[compost_tea] Re: high active bacteria, low total bacteria, low active and total fungi - possible reasons?

From: growest2002 <g.w.thomson_at_shaw.ca>
Date: Fri, 08 Aug 2003 15:01:41 -0000

Chris-with my amateurish amount of experience working with
mycorrhizae
in ornamental nursery plants, I'd say a good bit of the problem might
be a history of "inorganic" fertilizer application.

Mycos are very sensitive to free phosphate (which is apparently very
rare in soil under "natural" conditions). Myco innoculant
manufacturers all recommend using NPK ferts with a low middle number,
always under 10, or applying reduced rates. With both high nitrate
and phosphate levels in the soil test, I wonder if any myco has
persisted on the roots of your roses. As an aside, I doubt that the
SFI active/total fungi numbers reflect myco, altho they point to a
non
fungi-friendly soil. I believe a separate root analysis is needed to
determine how much colonization of myco is there.

With high levels of nutrients in your soil, I imagine that adding
organic matter will be all that's needed in the future...my 2 cents!

Glen

--- In compost_tea_at_yahoogroups.com, chris reid <reidchris_at_e...> wrote:
> On a recent soil test, the results showed a mid-range total
bacterial
> biomass, and of that high active bacterial biomass (137.7, where a
range of
> 5-15 is desired range). Total fungal biomass is low (139, with
desired
> range 200 - 300), and active fungal biomass is at 16 of 139.
>
> Does anybody have suggested causes of this big difference? Soil
tests show
> 5.1 pH, high available nitrate nitrogen, low available ammonium,
high to
> very high phosphorus, very high potassium, very high calcium,
medium
high
> magnesium. "Crop" is hybrid tea roses (formal rose garden). It is
next to
> a lawn and a boxwood hedge, but the area is level and based on the
pH, I
> don't think the roses are getting lawn runoff (especially since
they've been
> liming the lawns indiscriminately for years...).
>
> PHC on their website has a chart of the effect of various
fungicides
on
> mycorrhizae. I'm told that the two most common ones used on roses
would be
> Maneb and Mancozeb. They are not supposed to do much harm to the
> mycorrhizae.
>
> So, the scenarios that occur to me are: excess triple super
phosphate used



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Received on Fri Aug 08 2003 - 12:25:17 EDT

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