Tuesday, October 13, 2020

Compost Tea - With and Without Aerator

We're brewing compost tea, partly to go with our biochar.  We wanted to find out whether it's effective to aerate the tea by simply stirring it every day, so we started two batches of tea in 5 gallon buckets - one with a pump aerator and one without.

Why does aeration matter?  In theory, the beneficial microbes we want to cultivate in our tea are aerobic (oxygen-loving), whereas anaerobic (not oxygen-loving) microbes that would grow in the absence of oxygen tend to be parasitic or pathogenic to plants (and people).  Our pump aerator consists of an aquarium air pump connected to a loop of 1/4" soaker tubing, which you can see in operation in the image below.


The ingredients we used are:

- 4 gal dechlorinated water

- 6.5 oz compost

- 1 Tbsp kelp juice

- 1 Tbsp molasses

Normally we wouldn't have to measure this precisely, but in this case we wanted to make sure the only difference between the two batches was the presence or absence of the pump aerator.

Then we let the tea sit for three days, stirring one bucket every day and leaving the air pump on constantly in the other.  After three days, we got out the microscope and captured the videos below.

Aerated by stirring:

Aerated by pump:


The differences between the two buckets, in terms of quantity of individuals and species, were so dramatic I felt compelled to check three different slides from each bucket to confirm.
The pump-aerated batch was filled with cocci.  I don't know enough to identify the species, but it stands to reason they are aerobic and beneficial.
The stirred batch was filled with protozoa.  I also observed two shapes of bacteria: cocci and bacilli.  Again, I don't know enough to identify the species, but they're most likely anaerobic.
From now on, we'll be brewing all our compost tea with a pump aerator.

No comments:

Post a Comment