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What kind of organisms are we trying to create when brewing compost tea? Is there a certain type of species? Or are we just trying to get a wide variety of microbes?

I ask these questions because as a microbiologist I know different types of bacteria incubate at completely different temperatures. Depending on what types of organisms we are trying to grow in our tea we can increase the effectiveness. If we kept the tea at the correct temp consistently we could vastly increase the amount of beneficial organisms in our tea.

This idea has probably already been brought up and discussed so I am sorry if this is a repeat thread. But any discussion or information would be awesome!

4/13/2013 9:19:26 PM

Seattle, WA

There's 2 theories of thought on this:

1. Brew at ambient temp to select for organisms most adapted to the particular temp at which they will be applied.

2. Brew at optimal temps (approx. 70F)for microbial growth.

I subscribe to the 2nd theory, because ACT really is a "shotgun" effect. We're just trying to get as many beneficial organisms back into the soil and letting the plant sort it out. Plus, these soil based organisms are highly adaptive and can survive huge temperature swings throughout a given year (just look at how much your soil temps can vary). Any organisms that aren't adapted to the given temps will just become food resources for other organisms or go dormant until conditions for them become right.

I haven't seen any good research regarding differences in brewing temps, but that's always been my logic on the subject, and what I tell my customers.

4/15/2013 1:29:23 PM

Thanks for the response!

Brewing at the same temp as your soil is a good thought and what I will probably end up doing.

There is probably a very fine line between maximum growth and brewing poison. For instance a organism such as B. Subtilis (which some of us apply as a fungicide) grows optimally at around 85-95 degrees. Where as brewing temps above 90 degrees could cause lack of O2 and grow harmful organisms.

I think I will let nature take its course and let the tea brew at whatever the environment provides.

4/15/2013 9:21:26 PM

Seattle, WA

Keep in mind that I'm assuming that you're maintaining appropriate dissolved oxygen levels and not adding too much nutrients to the brew when brewing at optimal temps. I totally get what you're saying though, and recommend cutting back on "foods" in teas when brewing at higher temps.

4/16/2013 4:46:20 PM