Re: [compost_tea] function of protozoa

From: Robert Norsen <bnbrew_at_yahoo.com>
Date: Sun, 7 Dec 2003 22:33:39 -0800 (PST)

Somebody suggested the Nitrigen released by the bacteria might be brown. I undersand that is not true. It is more like watermelon rinds and corncobs. The part the protozoa don't eat that is left for the plants. But unless something eats the bacteria there aren't any corncobs..
 
Excuse the simple science, Chris, but I picture what Elaine talked about in class that juvenile way.That is why the plants feed the bacteria. So when they are gobbled in a food fenzey, the corncobs (assiminable forms of n) will be where the plant can absorb them. I got a good grade in scissors and paste too! Like Leon says, KIS, Bob

chris reid <reidchris_at_earthlink.net> wrote:
Can you tell we had a snowstorm on the east coast? Lots more time to
compute.

Okay, back to Elaine's question on function of protozoa. Guess, what, I'm
assuming it's an open-book question, and got out my snowstorm reading
material (the Sylvia soil microbiology text). This is a good way to get the
info straight - give myself a reason to read that section. Oh, just checked
the author of the section to give them credit. Hmmm....says Elaine R.
Ingham. Good thing I decided to do that, huh?

Protozoa and nematodes both help recycle nutrients. The book says P and N
activities "such as predation of bacteria may provide between 25 and 75 per
cent of the nitrogen taken up by plants in agricultural systems...Along with
nitrogen, protozoa immobilize carbon, phosphorus, and other nutrients in
their biomass."

They also help inhibit development of disease-causing organisms in the soil.

The book says that "when no predators are present, bacteria and fungi retain
most of the nutrients in their biomass, reducing the nutrients available for
plant growth...When predators first colonize a soil, their grazing on B and
F increases the percentage of active biomass over ungrazed
populations...Therefore, the biomass of *active* B and F [author's emphasis]
may be greater when some predation occurs, even though total biomass might
be the same or greater when predator densities are low."

They also "assist in the dispersal of bacteria and fungi to new
microsites..." -- since bacteria don't have much ability to get around, the
P and N seem to be kind of like a Wolf's Taxi Service -- "I'll help you get
there if I don't eat you first..."

Chris Reid




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Received on Mon Dec 08 2003 - 02:02:40 EST

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