In recent years, Aerobically made compost tea has developed into a booming business producing Commercial compost tea makers that brew thousands of gallons of tea a day are available for purchase. There’s considerable enthusiasm about aerobically made compost tea with an increasing number of growers using it. There is a substantial amount of anecdotal evidence reporting its ability to restrain plant diseases and disease management of blueberries.

Aerobically made compost tea offers ecologically and economically sound answers to problems faced by farmers due to chemical build ups in fields and in ground water sources. While helping the farmer to overcome the chemicalization problems, other benefits include healthier plants, increased yield, less irrigation necessary, and more resistance to stress and drought conditions.

Aerated compost tea is great for acidic loving shrubs such as blueberry plants. Aerobically made compost tea should be the cornerstone of a fertilization program.


Aerobically made compost tea can help make healthy soil. Healthy soil in turn resists disease and insects and improves the mineral content. A new group of growers has started reporting remarkable results from using aerated compost teas to boost plant health and help control plant pathogens. In this age of chemicals much of the soil has lost much of its health. Farmers and gardeners have grown comfortable with the thought that we need to use pesticides, fungicides, weed killers, etc to successfully grow crops.

We think that if there is a bad pest or disease, we must get out there and kill it with pesticides. What we fail to realize, is that there is a huge amount of beneficial life that goes on in the soil and on the leaves. When we get out there to kill the disease, we kill off many of the beneficial organisms as well. What is not being considered is the long-term effect this has not only on the current crop and future yields but on problems of future such as pollution. Over time we kill off more and more of the beneficial microbes in the soil.

As a result there are not enough beneficial microbes (bacteria, fungi, protozoa and nematodes) left in the soil to do much good. But now with aerated compost tea we can replace chemical-based fertilizers, pesticides, and fungicides with badly needed beneficial microbes. Using compose tea your garden can now be safer and be more protective of the environment. The beneficial microbes in compost tea Increases plant growth and provides nutrients to plants and soil, Provides beneficial organisms It also helps to suppress diseases and replaces toxic garden chemicals.

These beneficial microbes perform many functions such as converting and releasing nitrogen into the soil. Using chemical fertilizers as time goes on; we find we need more and more nitrogen because the microbes are not producing as much. The microbes also hold nitrogen in the soil, but when they die off, the nitrogen as well as other nutrients such as calcium, are no longer held in the soil and leach away from where they contaminate ground water, rivers, lakes, etc. The pesticide chemicals are also leached away, contaminating our precious natural resources.

Brief History of Aerobic Compost Tea

At one time farmers made their own compost tea by placing a bag of compost in a container of water and letting it sit for a while. This compost tea was anaerobic and often smelly. Within the recent years, a new technology has developed replacing a container of stagnate water with a “brewer” that oxygenates the water. This produces live active microbes that are ready to go to work in the soil, which, if the soil is healthy, is also an aerobic environment. This process has proven to be very successful and is differentiated from the old fashioned tea by the fact that it is completely aerobic.

Compost Tea the Keystone of a Healthy Organic Fertilizing System

High quality, aerobic, compost tea is made from compost and other natural ingredients. The “brewer” extracts the beneficial microbes from these materials and food sources for the microbes in the compost to grow on is also added. These microbes will multiply many times over while the compost is brewing. Oxygen levels are maintained at a high level to make sure that these beneficial aerobic microbes reproduce and grow. These microbes when applied to the soil will repopulate the microbial population in the soil and on the leaves. These microbes do a variety of jobs in the soil including, Breaking down crop residues, unlocking nutrients as the plant needs them, Retaining nutrients, Reducing over-winter disease, Attacking disease organisms, Fixing nitrogen, Releasing soil nutrients especially Phosphorous, and Adding organic matter back into soil as they work.

On the leaves the microbes will occupy the space that could be taken over by pathogens and will form a physical barrier to the pathogens. It is, therefore, important to establish these good microbes ahead of any pathogenic invasion.

By adding these beneficial microbes back into the soil and onto the leaves, you are replenishing this invisible army that was lost by the use of harsh chemicals, so they can go to work for you. Less fertilizer will be required as these valuable microorganisms begin to repopulate the soil.

The Corvallis Oregon blueberry farmer (Bob Wilt) uses terms like biologically rich and nutrient dense and is happy to tell you how compost tea it has helped. Wilt said soil health has improved drastically for growing organic blueberries using compost tea as the foundation stone of his blueberry operation. A healthier, tastier product is the result with soil health improved drastically.

Compost tea formula.

Aerated compost tea is somewhat more complex than non aerated compost tea, and involves supplying oxygen using a mechanical air pump (such as an aquarium air pump) to the microbial population in the compost solution. Several compost tea brewers are now available commercially; you can also build your own.

A fairly typical recipe for aerated compost tea is based on vermicompost, with soluble kelp, humic acid, and ground up fish carcasses (i.e. fish hydrolysate) as added nutrients and a small amount of peanut oil to reduce foaming.

The conditions necessary in tea production are:
1. Water at room temperature
2. no chlorine in the water (aerate to de-gas) if it is chlorinate let it set over night
3. neutral water (pH 6.5 to 7.5),
4. oxygen maintained above 6 ppm through the entire brewing cycle, and
5. Good aerobic compost.

Compost tea recipe currently used by some

100 gal. Of de-chlorinated water (allow water to sit or aerate over night) use natural well water if available.
30 lbs. of quality compost or vermin-compost (worm castings); the quality of compost directly relates to the quality of tea
32 oz. organic molasses or pre-blended nutrient mix (Sustainable Agricultural Technologies)
16 oz. soluble cold-water kelp meal
Optional: Finely crushed shells of one to two dozen eggs can be added into the fertilizer teas as you make it.

Note: the molasses is added near the end of making the compost tea but while the tea is still being aerated. The molasses provides sugars for the micro organisms in the tea to eat and multiply.

A different level of microbial population will be produced in your tea based on weather, temperature, seasons, etc. In the summertime when it is warm you can expect your teas to brew faster and obtain the most favorable microbial levels sooner than in fall weather when it is cooler.

Swearing by kelp

Practically all organic farmers in the know swear by including kelp as a vital component in the making of compost teas. Nearly all of the kelp extracts used in agriculture comes from the common North Atlantic kelp species Ascophyllum nodosum. Kelp contains some 60 naturally occurring major and micro nutrients, carbohydrates, and 18 amino acids, vitamins and naturally occurring growth promoting substances.

Biological Factors

Over the years farmers are finding they have to use more and more fertilizer to keep up with their crops. A major reason for this is the fact that the beneficial microbes gradually get killed off in the process of intensive farming due to pesticide use, soil compaction, extensive tilling, etc. If these microbes are not replaced, nutrients will no longer remain held in the soil and will leach away into the ground water. By replenishing theses microbe with good quality aerobic compost tea, you are putting the biology back into the soil that will hold nutrients and greatly reduce or eliminate leaching.

The beneficial microbes in the soil are also natural predators against disease organisms. When these beneficial microbes are not present in sufficient numbers, the disease organisms multiply in abundance causing more need for chemicals. The beneficial microbes in the soil take time to multiply and grow, so applications are best done the previous fall for a crop this spring, although spring applications are still beneficial if none were done last fall. Many diseases over winter in the soil and the microbes need time to find food, multiply, and start their work.

These microbes need food. Applying the microbes without any food to grow on, will have limited benefit, if applied to the leaves, you need to spray the tea on with an activator or microbial food, so the microbes can get started. An active bacterium secretes a sticky substance that will stick it to the leaf. After the microbes have established on the leaf, they will feed on exudates from the leaf and the leaves will feed on the exudates from the microbes. Aerobic compost tea is not a fertilizer per say but it is a part of the whole fertilizing picture. It contains the biological life that will significantly increase the benefits of the nutrients already in the soil, but it is still important that the nutrients be well-managed and balanced. Failure to do so will decrease the benefits obtained by the tea.

Applying Compost Tea

While aerobic compost tea applications have many benefits to the grower, the tea must be applied keeping biological laws in mind in order to ensure that the treatments are successful. Compost tea is a biologically active liquid concentrate of living organisms that is very perishable. It should be used as soon as possible after making. The millions of live microorganisms in the tea use up available oxygen very quickly (within 4 -6 hours of brewing) if it is not being oxygenated by pumping air through the tea the microorganisms will die. Aerobic compost tea is a liquid containing a rich diversity of living bacteria, fungi, protozoa, and more that are ready to go to work, but they must be given what they need to live and multiply.

There are certain principles that must be kept in mind during application. Oxygen levels must be kept up until application, but this is quite easy using simple fish/aquarium equipment. There is some particulate matter in the tea, so larger filters (>25 mesh) and therefore larger nozzles are necessary. A diaphragm pump is recommended if possible.

Aerobic compost tea must be applied in the cool of the morning or the evening so the microbes get a chance to establish before the sun is too bright. On the leaves, it is important to apply at least 6 hours before a rain so they are not washed off before they can stick on. If doing a soil application, during or just before a light rain would be ideal.

The usually rate at which compost tea is applied is at the rate of 5 gallons per acre and at a temperature of about 65 to 70 degrees Use well water if possible not chlorinated water.

How Often To Apply

As a soil soak, at least 2-3 applications are recommended during each growing season. Applications on the leaves should be made every 10 days during periods of high disease pressure because the micro organisms do not live long on the leaf surface…

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