Philosophy of Compost Tea and Extract

As Da Vinci once said, “Water is the driving force of all Nature”.  This too is true within soil and our ability to use this universal solvent to propagate microbes on an unfathomable microscopic level is a powerful regeneration tool. It’s a tool that greatly aids in healing years or centuries of land abuse and switch the paradigm of chemical resources to the use of biological resources.  Thus having appropriate quantities of humidity in the soil allows microbes to flourish and keeps nutrient cycling speeding along as photosynthesis comes to a grinding halt in the summer in places like the Mediterranean dry season.428861_380145602039048_229211388_n This links directly to plant health and transitions into human and animal health as well as overall ecosystem health and local climate extremes. As soil builds, as systems become more biodiverse and complex, soils build in organic matter percentage and are able to hold and infiltrate more moisture. This allows for increased plant growth and their photosynthetic process which symbiotically promotes even more microbes. This interweaving link of plants, water, animals, and soil is inextricable and our species depends on this web of life.  Fortunately this can be leveraged with modern technology like compost tea and extract and its fusion force between soil and water. In this technique water becomes the medium for delivering a diverse and complex soil food web to regenerate ecosystems. This technique of soil re-innoculation is an embodiment of the Permaculture principles labeled as accelerating succession and evolution and diversity. Several techniques can be used to proliferate microbes and spread them on varying scale from broad acre to small-scale intensive systems. Use of teas and extracts of compost speeds the healing process along and can be incorporated in earthworks strategies, tree planting, garden installations, and fertility maintenance. Compost tea is a word thrown out meaning varying things but this article is meant to dispel some of the myths and give you an easier version of it known as compost extract when contextually appropriate.

General Pattern

soil food web- credit soil symbiotics

soil food web- credit soil symbiotics


5 gallon compost tea brewing

Compost teas and extracts involve dispersing finished compost composed of a diverse and complex soil food web of beneficial microbes into a water solution. There is often a focus on fungal rich brews as we often lack this basic building block in our present state of soils. Ideally, and when done commercially, monitoring of this microbial life is done with a microscope. Brewing size can be from 5 gallons (20 L) up to 1000 gallons (4000 L) or more depending on the scale of brewing equipment and subsequent distribution equipment. To facilitate this, a brewing process is needed to separate the microbes from the compost allowing them to be suspended in the water solution. Distribution materials range from hand systems with a bucket and a wand of willow all the way up to the same equipment and technology associated with industrial agriculture. This is something that can be done individually on the farm or like in my time in New Zealand (2006-2007) sometimes this service is available commercially. A simple phone call contracted the service and this business is a green job opportunity as we desperately need these alternatives to conventional chemical fertilizing and pest and disease control.

Teas vs. Extracts

Compost tea differs from compost extract in little way except a few factors including the brewing process. The decision on which one you use depends on your end purpose of it and starting material. Compost

Earthfort's Fish Hydrolysate

Earthfort’s Fish Hydrolysate

tea potentializes a small amount of compost through a longer brew time, mechanical aeration inputs, and addition of microbe food such as kelp or fish hydrolysate. Compost extract is made with a larger volume of compost and a shortened brew time. The end use differs in that if you want to coat the leaves of plants with this soil food web to prevent disease, you need to activate it through the compost tea brewing process. Then the solution will stick to the leaves through the active aeration process.  If you are merely doing a soil drench to repopulate and feed microbes, compost extract is sufficient and much easier to do than a tea.

Compost Tea

Often referred to as actively aerated compost tea, this specific term and technique was developed by Dr. Elaine Ingham, a true pioneer in this great frontier of soil science. I have had the pleasure of studying and assisting Elaine in courses and consider her one of the great heroes of the modern age in regards to switching the industrial agriculture paradigm. Her microbial research led her to a dynamic soil rehabilitator that became known as compost tea, but I

Dr. Elaine Ingham

Dr. Elaine Ingham

have heard the word used loosely in many regards. Plant fermentations such as comfrey and nettle can be wonderful soil contributors but should not be referred to as compost tea. Compost is the building block of the recipe and special attention to building hot compost piles correctly is needed to ensure the good guy microbes are there and the bad guys are not so present or better yet devoid entirely. Additionally vermicompost can be used but often when making teas we are looking for higher counts of fungal counts which hot compost piles facilitate quite well. Growing more fungus is also possible with any type of compost by adding a small handful of steel cut oats to the compost weeks before a brew is to ensue.  Additionally fish hydrolysate will do this as well.

The following is the basic equipment and ingredients needed:

  • A bucket or tank of varying size to hold the water and facilitate aeration
  • An air pump and its distribution system for aeration (hoses)
  • A tea bag (fine mesh or synthetic or natural material that holds the compost)
  • Well made, finished compost and hopefully monitored under a microscope
  • Foods for microbes (Fish hydrolysate, Kelp)
  • compost tea schematic- image credit

    compost tea schematic- image credit


Once you have selected your brew size and the tank to hold it, compost is procured that hopefully has been monitored by a microscope ensuring the full range of microbes is present. It is then put in the compost tea bag and fitted to the bucket so it is suspended at the top of the water column but completely submerged. Often a dowel rod helps with this as it sits on top of the tank and then the bag is hanging downward from it. Furthermore, the air pump tube needs to be put into the bottom of the tank and be powerful enough for vigorous bubbling to occur. This ensures plentiful oxygen quantity and separation of the organisms from the compost as the microbes, just as in a hot compost, demand lots of oxygen. The pump rests on a table or fixture above the tank and the tubing is often fixed in a circle at the bottom to create a plentiful aeration process. A reliable oxygen input is needed so often this involves plugging into the grid as most off the grid systems will not support this energy demand of an air pump. A medium water temperature is asked for so supplemental heating may need to occur in winter time for the brew.

Fungi- photo credit Rodale institute

Fungi- photo credit Rodale institute

As the brew is occurring, foods are added to stimulate certain organisms in the tea. As the science of compost tea has developed, the research of Dr. Ingham and others has dictated that molasses is no longer needed in these particular brews. This simple sugar feeds bacterial populations but often enough the bacteria flourishes regardless. In general, again, we are after more fungal rich teas as well as the other higher organisms in the food web such as nematodes and protozoa. We need other foods besides just molasses to spur their growth hence the present day exclusion of this food source. Thus the following recipe from Zach Tabor and the Cincinnati Permaculture Guild shows this and can be scaled up or down.

 Compost tea recipe Compost tea recipe

Compost Extracts:

Compost extracts are easily made and can even be brought forth with no mechanical intervention. This is important for off-the-grid folks who may not be able to support an extended brew time that compost tea demands. Basically it’s the same set up of a compost tea bag put into solution which was described above.  However sometimes an old t-shirt serves as my compost holding bag as roots-style preparation is very possible with extract.

hot compost pile turning- a process to build the raw ingredient

hot compost pile turning- a process to build the raw ingredient

Bubbling can be used to separate the microbes from the compost or a simple massaging technique.  If massaging by hand to separate the microbes from the compost (the function of aeration in both), I recommend the biodynamic stir after massaging the bag for 3-5 minutes.  This particular stir bring things more alive through bringing the vortex pattern into the water body.  To do so, you stir with a stick or hand in one direction for a while bring a vortex or order into fruition.  Then you switch directions causing chaos to ensue but quickly the vortex forms again.  Quite often the water is sluggish at first and has trouble forming a vortex but waters’ memory is quite profound and its gets easier pretty quickly.  You keep alternating directions for this three to five minutes total time.  Either way the microbes become suspended in the water and appreciate this shortened form of brewing as there is no need for activation as the end products simply goes to the soil.  No extra ingredients are added and bubbler brew times can be short and last up to three hours if you do choose to aerate it.  The resulting product is full of microbes and just as dense as teas as you use a bigger dose of compost in the bag to compensate for the lessened brew time and lack of further foods. Recipe again from Zach Tabor based off of Dr Ingham’s ongoing research.

Compost extract recipe

Again if you want to do a soil drench, compost extract is a great resource but if looking to also coat leaves a compost tea that is actively aerated is the choice. Also if you only have a small amount of compost and large area to spray, then compost tea helps to exponentially increase the microbes thus resulting in a smaller amount of compost used.


Making compost more fungal before brewing or extracting

As to make compost more fungal I have tried a few different things.  First is to remove compost from a pile or bin and place it in a cardboard box.  From there I add less than a handful of steel cut oats to this medium-sized cardboard box.  I mix it in and wait.  I also have had other plastic containers with mycelium rich wood chips or leaves and add a bit of that in slowly.  They are all like science experiments and these little fungal ecosystems help. I mix in the wood chips or lay them on top and put leaves over them.  I monitor the humidity levels and water with rainwater to keep the humidity appropriate for fungal growth.  Sometimes I will do this for months but the handful of steel cut oats at the very least two weeks before brewing will definitely support the fungal counts. And don’t overdo it, a little bit goes along way and give ten days between feedings. Its better to use a small amount of oats and do it frequently than just dump a bunch in as it will go rancid and breed pathogens.


When brewing teas and extracts and their subsequent application, there are several factors to consider.  First is the water itself since it is the carrying agent of the life of microbes.  Use of stream, roof catchment, pond, well, or spring water is recommended.  Use of city water is not recommended as chlorine and chloramine are added to kill life.  At one time it was enough to let the volatile chlorine off-gas for 24 hours but now the much more stable and potent chloramine is added.  The only way to neutralize this is through adding humic acids.  These can be added from commercial sources or simply extracted through pouring water over a bag of compost.  The leachate should not be watered down so that the eventual color of the water is that of chocolate-brown; in fact a 70% chocolate bar color which is of course quite rich.

Once a brew or extraction is complete, its timely application is something to be considered stringently.  First it should be used relatively immediately but within 24 hours as it can go anaerobic quite quickly and then be a waste of resources or you end up spraying the microbes out that you don’t want to be present. For application, the simplest hand methods of say a 5 gallon (20 L) brew is merely distributed by dunking a bundle of branches or leaves into the bucket and flinging it outwardly.  It comes out in a spiral fashion and quite beautiful and meditative.  Often backpack sprayers are used and in commercial application equipment that is normally used for pesticide spraying can be utilized.  New equipment or those that are well cleaned from these substances are advised.  An important thing to consider with application is the size of the nozzle for application.  If too small the application will kill the microbes as they are forced out under pressure.  To alleviate that always use a 200 micrometers in width nozzle.  Thus you may need to retrofit those on past spraying elements.

backpack sprayer with boom, can be used for microbes instead of chemicals

backpack sprayer with boom, can be used for microbes instead of chemicals

Also a thorough cleaning of all the equipment must be done after each brew and design this into your work schedule and how you put the system together.  If not biofilms build and teas and extracts can be completely ruined in the tank or spraying equipment.  Many stories of failure come from this negligence and it simply is a must and part of the due diligence of hygiene and commitment.

Overall it’s a great technique for accelerating succession, getting farmers to convert to biological farming, and requires attention to detail and a systematic approach.  These liquid inoculants can be coupled with the keyline plough making a great implementation tool for tree crops or pasture renovation.  It’s a green business opportunity and employment possibility as training on the microscope and this technique becomes more common place.  Spreading the message about this innovative technology is important so that there is consumer demand to repeal the treadmill of synthetic, degenerative inputs.  Finally, individuals can also feel empowered to brew small quantities and create abundance throughout the system no matter the scale.

Written by Doug Crouch

Header art by Sien Verpoest


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  2. thanks for sharing : ) when you were here I remember your zest towards compost teas. Your article appeared at the right time for me, as I was just experimenting with compost tea, based on a recipe I got from Penny Livingston, she did recommend using molasses, which i didnt have, so in my experiment we used white sugar and hand vortex. Today our compost pile ((Doug style) is at 55C, so another experiment is due using the microscope and the learnings from your article. We have shared this way of making compost pile with tons of people, time to start making the brews as well and share it. Thanks!

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