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Aerating compost tea

Posted by grayentropy 5b (My Page) on
Tue, Apr 1, 08 at 0:07

I have an understanding of liquid gas diffusion and wonder if these compost tea aerating techniques I read about on the web are truely effective.The use of an aquarium (or shopvac!) air pump to provide aeration seems flawed as the bubble size is quite large and does not have sufficent time to dissolve in the water before dissapting into the air. In fact due to the relatively large bubble size, most aeration comes at the water/air interface. Air pumps are effective as they disturbe the surface and provide additional surface area for ambient air to diffuse into the water.

I question if the use of 5 gallon buckets with aerators actually provides better aeration than a wide shallow 55 gallon container filled with the same volume without aeration (increased surface area/volume at gas-liquid interface).

My theory is that a shallow container of compost tea (i.e 5 gallons of tea in one of those large rubbermaid storage containers ~35-55 gallons) would be better for brewing tea and may require no external aeration. I also suspect that attempts to brew tea during a good rain storm would be suficiently aerated by the rain perturbing the surface.

I will be using this method in the next couple of weeks but have no experience with compost tea to compare the results.

Does anyone have any thoughts to why a shallow tea brewed in a rain storm would not have sufficent oxygen to keep the microherd alive?

Follow-Up Postings:

RE: Aerating compost tea

Greyentropy asks:

"Does anyone have any thoughts to why a shallow tea brewed in a rain storm would not have sufficient oxygen to keep the micro herd alive?"

This topic has been discussed to the N-th degree all over the Internet. There are members on this forum that have stated a good stir with a stick every now and then is enough for good aeration; and then comes the shop-vac idea (with photos) that takes ideas to a different level. I do wonder what kind of fungal strand count survives after all that violent air time suspension after each explosion of air bubbles. My understanding is that one wants to dislodge the fungus from the compost gently to allow the strands to remain intact, but then I am still in the learning mode and may be getting taught something that I have not considered before. Time will tell on this one, for sure.

Your idea was kicked around about five (5) years ago on another forum that I know of. The final verdict was that no amount of air was going to be adequate to keep the biomass alive no matter how much air is infused into the tea. It was from that discussion that I came to the conclusion that larger air bubbles are good for the tea (for what that is worth) than smaller bubbles. As time has gone by many new discoveries have come to pass. IMO, the most important is the danger in using animal manure based compost used in tea making with molasses added could breed e-coli bacteria. Needless to say the flame from that fire is still hot.

Your idea of using a large (wider) container sounds like something I will try to see what happens. I will admit that my opinion is that biomass has nothing to do with the dynamic results of using compost tea. The link below will take you to the before mentioned thread, there may be something said that could be of use as you journey on this still exciting subject. I trust this may be of some help in some small way


Here is a link that might be useful: Compost Tea Brewers

RE: Aerating compost tea

I think a good microscope would settle the issue. Brew up a batch of both and see if you've got the same levels of microbial activity. I know of a guy who is observing tea after passing through a pressure impeller pump and sprayed ( at farily low psi) with no damage to fungi so it'd take a heckuva lot aeration to damage hyphae.

RE: Aerating compost tea

I've used everything from shards of glass to magnetic stirs to agitate portabella cultures grown in liquid mediums (a sterilized solution of karo syrup or honey in water) and it barely even shocks them. The more broken up the mycelium becomes the more rapidly it will grow.

There are a lot of parallels to mushroom farming and hot composting in terms of flipping the compost to redistribute the growth into new uncolonized substrate.

RE: Aerating compost tea

Does rain wash off the microherd from the leaf surface?
Or does heavy rain wash the microherd down past the roots to leach away?
In other words, should you NOT apply before a rain?

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