Re: [compost_tea] Soil app: sprayers

From: <soilfoodweb_at_aol.com>
Date: Sun, 3 Oct 2004 22:27:34 EDT

We have taken samples of tea before spraying through low pressure systems,
and through high pressure systems, adn then after the tea was sprayed thorugh
these systems.

We saw no reduction in bacterial or fungal activity or biomass when pressures
were as high as 1000 psi.

Examine the scientific literature, and note that in order to burst open
bacterial or fungal cells, pressure has to be quite high. As much as 1500 psi, and
preferably in the range of 3000 psi. French presses operate in that range.

The problem is NOT pressure. The problem is pumps that slice and dice
organisms with edges, and with impacts into flat surfaces at high speed. The
pressure does not kill the critters, it is impacting a hard flat surface when being
pushed along at high psi.

Think of yourself - being shot out of a cannon will not kill you. Impacting
a concrete wall 10 feet away after being shot out of the cannon will kill you.
 

Nozzles that rely on shooting water out at high pressure, straight into a
metal flange that forces the water to spray out in all directions can have some
life-ending impacts on organisms in that water.

But people can survive several gravities worth of pressure without any
problem. If the impact isn't too much of a shock, many organisms do survive being
smashed into those metal flanges, and getting sprayed out.

The ONLY way to know for certain the effect of any pump, sprayer nozzle, etc,
or passage through any equipment, is to test the tea before and test the tea
after passage thorugh the equipment.

Knowing activity is a very important aspect here. You cannot assess activity
using plate count methods. You cannot separate bacterial from fungal
activity using carbon dioixide evolution or respiration. You cannot separate
bacterial from fungal activity using enzyme methods. You cannot determine activity
be assessing DNA, or RNA.

No amount of theoretical anything is going to let you know for certain what
the effect of any equipment is on the organisms..

Please, TEST THE LIQUID BEFORE SPRAYING AND THEN IMMEDIATELY AFTER it comes
out of the sprayer. Or hose. Or tank. Or ...... whatever. Until you do the
testing, you will never know how much life you are lsoing as a result of the
equipment you using.

Judi, your microscope will help you to do this kind of testing, although you
cannot get immediate activity assessment. One way to assess activity changes
is to know the rate of increase (hour-to-hour testing) in the tea before you
pass it through the equipment, and then monitor the rate of increase after.

OK?

Elaine R. Ingham
Soil Foodweb Inc., Corvallis, Oregon
Soil Foodweb Inc., Port Jefferson, New York
Soil Foodweb Institute, Lismore Australia
Soil Foodweb Institute Cambridge, New Zealand
Soil Foodweb Inc., Oosterbeck, The Netherlands
Laboratorios de Soil Foodweb, Culiacan, Mexico
Soil Foodweb Inc., Jerome, Idaho
Soil Foodweb Inc., South Africa







Received on Mon Oct 04 2004 - 02:02:34 EDT

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