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Compost Tea
What is compost tea? As it is with many things, it is many things to many
different people. What do you think compost tea is?
Not all compost tea is equal.
Way back in the "good ol' days" before electricity and the invent of chemical
fertilizers and pesticides, the gardener/farmer had natural ways to coax the
most they could get from the land. Back then they'd throw a heap of manure
in a bucket, add water and let it sit for a spell (usually 7 to 14 days) until the water was a nice
dark "tea" color. Over the years the art of composting was developed and
instead of using manure, the finished compost was used to make a tea which, in
both cases, was used as a liquid fertilizer. The by-product of this method
would officially be called "Compost Extract".
Take a leap forward to present day. Soil health has become a science
and along with that has been the development of the science of vermicomposting
and the bacteria or fungal rich tea that can be produced from the finished
product. But in order to do that requires more than dumping some
vermicompost in a bucket and letting it sit. Likewise, the "compost leachate" that
is the dark solution obtained from the bottom of a worm bin or compost pile is not even close to the same thing as high quality
compost tea or AACT ( Actively Aerated Compost Tea) that the experts are
referring to when they speak of Compost Tea. Compost tea, in modern
terminology, is a compost extract brewed with a microbial food source —
molasses, kelp, rock dust, humic-fulvic acids are common ingredients. The
compost tea brewing technique is an aerobic process that extracts and
grows populations of beneficial microorganisms.
The experts will tell you the most valuable compost tea is one that has been
brewed with an aerator and some sort of food source for bacteria. Because
that is what you should be growing when you brew compost tea. The
bacteria is what makes REAL COMPOST TEA a great value to the grower.
There are actually not a lot of nutrients in compost.
Nutrients are rather possessed and released by the microorganisms
and their activities in the soil at the root level.
There are some nutrients in compost and trace minerals and some of
these would most likely be discharged into the water through the
brewing action. However the brewing action and aeration is primarily
intended to break away microbes and multiply them to boost the
nutrient cycle at the soil/root interface. There should not be the
impression that nutrients which are available to the soil/plants are
being extracted from the compost, especially considering the mindset
of nutrients from the chemical fertilizer arena.Whenever compost has
been tested for NPK it always has come in very low. On the other
hand tests of manure and other raw materials prior to being
composted test much higher. Once the composting is completed the
nutrients are available to and through the microbes?
This is a relatively new field and there are many differing opinions, but
there are a few facts that are hard to dispute:
- Good compost is an absolute necessity - If you are going to brew
a high-quality compost tea then you have to start with a high-quality
compost. You can only grow whatever you have present in your compost.
Therefore, if you are a professional grower, or if you are battling a
particular problem you will want to know exactly what your have in your
compost and you will want to have it tested. But if you are just a
gardener trying to improve on the health and productivity of your families
crops then if you build a healthy compost with a variety of materials
that should suffice.
- A food source is essential - In order for your micro-organisms to
grow in sufficient numbers there must be a food source. The goal is to
provide enough food to maximize your growth of beneficial organisms without
over-producing and causing the tea to go anaerobic because the organisms use
up all the available oxygen.
- Oxygen - All living organisms need oxygen to live! The
organisms in your compost tea are no different. If there isn't enough oxygen
while you are brewing you will start growing anaerobic pathogens which are
toxic to plants. By keeping the oxygen levels high you are growing the
good biology, which is what you want for your plants.
Not treated with
compost tea. |
Treated with
compost tea. |
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Client Corner
In the spring of 2004, Gus Wahner sprayed 1/2 of this cherry
tree with compost tea. He used a mixture of 4-gallons of compost tea and
1 c. of fish emulsions. These are the results after only one spraying!
This is a great example of beneficial microbes increasing nutrient
cycling. At harvest time, you can see the difference. Yields were higher
and leaf mass and health was also better on the sprayed side. In fact,
much of the fruit is actually obscured from view by all the foliage on
the compost tea side!
Gus runs Custom Composting Services in Hermiston, Oregon. He has been
using compost tea for 3 years. Gus has been a proponent of organic
practices and compost tea fits nicely into his program. You can contact
Gus at gusatbiotea@aol.com or by phone at (541) 571-2300 for more
information about his company or programs. |
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