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Re: Species diversity
Hello to all,
Elaine Ingham wrote:
Plate counts are NOT APPROPRIATE for assessing numbers of species of
>bacteria or fungi in any soil, compost or compost tea. Plate counts >can
be useful for assessing numbers of individuals a few species that >we know
the conditions for their growth, but that's about it.
I agree with the first statement, however I hesitate to be as critical as
Elaine concerning the use of plate counts to evaluate the quality of compost
Even though plate counts only represent a tiny fraction of the biodiversity
in soil/compost, they may have good predictive value withrespect to the
disease suppression and plant growth promotion effects of compost teas.
Consider routine soil testing... the extraction/analysis methods used in
routine soil testing are not designed to measure the total quantities of
nutrients contained in soil... rather they measure relatively soluble pools
of soil nutrients that have experimentally been determined (through
extensive field testing) to be strongly predictive of crop response to
Do plate counts have value in predicting the functional value of compost
teas ? I have not seen the data but Joel Reiten seems to think so... I
expect that the Xanthamonas article he refered to in his recent post may
present evidence of the predictive value of plate counts.
Do microscopy methods have value in predicting the functional value of
compost teas ? I don't know... Perhaps Elaine can recommend an article which
reports a significant relationship between direct counts and the function
value of compost teas.
Dept of Soil Science
NC State University
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