Re: [compost_tea] Re: Getting Oxygen into Tea and Preserving Fungi At The Same Time

From: <soilfoodweb_at_aol.com>
Date: Sat, 01 Nov 2003 13:09:38 -0500

Ah, we aren't talking mammlian respiration systems in compost tea. As far as I know, we aren't trying to send divers to live in the bottom of the compost tea machine.

Could we stick trying to understand microbial respiration?

The thing of concern is transfer of oxygen into the water. Oxygen is being used up in the water so rapidly by the microbes that oxygen concentration is dropping to below 5.5 to 6 ppm.

Unless I am mis-remembering my courses on microbial respiration, high concentrations of N2 gas don't really affect microbes much until you get to above 85% N2 in the atmosphere.

N2 gas is at 75% in the total atmosphere, so you have to pressurize air bubbles a great deal more than we are, even with 20 foot deep, or 200 foot deep, tanks, to cause a problem for the microbes.

It is the use of oxygen by the microbes, and then diffusion of oxygen from bubbles into the water that is the important balance. Since we are depleting oxygen in the water, the movement of oxygen from the bubble into the water will be more dependent on the diffusion co-efficient based on the gradient between oxygen concentration in the water versus the air bubble.

The more rapid the growth of the microbes, the more rapid the diffusion of oxygen from the bubble into the water. The whole concern about the maximum movement of oxygen from the bubble into the water requiring at least 3 or 4 feet depth of water just went out the window.

I think many of you still are hung up on the fact that you just can't believe that bacteria and fungi can be growing so fast that they can use up 3 CFM of air being bubbled into water fast enough that the water can still be dropping in oxygen content.

But they do. It's what your oxygen probes are telling you.

So, what do you do to solve the problem? Bigger and bigger pumps?

Hum, the engineering approach to life. Get a bigger hammer. Doesn't work with living systems. Bigger hammer? Bigger problems......

How about considering LESS FOOD?! MATURE compost?!

Comprende?

Elaine Ingham
President, Soil Foodweb Inc.
SFI Corvallis, OR
SFI Port Jefferson, NY
SFI Lismore, NSW, Australia
SFI Hilversum, The Netherlands
SFI Cambridge, New Zealand
www.soilfoodweb.com

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Received on Sat Nov 01 2003 - 13:47:00 EST

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