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Gardening – Compost Tea

What is compost tea?

Setting up compost tea home brewer. Compost tea is an aerobic water solution that has extracted the microbe population from compost along with the nutrients. In simple terms, it is a concentrated liquid created by a process to increase the numbers of beneficial organisms as an organic approach to plant and soil care.

You can use any kind of compost, but those that are well aged have the most nutrients. Vermicompost, which is made from worm castings, is probably the best you can find. The worms do the work in a very short time, often cutting years off the normal schedule. Compost normally takes 3-4 years to fully break down. This is, if it’s done naturally. If you use a machine, or a roller, compost will decompose more quickly due to retained heat and moisture. Whatever kind of compost you use, be sure it has no chemicals that may harm your plants.

Setting up a home brewer.

a five gallon bucket
compost
an old pillowcase or nylon stocking
string to tie the pillowcase/nylon stocking
a few tablespoons of molasses
an aquarium pump
a length of air hose long enough to go from the pump to the air stone
an air stone for an aquarium
water

Instructions:

Pretreat your compost to increase its inoculant and fungal power. Take your compost inoculant and add some humic acid or fish emulsion to it. Put it into a shallow tray and mix it up well. Then let it sit for two to three days. This encourages fresh microorganism growth in the tea. You can treat this as an optional step or you can see it as a way to increase the effectiveness of your brew.

Comparison of plant roots grown with or without compost tea Fill a bucket with non - chlorinated water. The water temperature is ideally between 55-80oF. If using tap water, leave it sitting and uncovered for 24 hours to off-gas any chlorine, or add humic acid to it to deal with chloramine.

Put the pump air stone (from an aquarium store) in the bottom of the bucket, attach the air pump and let it start to bubble. Make sure there is enough oxygen and agitation moving through your liquid. Remember, you are looking for more of a churning or rolling boil, not simply fine bubbles.

Put compost in the panty hose stocking or mesh bag, tie off the end and suspend it in the water.

If you want to increase the diversity of your compost tea, we suggest adding a cup or two of garden soil. Better yet, if your compost tea recipe calls for fungal compost, include a cup or two of soil from a nearby forest. By adding these additional soils, you're ensuring your tea is inoculated with a wide range of soil microbes. These soils are like a biological catalyst, or compost tea activator.

Add the food.

Let the whole brew bubble for 12 hours and for no longer than 18 hours. After 18 hours, if the tea received insufficient oxygen or too much food, anaerobic organisms will overcome the beneficial aerobic organisms. It will be obvious if the tea went anaerobic, because it will stink!

As you might guess, there are many other alternatives in creating compost tea and the recipes vary in fostering the differential growth of bacterial and fungi.

Bacterial-Dominated Compost Tea Recipe

1.5 pounds of bacterial-dominated compost (vermicastings works well)
2 ounces of cane sugar
1 ounce of soluble kelp

Bacteria love simple sugars, so feel free to add in a teaspoon of maple syrup, or even white sugar.

Fungal-Dominated Compost Tea Recipe

2 pounds of fungal-dominated compost (see tips at bottom of page)
2 ounces humic acids
2 teaspoons of yucca extract
1 ounce of liquid kelp
2 tablespoons of ground oatmeal

Balanced Compost Tea Recipe

1.5 pounds of balanced compost (equal parts bacterial to fungal biomass)
1.6 ounces of humic acids
2 teaspoons of yucca extract
1 ounce of liquid kelp
1.6 ounces of humic acids

Add yucca extract near the end of the brewing process, since it has a tendency to create a lot of foam. Also, you'll want to make sure your yucca doesn't have any preservatives

Common Compost Tea Recipe Ingredients

Ingredient Feeds Ingredient Feeds
White Sugar Bacteria Maple Syrup Bacteria
Corn Syrup Bacteria Cane Sugar Bacteria
Molasses Bacteria/Fungi Fish Emulsion Bacteria
Fruit Pulp Bacteria/Fungi Fish Hydrolysate Fungi
Kelp Bacteria/Fungi Ground Oatmeal Fungi
Rock Dusts Bacteria/Fungi Yucca Fungi
Humic Acids Bacteria/Fungi Soybean Meal Fungi

Tips To Improve Results

Tip 1. If you want to increase the diversity of your compost tea, we suggest adding a cup or two of garden soil. Better yet, if your compost tea recipe calls for fungal compost, include a cup or two of soil from a nearby forest.

Chart showing why you should use compost tea. By adding these additional soils, you're ensuring your tea is inoculated with a wide range of soil microbes. These soils are like a biological catalyst, or compost tea activator.

Tip 2. Don't accidentally filter out your fungi (and nematodes) when straining your tea. When filtering your tea, be sure your screen is as close to 400 micrometers as possible. Paint strainers, from your l ocal hardware store, work quite well for this function. Avoid using socks or pillowcases, since their fibers are too tight.

Tip 3. When we want to ensure we've got fungi in our tea, we will brew it, and then add spores of mycorrhizal fungi. Mycorrhizal fungi act as a wonderful inoculum to any fungal compost tea recipe. These fungi naturally form beneficial relationships with approximately 95% of all plant species. They aid in nutrient transfer to plants, and help to create better soil conditions

Tip 4. There are commercial setups for brewing compost tea that make it easier to get started including pre-packaged compost and food for the bacteria and fungi

Further Information

Introduction to Composting
6 Ways to Make Great Compost
How To Choose a Compost Bin
EPA: Types of Composting & Understanding the Process
How To Make Compost Tea