Sunday, March 29, 2009

Making Your Own Compost Tea

Compost Tea.  One of the hottest topics in natural gardening is actively aeriated compost tea (AACT).   This is different from the more passive leaching compost tea because you are applying air (oxygen source) and food (molasses) to the water and compost to quickly grow beneficial microbial life.  By taking good compost, full of beneficial microbial life, and putting it in a bucket of water aeriated with plent of oxygen and a food source, you can produce a living, liquid soil and plant additive that can enhance your soil health, increase plant health, yields, and beauty, and limit/prevent disease, pest, and drought damage.  And you can make it yourself for very little money.  I'll get into the science behind it in later blogs, but for now, here's the quick skinny for getting started.  Also, look in the Natural Gardening Links section for links to videos from Bob Webster and Bruce Dueley, both Texans, on compost tea making.

Building A Compost Tea Brewer.  A brewer is very easy and cheap to build.  You need a container, preferably plastic (metals can harm the microbes), an air pump, plastic tubing, air stone(s), and a tea bag large enough to hold 5 lbs. of compost.  The system you see in the picture is 25 gallons and cost less than $30.  The tub was purchased at the Dollar Store and the rest came from Walmart.  The "tea bag" is a pillowcase but I've heard that paint sprayer bags are also quite good and inexpensive.  

Set Up.  Set up your brewer on level ground in the shade with electricity nearby.  You will need electricity for the air pump so site it near an outlet.  The brewer works best in the shade as UV rays can destroy the microbes.  Finally, place it close to where you will be using it most.  It's no fun carrying it a long distance!  Hook up the air pump to the air stones using the plastic tubing.  Place the air stones on the bottom - use duct tape if they will not stay.  The pump does not go into the water!

Fill tub with clean, non-chlorinated water - rain water is best.  If you only have city water, run the air pump for several hours to remove the chorine.  When your water is ready, put your compost tea recipe into your tea bag and place in the brewer.  The bag should be secured above the bottom.  You can tie the bag to the handles or place something like a small basket in the bottom to suspend the bag.

Recipes.  Compost tea requires two ingredients:  a biological source and food for the biology.  If this is your first time brewing compost tea, I recommend starting with this simple recipe: 5 lbs. of good compost and 1 oz. of molasses.  Once you've got some success, begin adding ingredients.

Brewing Instructions.  Once your brewer is set and the tea in place, turn on your air pump and you are brewing!  It typically takes 24 hours to build a good colony of microbes.  I know people who run theirs up to 72 hours.  You can probably run it longer but you would have to mange the food/oxygen supply which could get tricky.  I will write later on some of the more complex recipes and additives that you might want to try.

How Do You Know It's Working?  Smell it!  We are designed to differentiate between beneficial and pathological microbes.  Good soil smells good.  Rotton food smells bad.  Use your nose.

Good compost tea will smell slightly sweet.  As you start running out of sugar (molasses) in the tea, the smell will become yeasty.  If it smells bad, pour it out (not on your valuable plants) and start over.

Clean-Up.  Bacteria produce slime (biofilm).  This must be cleaned up after each use.  Usually just rinsing with water will suffice but you may want to use some vinegar or mild clorox dilution.  Let it dry in the sun and it will be ready for use.

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