'll use your post to
respond to several.
First of all, there is a difference between hot composting and slow
composting and this difference in methods results in different levels of
pathogen die off. Tomato seeds do not survive hot composting. They sprout
as the temp elevates and are then steamed to death as the temps continue to
rise. The process the sewage sludge goes through is cold composting. It is
sufficient to kill off most human pathogens (for reasons I list below), but
no attempt is made at actually sterilizing the soil against all forms of
Pathogens live at or near body temps. The bacteria that take compost above
body temps (I have measured a sustained 160 F. under a mantle of ice) are
dormant at body temps but are thermophilic ... that is, they love heat and
become active only when the temps become elevated.
I agree that animal feces (two legs or four) should not be applied to the
surface of the soil. From there, minute amounts can splash upwards during
rain or ordinary watering. Although subsequent drying and the UV of the sun
will kill off most of the few pathogens that are actually splashed up onto
edible portions, the course of caution is to avoid the practice of
spreading raw manure on the surface of soil planted to food crops.
However, none of these cautions apply to composted manures from any animal
source. Properly composted manures are 1) hot composted 2) aged 12-36
months following the final heating. The parasites that inhabit humans and
animals are well adapted to their role ... right down to requiring a
certain level of heat, nutrients and moisture to survive. Compost is
alternately too cold, then too hot and then too cold for them and, as time
goes by without access to mammal fluids, those not killed by the temp
extremes are done in by starvation.
I do not make radical statements blindly. Take a look at the website I
pointed to. I believe you'll find your thinking has changed long before you
get to the last page. I live in the city and would quickly find myself
fighting not only City Hall, but my wife, if I were to collect our manure
for our compost piles. But even she (with a degree in Environmental Health
Science) agrees that the material in the website makes powerfully good
Read the website if referenced. Its author does a much better job of
advocating the composting of human manures than I could. After all, he
wrote the book on it!
Now, if you'll excuse me, it's after 4 am and I need to be up to worship /
study in about 5 hours.
Zone 5b (Detroit, MI)
I operate my own mail server (Postfix on Mandrake Linux). The above address
My husband worked on site in the engineering office of a city agency for
many years. They always had tomato plants growing around the "pond"
because the tomato seeds were so "durable." Apparently, it takes a lot to
keep tomato seeds from surviving and sprouting, unless, of course, you
want them to grow. <g>
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