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

From: chris reid <reidchris_at_earthlink.net>
Date: Thu, 07 Aug 2003 13:01:02 -0400

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
in blended rose fertilizers(partial explanation), long drought in which
supplemental watering may not have been applied, soil drench may have been
used in the past for fungal control - knocked out mycorrhizae. This is an
established formal rose garden that has probably been here for quite a few
years, so the history could include nastier systemics. Well water used to
irrigate; haven't seen analysis of water yet (am curious about sulfur
levels).

If feeding and inoculation don't work, it will become critical to know the
reason why. But I'd like to anticipate potential sources of problems, and
think now about possible reasons why this has occurred/look into them so
that the trajectory of improvement of these plants is as rapid as possible.

Would welcome your experience in similar soil results.

Chris Reid


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Received on Thu Aug 07 2003 - 13:53:28 EDT

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