[compost_tea] function of protozoa

From: chris reid <reidchris_at_earthlink.net>
Date: Sun, 07 Dec 2003 22:53:17 -0500

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 Sun Dec 07 2003 - 23:25:45 EST

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