Savvy growers, instead of reaching for the chemicals, look to a cue from Mother Nature in their search for effective biological products that can prevent and treat certain fungal diseases. The most notable are a specific group of naturally occurring bacteria that can be used to prevent and control fungal infections. These bacteria are called Bacillus subtilis and Bacillus pumilis.

So what are these strange Latin names and, most importantly, how can we use these bacteria to help us grow healthier, happier, and more productive plants? We asked Emily Walter from Agraquest, a provider of biological and low-chemical pest management solutions, to give us the lowdown on our friendly neighborhood fungal disease controllers.

Fungal diseases are a common issue among gardeners. And some of the more common diseases that gardeners struggle to control are powdery mildew and botrytis. Mildew can cause significant damage on some plants. It’s a common, but rarely fatal disease which affects many different types of plants. Most gardeners resort to removing infected plants, but often, the best strategy combines control and treatment.

So What Exactly Is Powdery Mildew?

Powdery mildew is a fungal disease that causes patches of white to gray powder on leaves, stems, fruits or flowers of infected plants. These patches can grow to cover the entire surface on both sides of leaves. Different strains of fungi cause the disease on different plants, but they are all similar in appearance. On some types of plants, the mildew will cause leaves to yellow and prematurely drop, or can cause stunted or deformed plant growth, and eventual plant decline. Mildew thrives in cool, damp conditions with poor air circulation. Indoor and greenhouse growers listen up!

What about Botrytis?

The dreaded botrytis or ‘gray mold’ is a fungal disease that infects many annual and perennial plants. There are several species of the fungus botrytis which can cause significant plant damage; the most common is Botrytis cinerea. Botrytis infections are favored by cool and humid conditions, and are most common during rainy spring and summer weather when temperatures hover around 60°F (15°C). Gray mold can take hold and spread rapidly if your indoor garden sustains long periods of high relative humidity, or outdoors when rainy, drizzly weather continues over several days. Botrytis can affect leaves, stems, crowns, flowers, flower buds, seeds, seedlings, bulbs and just about any other part of a plant with the exception of the roots.

[Left] Scanning Electron Micrograph (SEM) showing a healthy fungal spore on the surface of a leaf. [Rigth] SEM showing a destroyed fungal spore after foliar application of the beneficial bacteria Bacillus subtilis strain QST713. The Bacillus bacteria are the small rod shaped organisms around the top of the picture.

Steps Towards Prevention

Good cultural practices can help prevent and control the spread of fungal issues. The first and most important step toward prevention is to select healthy plants in the first place; these will be more likely to resist fungal attacks.

Plant breeders often select specimens that show resistance to common fungal diseases. This has lead to many different varieties of fruits, flowers and vegetables that have an ever increasing resistance to fungal diseases.

If you have no choice but to use susceptible types of plants outdoors, make sure they are in full sun and will receive a minimum of six hours of sun each day. Isn’t UV radiation great? Indoors, however tempting as it may be, never overcrowd your plants! Allow plenty of fresh air to circulate around your plants, this will discourage disease. When growing indoors, it’s absolutely crucial to focus on maintaining adequate ventilation.

Carefully remove infected fruits, flowers or mildew covered leaves. It is best not to do any removal of diseased plant when they are wet with dew or rain since this could spread fungal spores during conditions which favor infections. Likewise, avoid overhead watering or misting plants especially if fungal disease has been troublesome in the past.

If you encounter a heavily infected leaf, fruit, or flower and are worried about spreading spores around your garden, carefully cover the moldy item with a plastic bag before attempting removal. This way, spores end up in the bag rather than all over your garden!

Always throw away infect plant debris instead of placing it on the compost pile. Spores can overwinter on diseased plant material. New spores can be carried by the wind, so destroying the infected plant parts are essential to help stop the spread of plant disease pathogens.
In an effort to keep fungal diseases at bay, it’s good general practice to keep your indoor garden as clean and tidy as possible. Avoid leaving yellowing or dead leaves hanging from plants, and never keep piles old leaves and trash bags in or near you indoor garden.

Fungal Control Options

There are many chemical controls on the market but they do have some drawbacks. Some controls have temperature and timing restrictions impacting applications or harvest of your crops. Some diseases become resistant to certain chemicals over time as well. If you are using IPM (Integrated Pest Management) in the garden, you will want to preserve beneficial insects, which can be impacted by some chemical controls. Additionally, not all chemical fungicide treatments are acceptable for consumable plants. Some chemicals can only be used when the plant is dormant or cannot be used when the plant is close to harvest time. Carefully read fungicide labels to discover which is right for your particular need.

Beneficial Bacteria – Bacillus as a Fungicide

Another way to control plant diseases is to use products based on beneficial bacterial, specifically Bacillis subtilis or Bacillis pumilis. Both of these bacteria are common found in soil and have been used in horticulture and agriculture for many years.

Bacillus subtilis are naturally-occurring soil borne bacteria, fist characterized in 1835. Over the years varying strains of B. subtilis have been widely used for industrial processes (like detergents or waste water treatments). Bacillus subtilis strains produce extremely photo – and temperature – stable bacterial spores, making them ideal for gardening applications. B. subtilis is also Generally Regarded As Safe (GRAS) by the EPA.

Some strains of Bacillus subtilis are active ingredients in highly effective, broad-spectrum contact fungicides and bactericides. The Bacillus subtilis in these products produce lipopeptides, which are anti-fungal metabolites and anti-bacterial compounds. These lipopeptide compounds that Bacillus subtilis produce kill fungal spores and they are highly stable, resistant to elevated temp and pH extremes.

Lipopeptides are small peptide rings with a lipid (fat) attached. One end of the lipopeptide is negatively charged, the other is “greasy”. A fungal cell membrane can be compared to a sandwich – with hydrophilic (water-loving) surface and a lipophilic (fat-liking) core. The lipopeptides insert into those fungal cell membranes and create small holes in a fungal spore. As, they puncture the cell membrane, cell contents leak out and the fungus is killed.

Some B. subtilis products rely on prolonged wet periods on the leaf surface for the bacteria to become active, produce lipopeptides and then out-compete the fungal spores for leaf surface area. This is not the case with all products – the specific Bacillus subtilis strain QST 713 is unique in that it does not require time to activate, since the bacteria have already done their job producing the lipopeptide metabolites during production. Information about the active ingredient and how it works should be found on the container label of the product you decide to use.

Some Bacillus subtilis strains also illicit plant health and growth promotion in treated plants.  When applied, these strains can trigger the plants’ internal defenses and physiological responses. The effect is systemic – responses are triggered throughout the plant even when a small area is treated.

Products based on Bacillus subtilis are widely used by gardeners and commercial growers since they offer broad spectrum control, have little potential for resistance, have no temperature or time restrictions for application, are non-toxic to beneficial insects (including honey bees) and can be used up to and including the day of harvest. Some products based on B. subtilis are approved for organic production. Since Bacillus subtilis are non-toxic to beneficial insects you can use predatory insects for pest control and beneficial bacteria for disease prevention.

Products based on Bacillus pumilis strains are useful for gardeners for similar reasons. While products based on B. subtilis destroy fungal cell membranes, products based on B. pumilis instead focus on fungal cell walls. The compounds produced by B. pumilis compete with fungal diseases for amino sugars needed to build cell walls, effectively making it impossible for fungal cells to build and grow. B. pumilis does not control bacterial diseases. Instead, it is strongest against rust and mildews. B. pumilis is typically used by a gardener when targeting a specific type of fungal infection that is better controlled by this specific bacteria over the more broad spectrum approach of B. subtilis. Also, B. pumilis strains, like those of B. subtilis, have been shown to trigger plant’s natural defenses.

Both of these beneficial bacteria are best used when applied to plants in a preventative disease control program or at the very first sign of disease. Beneficial bacteria can be used in conjunction with other gardening products. Bacillus subtilis and Bacillus pumilis can be applied every seven days up to the day of harvest if needed. Beneficial bacteria can be applied more often if needed such as every four days during heavy disease pressure. When applying either type of bacteria as a foliar spray one should spay the leaves, shoots and new growth until the plant is dripping wet. Run-off spray will not affect beneficial soil fungi like mycorrhiza. When a gardener is planning to use beneficial bacteria or an organic gardening product to prevent or control fungal and bacterial diseases they should scout the garden often to look for any signs of disease. Strains of these beneficial bacterial can also be found in some compost teas since it can promote plant health and growth promotion.

Practical Tips:

When Do I Use It?

Most Bacillus subtilis or pumilus products can be sprayed as a preventative measure or be used as a curative control. They can be applied early on in the plant’s lifecycle on established cuttings or seedlings, and as late as the day of harvest on mature plants. Most growers freak out at the mere idea of spraying mature flowers or ripe fruit, but these natural Bacillus products are safe for human consumption and actively kill fungal growth.

Spray timing

When using outdoors, it’s best to spray in early morning or late afternoon when light intensity is not too strong. Sunlight contains a natural broad spectrum microbe inhibitor, Ultra Violet light. If applied during strong sunlight, the UV may prevent some Bacillus products from working effectively.
When spraying indoors, it’s also good practice to spray in low light. This may mean raising your grow lights up high before spraying, or spray just before the lights come on or go off.

Spraying the plants

The best fungal control is achieved when the plants are thoroughly wet, and run-off spray is dripping from the leaves. It’s a good idea to use a wetting agent for increased coverage. Avoid adding other foliar additives or nutrients as this may interact negatively with the beneficial bacteria. Spray the underside and top side of the leaves as well as any exposed stems. Sprays can be repeated every 3-4 days if plants are heavily infected, or every 7-10 days as a preventative.

What products contain Bacillus subtilis or pumilus for foliar fungal disease control?

Most good quality compost teas will contain some Bacillus subtilis and pumilus strains, so regular spraying can help with disease prevention. For a more targeted fungal control, the patented Bacillus subtilis strain QST 713 can be found in the commercial product ‘Serenade.’

Other Bacillus subtilis strains are used for root disease control, these include strains GB 03 found in the microbial inoculant ‘Companion’ and strain MBI 600 found pre-mixed into the substrate ‘Pro Mix MX with BioFungicide’.

“We know more about the movement of celestial bodies than we do about the soil underfoot.”
~Leonardo da Vinci

Commercial grape growers in Sonoma and Napa pay big bucks for beneficial biology consultants to come to their vineyards. And for good reason—the right blend of microbiology in their soils can significantly increase the market value of their wine by promoting more sophisticated flavors and bouquets in their grapes. When it comes to actually selling the end product, it can be the difference between producing a bottle that sells for, say, ten bucks and one that sets you back fifty or more. Just think what an understanding of beneficial biology could do for the fruit and veggies in your garden?

Organic waste decomposing at a composting facility in sacramento, California.

So what exactly is this beneficial biology? How do we ‘capture it’ and put it to work in our gardens? It turns out that the answer’s been right beneath our noses all this time. Literally! Microbes form an integral component of all living systems. In fact, if microbes didn’t exist then you wouldn’t be worrying about them, because you wouldn’t be around either! While you ponder that fact, consider one more. There are more microbial cells in and on a human (or at least one not taking antibiotics) than there are human cells in your body!

We’re going to find out how to breed microbes (it’s easy!) and deploy them in our gardens. To this end we’ve pulled in beneficial biology expert, Evan Folds from Progress Earth, to give us a practical introduction to brewing your own compost tea–and using it to grow the most delicious, chi-filled produce imaginable!

Salivating? Then you’d best read on!

Give it up for microorganisms! They perform relatively Herculean acts for their size. Microbes are responsible for aiding limitless plant processes, including helping plants feed and protecting them from disease. They even help to create the very soil that serves to support the entirety of life on Earth.  Meanwhile, many of us have become conditioned by modern marketing to foster a disdain and disrespect for microbial creatures (think hand sanitizers and antibiotics.) Healthy soil is alive with microbes. They form incredibly important mutualistic relationships with the plants we depend on for food. They break down organic matter (which is inaccessible to plants) into a form that plants can use. Think of them as little ‘compost conversion’ factories. Now start to imagine the potential for increasing the life force in your garden by learning how to breed these microbes at home! We’re talking about something called “actively aerated compost tea” or AACT for short. It’s “life juice” for your plants—a brown soup that’s full of beneficial microbiology, the essential components of any organic growing situation.

Compost Tea and Soil Food Web

Bubbling air through compost tea is essential to create a healthy, earthy-smelling brew

Brewing compost tea is easy and can be done in many different ways. You take some compost and other humus sources as a source for microorganisms and grow them to extremely high concentrations in an aerated water solution comprised of food sources and catalysts. The result? The soil food web unleashed in all its glory! Microbes and plants are natural teammates, so compost tea is simply the best way to replenish and enhance this wonderful relationship.

However, our current understanding of how to best take advantage of compost tea when growing plants can be called “rule of thumb,” at best. We know a lot about microbes, but relatively little about what they do or how to use them while growing plants.

Adding compost tea to rain water

There are potentially billions of microorganisms and thousands of feet of fungal hyphae in a mere teaspoon of quality compost. The fact is, microbes are so abundant, so pervasive in everything we do, that it’s no issue to promote astronomical numbers when discussing and marketing them in compost, or compost tea products. It’s easy to get bamboozled with all the hype surrounding compost and compost tea. Consider this: microbes are so small that up to 500,000 bacteria can fit in the period at the end of this sentence. When it comes to brewing your own microbes, high numbers are the easy part, but the number of microbes present in a biological sample is nowhere near as important as the diversity and strength of those organisms. Total numbers can be relevant when evaluating the balance of biological products or whether a humus product is stable, but it does not address the most important aspect of all—how well the product works in a real-life growing situation.

Biological Diversity and Microbe Strength

Many biological products available at your local grow store are created by microbes raised by humans in a laboratory. This biosynthetic approach is necessary for the cost effective distribution of certain microbes and has its merits, especially with mycorrhizae fungi, which cannot express their abilities without a plant and are not benefitted by brewing in compost teas. However, I believe that a biosynthetic approach cannot represent the full potential of an intact biological network. There’s no synergy amongst the different microbes as they didn’t grow up together. Remember, microbes aren’t robots, they’re unique dynamic living breathing life forms with varying abilities, even within a given species.

A key concept to grasp is that no living organism operates autonomously. In other words, there is a symbiosis, or “give and take,” found in the natural world that we humans take for granted, and therefore restrict. Think you grow your plants? Sorry but it’s far more likely that you merely get in the way and mess with the magic! All microbes operate by way of teammates. They play off of each other, with one teammate unlocking the ability of the next. The big man cannot dunk without the assistance from the point guard. When 52 different organisms (ones that were individually grown by a human in a Petri dish) are brought together as an end product intended for use in a gardening situation, the optimal result is surely compromised. Remaining with our basketball analogy for a moment longer, the team’s overall ability is hindered if all the players are not on the court and, even if they’re all present, what happens if the coach puts the players in the wrong positions?

Sure, microbes don’t play basketball (as far as we know) so you may be forgiven for thinking that it’s not feasible to identify ability in microbes. But first, check out some Bt products. Bt is a bacterium called Bacillus thuringiensis. It’s commonly used in gardening because it’s gentle with plants, but very capable of parasitizing the larval stage of common pest insects. The Bt organisms geared towards fighting larvae such as caterpillars are called the kurstaki strain and the Bt aimed at fighting mosquito larvae in water is named the israelensis strain. These organisms are of the same species and illustrate differing abilities depending on the application.

Microbes can react and adapt…by design. Did you hear about the “new” proteobacteria discovered by scientists in the wake of the recent oil spill? Look it up. BP must have been stoked!

Making and Using Actively Aerated Compost Tea

So, you want to brew your own compost tea. Where do you start? The answer is humus! Microorganisms are found dormant in quality humus sources like compost or worm castings, but can be awakened and stimulated to grow under the right conditions. There are several different methods for creating compost tea (AACT). It’s simply a matter of adding your humus source to water and using air pumps to increase the amount of air in the water solution in order to grow microbes. The final part of the jigsaw is to add some sort of food and catalysts for the microbes to grow, such as molasses, kelp, rock dust, fish, humate, sea minerals, etc.

Brewing your own AACT is similar to running an aquarium. You aerate water for fish the same way you do for microbes, or for roots in a deep-water-culture hydroponics system.

The porous bag allows microbes to escape and enter the solution while keeping the tea free from debris.

DIY Compost Tea Shopping List

You can purchase ready-to-go brewers if you want to make your life nice and easy. Alternatively you can make one yourself. To brew compost tea, you’ll need a pump, some air tubing, a gang valve, and three bubblers.

• An aquarium pump large enough to run three bubblers or air stones
• Several feet of tubing
• A gang valve
• Three bubblers
• A porous bag for the compost, like a nylon stocking OR Something to strain the final tea, like an old pillowcase or tea towel.
• A bucket

All the components of your own compost tea brewer can be obtained at your local garden store for around $60. Without sophisticated equipment it’s hard to determine technical aspects like dissolved oxygen, so it’s best to keep it simple. A small aquarium air pump is sufficient for up to 10 gallons. More air will not be harmful; it’s simply that water can only hold so much of it. If you want to use higher volumes of water, you may want to consider getting a larger air pump.

As your compost tea brews (it usually takes about 12––24 hours) you will notice a layer of foam forming on the surface. This is nothing to worry about and is actually a result of the proteins produced by biological growth. This foam is a good sign that your compost tea (or rather the microbial life within) is flourishing.

Deliberate overuse of bat guano.

Some foods sources such as bat guano create more of it, but a good fish oil (or the active ingredient in comfrey called allantoin) will keep things in motion and keep the foam down if need be. Foam is generally not a concern, especially when using suggested recipes from reputable compost tea companies.

When brewing AACT keep in mind that the higher the water temperature the greater the biological growth, but the lower the dissolved oxygen. It’s a matter of physics that the warmer the water temperature, the less oxygen can be dissolved. It is also true that the colder the water temperature the slower the biological growth. Dissolved oxygen levels above 6 parts per million (ppm) will provide sufficient biological growth, and levels around 8 ppm are attainable at room temperature. An accepted approach among compost tea enthusiasts is to brew AACT at a similar temperature to where it’s being used, for example; if your root zone temperature is 68°F (20°C), brew the AACT around this temperature.

The food source utilized when brewing compost tea can determine the microbe grown. This idea follows the concept of succession. An acre of land left fallow will begin to regenerate using annual plants (weeds), and then progress into more perennial species (grass, vegetables) until it culminates into a forest (perennial hardwoods). Over the course of this natural process, fungi become gradually more dominant than bacteria. This is not black and white, but is evident in the fungal dominance of old growth forests.

So what does this knowledge mean? Well, you can use it to brew compost teas that make more sense to what you are growing. For instance, a sugar source like molasses fed to a balanced stable compost inoculant will encourage more bacterial growth, whereas kelp or fish fed to the same inoculant will encourage more fungal growth. The same is true for other inputs, like Equisetum (horsetail), which encourages the growth of beneficial nematodes. To be clear, molasses does not discourage fungi from growing, it simply encourages bacteria more. Similarly, using a fungal dominant tea on an annual plant will not harm it in any way; it’s a better/best scenario. There is so much more to be discovered as da Vinci reminds us—we know more about the stars.

Using AACT

Microbes given a proper environment can grow to extraordinarily high concentrations. The book Secrets of the Soil states that a single microbe reaching maturity and dividing within less than half an hour can, in the course of a single day, grow into 300 million more, and in another day to more than the number of human beings that have ever lived. Further, according to the book Microcosmos, bacteria, in four days of unlimited growth, could outnumber all the protons and even all the quarks estimated to exist within the universe. This reality allows growers to use as little as five gallons on an entire acre of land, roughly equivalent to about a one cup per gallon dilution.

Compost tea can be used in unlimited ways and really cannot be used incorrectly unless you are overwatering your plants. Some growers choose to use compost tea on every watering, but weekly applications or on reservoir changes would be sufficient. It is even possible to experience benefits from compost tea with just one application. After all, you’re dealing with living organisms that can populate and reproduce by themselves if given proper conditions.

It is a common supposition that synthetic products (i.e. mineral based nutrients) kill microbes. While this is certainly true on some level, using compost tea with synthetic nutrient regiments can produce good results. The image inset illustrates the use of a leading compost tea brew used at one cup per gallon on weekly reservoir changes in a mineral-based hydroponic situation growing jalapenos.

Again, it’s a better/best scenario; you’re better off using compost tea and mitigating the potential harshness of your mineral-based nutrients than worrying about the microbes dying.

It is always advisable to check nutrient concentrations with a meter before using a tea on sensitive or special plants, but by keeping inputs at or near recommended amounts there should be no fear of burning. “Burning” a plant is actually a water stress based on total ion concentration. Having too many ions around a root system sucks water out of the plant via osmosis, causing the plant to respond by sending its available water into the middle of the leaf and leaving the edge to burn. Because compost tea is created at relatively low concentrations (600-800 ppm) burning is a non-issue when used at recommended levels.

As if to underline the previous point, compost tea can be used with seedlings and cuttings with great success. The sooner and more microbes used the better, even in hydroponics. Use a gallon of compost tea to 20-50 gallons of water in hydro reservoirs; some growers even use compost tea concentrate as their primary reservoir solutions. Consider using organic and organic-based nutrients as food sources for biological inoculants. It is not necessary to feed microbes after you have implemented them into a garden, but it can certainly have a positive influence. After all, natural farming is about feeding microbes, not the plant.

Compost Tea as a Foliar Application

You can even use compost tea as a foliar spray. Some growers spray their plants every day, but once a week will do the trick for measureable results. When using compost tea you are harnessing a synergy of living microbes for general benefit, however, this is one of the occasions when a targeted biological product can be effective. Many times the microbes used in human designed microbial products are found naturally in compost, but not in high enough concentrations to make them applicable once pests or disease have struck. In the end, a pest or disease is simply a biological imbalance of some sort, so when one trophic level gets out of whack a higher concentration of a certain microbe can work effectively.

The active ingredient in many biological fungicides is the bacterium Bacillus subtilis, which is found naturally in compost. This concentrated organism will work better on a disease outbreak, but if used consistently, compost tea can work preventatively to allow the disease to express itself in the first place. The more consistent you are in delivering microbes to the leaves and root zone of your plants, the more benefits you will receive.

Compost tea can even help control pests if used consistently, many bacteria found in compost seek protein, which is what comprises the exoskeleton of many target pest species. As with any new endeavor in the garden, isolate a test plot and experiment before implementing it into the entire growing situation.

There is no real precedent for using Actively Aerated Microbial Extracts (AAME) in compost tea brews, but it’s certainly a good idea for experimentation. Some grow stores set up multiple compost tea units for grow/bloom or bacterial/fungal purposes. I anticipate that we will start seeing them for pest and disease control too in the near future.

AACT Brewers

There are varied compost tea units available on the market, everything from a five gallon bucket to large commercial units. For the most part, the unit you choose will be based on volume size and convenience, not biological performance.

There is a healthy debate regarding the importance of the size of the air bubble produced by air diffusers and another on whether they need to be used at all. While it is certainly true that the smaller the bubble the more surface area exposed to the solution, it is unclear whether this really makes a difference based on maximum dissolved oxygen levels considering water holds a finite amount of oxygen relative to its temperature.

Filter bags to hold compost are also a point of difference between respective models. They are used strictly for convenience so that the compost tea brew does not clog up sprayers after creation. This can save time, but must be balanced with what is not extracted from the physical compost when brewing. As mentioned above, microbes hold on really tight. A quality humus is colloidal and most inputs used are soluble, so a filter bag is not absolutely necessary. You can always filter it after you are done brewing.

It is vital to use quality water when brewing compost tea, and in your garden in general. If you are unsure of your water source, use a filter. There are quality reverse osmosis (RO) filters and de-chlorinators on the market for reasonable prices. Most nutrient solutions are not designed to account for what comes through the tap, so if possible start from zero ppm. Remember, chlorine kills microbes and it’s added to just about every public water supply in some form for this very reason. Bubbling your water will remove chlorine in a couple of hours, but not chloramines, its more persistent cousins—also used in many municipal water supplies. At the very least, let your water sit out for 24 hours before using it to brew tea. Ideally, invest in a reverse osmosis water purification system.

Composts, Inoculants and Food Sources for Compost Tea

When brewing compost tea, starting with a quality microbial product is essential. This is a major problem with people who compost in their back yards. Organic matter doesn’t melt; it’s biologically digested. It’s not advisable to use manure to make compost tea because manure is not yet plant food. This is why black cow “compost” at the hardware store costs $1 a bag. It’s aged manure. It’s mulch, not plant food. Remember, trees in a forest don’t eat leaves; they eat what the microbes make of them.

Some growers use worm casings as the sole basis for their compost teas. While this is certainly a viable option to brew tea, worms are predominately a bacterial organism, and do not contain some of the trophic levels of beneficial organisms, such as fungi, nematodes, protozoa, ciliates, etc. that provide vital benefits to plants and gardens. Worms sequester bacteria in their gut in order to work their magic, like termites use fungi to digest the wood they eat. To brew a better tea, consider using worm castings along with a balanced humus product.

Food sources for compost tea include molasses, kelp, fish, bat guano, and generally anything that was once alive that is soluble enough to be put into solution, even fruit pulp. It is important to note that recipes and preferences vary widely, for instance, some may recommend up to 16 tablespoons of molasses per 5 gallons of water, others only 1 tablespoon. Be sure to experiment based on these general recommendations, but here are a couple of simple recipes:

Use the formulating company’s recommendations for humus and catalyst per gallon, then for a bacterial dominant tea, use 4-6 tablespoons of molasses and 2-4 tablespoons of kelp to five gallons of aerated water. Reverse the ratio for a more fungal dominant tea.

Three Simple AACT Recipes (All for 5 Gallon (19L) brewers)

Bacterial Dominant Tea

1.5 pounds (700g) bacterial compost or vermicompost
3-4 tablespoons (45-60ml) liquid black strap molasses
4 teaspoons (23g) dry soluble kelp or 2 tablespoons of liquid kelp
3-4 teaspoons (15-20ml) fish emulsion

Equal Ratio – Fungi : Bacteria Tea

1.5 pounds (700g) 1:1 fungi to bacteria compost
3-4 tablespoons (45-60ml) humic acids
4 teaspoons (23g) dry soluble kelp or 2 tablespoons of liquid kelp
3-4 teaspoons (15-20ml) fish hydrolysate

Fungal Dominant Tea

2 pounds (900g) fungal compost
3-4 tablespoons (50ml) humic acids
2 teaspoons (10ml) yucca extract
4 teaspoons (23g) dry soluble kelp or 2 tablespoons of liquid kelp
4-5 teaspoons (20-25ml) fish hydrolysate

Recipes from ‘The Compost Tea Brewing Manual’, 5th Edition by Dr Elaine Ingham.

Fish-based natural fertilizers are generally obtained in one of two forms, condensed fish solubles known as emulsions, or enzymatic digested fish known as hydrolysates. Fish hydrolysate is cold processed (minced, enzymatically digested and liquefied) to preserve proteins for quick turnover by microbes into nutrients for plants. Emulsions are created using extreme heat, and while they may be easier to work with because they are further refined, the processing removes valuable ingredients and denaturing nutrients. While both fertilizer forms can benefit a compost tea, hydrolysates retain the natural oils from the fish that are a very potent fungal food.

Mineral Catalysts

One thing that is not discussed enough in the compost tea community is the use of mineral catalysts. Catalysts, as we know, change the speed of a reaction. It’s important to understand that microbes work indirectly via chemical decomposition. In other words, bacteria don’t chew on a banana peel in a compost pile, they offer up an enzyme (biological catalyst) that works to chemically break it down. Enzymes are specialty proteins that work like keys to a lock for important biochemical reactions within living organisms, plants and people included. All enzymes incorporate a single molecule of a trace mineral—such as manganese, copper, iron or zinc—without which an enzyme cannot function. We all know the benefits of adding enzymes to our gardening systems, but not many growers know that you get free enzymes from microbes.

Microbes help plants eat and, in return, plants feed microbes. In fact, over half of the energy derived through photosynthesis by plants is fed to the soil as exudates. Think of an exudate as a meal for microbes. Plants actually know what they need, they just can’t tell us. This means that plants have the ability to attract specific trophic levels (imagine the balance of the big fish and the little fish in the ocean) of microbes by preparing food from its surrounding environment that attracts those capable of generating what is deficient in the plant. This biological/plant network, or intelligence, if you will, cannot be established overnight, but it can be tapped into if we are aware of it. This is especially true when growing indoors in artificial environments.

It’s important to provide everything for plants so they can be allowed to eat what they desire, but it’s even more important to allow microbes a complete tool kit. Not doing so is like hiring someone to build a house and only providing them half the tools. The pictures inset illustrates a side-by-side conducted with a broad-spectrum mineral product. The tea sample on the left was brewed in the presence of many more elements than the tea sample on the right. Note the enhanced foaming and darker color after only four hours.

Other catalysts to consider are rock dusts, yucca extract, or any broad-spectrum natural mineral. Remember, these materials are not “food” for microbes; they help microbes eat their food.

Buying AACT

Your grow store might be one of the many who offer up their own in-store brew from units operated inside the store. If you choose to purchase compost tea from a gardening store, be sure to use it as soon as possible. We have seen evidence of beneficial life for up to three days under a microscope with some systems, but it is always advisable to use it the day you get it from the shop. Make sure to ask your retailer about the components of the compost tea being brewed, including the biological source and whether mineral catalysts are being used. If they have a microscope set up, even better. Make a habit of reconciling the microbes you see under the scope before you take it home with the results you are getting in your garden.

Some models found in stores involve refrigerating brews and coordinating pickups on certain days, while others encourage running the units perpetually by adding food source, catalysts, and microbes daily based on the amount of water added to the unit.

Brew Times

The most commonly heard figure for brew times is 12-24 hours. If pressed for why, a common answer is because bacteria are most active in these stages. While bacteria are beneficial to plants, so are many other microorganisms. Take protozoa for example. It is well known that compost tea brewed for over 24 hours begins to develop protozoa and ciliate dominance. (The brew “matures.”) Protozoa are extremely efficient nitrogen (N) cyclers, so why would a grower looking for more nitrogen not brew their tea longer to populate more protozoa dominance? Further, they are also the shredders in the soil; they eat bacteria and fungi like a shark eats fish in the ocean. Humus is actually the guts of microbes. They have digested available organic matter to create stable dormant humus (plant food). The guts of microbes are actually fertilizer bags. Why wouldn’t we want protozoa in there creating nature’s plant food shredding up bacteria?

There is no “right” way to brew compost tea, only better and best. Before long we will have developed biological feeding schedules that direct growers on how long to brew their compost teas given humus, foods, and catalysts to accomplish the microbe spectrum that makes sense for the plant and stage of growth, like we do mineral products. If one wants bacteria to use as a foliar, use molasses and brew for 12 hours. For a higher fungal: bacteria ratio for hardwoods, brew 24 hours using fish hydrolosate and humates. Feed hay has shown promise in increasing protozoa counts, so brewers can use it and brew for 48 hours to sequester more for their gardens. The possibilities are endless.

Some growers are experimenting with aerating their microbes for a period of time before adding food sources. The idea is that some microbes wake up faster than others, so brewing without food lets all of them get their feet on the ground, so to speak. Makes sense, but much more research needs to be conducted. The new frontier in natural gardening will develop around these ideas. One thing is for sure, we’ve got a lot of work to do. But, hey, it could be worse, we could be sitting in a cubicle.

If we approach the biological situation of our soils and hydro systems humbly, we will be in a far greater position to benefit. We can get more out of our plants than we have come to expect. Growing plants is about much more than feeding a plant directly, it’s about taking stock of their total environment, including the biological (microbial) and energetic (biodynamic) aspects of the growing situation. Rather than listen to ourselves, let’s listen to our plants for a change.

If you’ve never used compost tea with your plants, you’re not maximizing the genetic potential of your garden. Consider this your clarion call. Stop by your local garden store and get started today.

“Nutrition as it is today does not supply the strength necessary for manifesting the spirit in physical life. A bridge can no longer be built from thinking to will and action. Food plants no longer contain the forces people need for this. So long as one feeds on food from unhealthy soil, the spirit will lack the stamina to free itself from the prison of the body.”   —  Rudolf Steiner • Creator of Biodynamics (1861-1925)

WORDS: Evan Folds

DESIGNING A HYBRID AERO-FOG-SWC SYSTEM

This system irrigates each plant in three different ways, yet it’s blissfully simple. It’s essentially a modular re-circulating system which incorporates: shallow water culture (SWC) aeroponics misters and aeroponic foggers.

Each plant gets the VIP treatment, basking in a 20 gallon Rubbermaid container! Wow! There are 70 plant containers in total. They are all joined together via ¾” tubing. Nutrient solution is pumped from an underground 55 gallon reservoir with a 1546 gallon per hour pump to the middle of each container. Within each container there’s a large ¾” flexible PVC irrigation ring with 3 x 180° misting nozzles ready to rumble. When the misters are on, the container gets filled with small droplets of nutrient solution, the droplets that don’t get absorbed by the roots fall to fill the bottom of the containers. As the container fills past 2.5 gallons, the solution reaches an overflow tube, from here it returns through ¾” PVC pipe back to the main reservoir.

After running a few tests Devin adjusted the return pipe to the reservoir to make it a more direct return. The foggers are set to spray for almost 7 minutes on and off for 4 minutes. This timing is deliberately adjusted so that sometimes there is only fog, sometimes fog and sprinklers, and sometimes sprinklers half the time and fog half the time. The timers are set so that different watering techniques are activated at different times in different combinations. The logic is the plant won’t get too used to anything and it also allows the root zone to dry a little, encouraging the root hairs to go in search for food. This makes the roots very tenacious, white, and strong.

As soon as the solution returns back to the 55 gallon from the overflow the system kicks back on. The return takes almost 4 minutes. When spraying the roots, the solution comes from the 55 gal reservoir, and it takes just 7 minutes to empty the 55 gal. This is the maximum watering duration that Devin feels he can achieve without getting a bigger reservoir.

In the bottom of each container is a 4” air stone, these are connected to 4 x 750psi air compressors to infuse the 2.5 gallons of nutrient solution with oxygen rich bubbles. Sounds just like an interesting re-circulating system right? Well here is the secret to this high yielding system…

Each container has an aeroponic fogger floating just under the surface of the nutrient solution. Each fogger has three disks. These foggers are on a 5 minute on, 5 minute off cycle to create an extremely fine mist or ‘fog’ with a particle size of 3-5 microns! Such a fine fog of nutrient solution creates supercharged roots with an abundance of fine root hairs. These root hairs can take up water and nutrients at a rapid rate creating explosive plant growth. This technique of utilizing ultra sonic foggers to deliver a nutrient fog to the roots has been recently dubbed ‘Fogponics’, although officially it falls under the banner of aeroponic cultivation.

AEROPONIC FOGGERS

Aeroponic foggers come in various shapes and sizes but all utilize the same technology. They work by sending ultrasonic frequencies to ceramic disks which sit just below the surface of the water. These ultrasonic frequencies vibrate the disk which oscillates the water above creating an ultra fine fog. This fog has such a small particle size that it feels dry to the touch yet it can easily penetrate roots without totally saturating them.

CHALLENGES

1) Foggers

The main drawback of using most foggers with nutrient solutions is they can become clogged very quickly with nutrient precipitate. Even using foggers in hard water alone can cause a quick build up of lime scale, let alone adding mineral salts to the mix, so how does this extreme aeroponic system get around this?

Through trial and error and with some help from Ryan Clout at Sunflower Supply and the online garden forums, these crazy cats found a solution. Devin located a company online selling Teflon coated disks that are longer lasting and keep residues from building up on the disk surface. This drastically prolongs the life of the foggers reducing the need for constant cleaning and frequent replacements.

As mentioned previously, the foggers need to be just below the surface of the water in order to emit the ultra-fine fog. To enable the water level in the container to rise and fall while still allowing the fogger work it became clear that the fogger would have to float. So armed with a tiny budget and a trip to the dollar store, the floats for the foggers were created from play snorkels and net cups for only a dollar for each fogger!

2) Solution Temperature

While in operation, the foggers generate a significant amount of heat that gets soaked up into the nutrient solution. Even with the solution circulating from a large reservoir around all the containers, the temperature of the solution in the bottom of the containers was quickly rising to beyond 75°F. Ideally the nutrient solution should be around 65°F for optimal levels of dissolved oxygen and nutrient uptake. This was a tough nut to crack. The way forward was to cool the nutrient solution and, being and inventive bunch of growers, they decided to make their very own homemade water chiller.

Using an old freezer (2ftx2ftx4ft) as the cooling chamber the crew drilled two ¾” holes through the casing, one near the top and one near the bottom. The cooling mechanism was created by constructing a coil made from 25ft of aluminum tubing. This fitted perfectly into a five gallon bucket which had a drilled hole at the top and bottom. This allowed the ends of the coil to come through. Then, they fed a ½” hose into each of the holes in the freezer, used silicone to seal the holes, and connected them to the coil lines. After making sure the hose and coil were watertight, they used non-toxic propylene glycol antifreeze to fill the five gallon bucket and popped a lid on it.

This homemade chiller is located next to the underground 55 gallon reservoir with the upper ½” hose connected to a pump in the bottom of the reservoir and the lower hose draining the chilled solution back into to the reservoir. This constant flow of nutrient solution being pushed through the chiller created a constant nutrient solution temperature in the reservoir of 60°F, with the containers stabilizing at 70°F, keeping the heat emitted by the foggers under control.

3) Environment

Being in the heart of Southern Oregon, air temperature during summer is also an issue for this aeroponic set-up. The roots are particularly susceptible to extremes in temperature as there is no growing media to act as insulation. On a nice sunny day, an outside temperature of 75°F can easily create up to 100°F in the greenhouse and that’s with the 24 inch ventilation fan and both 24 inch passive shutter inlets open! To keep temperature down on hot days a 25,000 BTU air conditioner was incorporated. It also doubles up as a heater for those cold nights in winter.

SYSTEM ENHANCEMENT

The secret to the system is the hybridizing of SWC, aero-sprayers, and the ultra fine fog creating by the foggers. Studies in the late 90s by NASA have shown that solely using ultra sonic foggers to feed plant roots creates a disproportionate amount of root hair with significantly less lateral root growth, making ‘fogponics’ less suitable for prolonged plant growth – i.e. bringing plants to full maturity. By combining the two aeroponic techniques of fogging and misting upper root zone and utilizing SWC to supply water, dissolved oxygen and nutrients to the lower branching roots, they have achieved the best of both worlds.

One key aspect of this hybrid system that Devin is keen on maintaining is a high beneficial microbe count, particularly predatory nematodes, in the growing media and nutrient solution. The beneficial nematodes are an excellent predator of fungus and bacteria, which Devin is sure will help keep the system clean.

To provide a good home for the microbes to hang out and breed, they have come up with a media mix for the net pots of 5 parts Hydroton to 1 part ‘loose fill’ Sure To Grow. Devin and the crew feel that this mix provides them with the ideal surface area for the microbes to stay happy.

To inoculate the system with tons of beneficial microbes they brew their very own worm compost tea!

DEVIN’S WORM COMPOST TEA

Step 1: To 16 gallons of reverse osmosis water, add 1 fluid oz (28.5ml) of fulvic acid and 1 oz of brewers’ yeast (used for home brewing beer and wine).

Step 2: Add 2.1 fluid oz (60ml) of Humboldt Honey Hydro ES to provide food and energy for the microbes.

Step 3: Add 4 teaspoons (20ml) of Cutting Edge Solutions’ calcium carbonate, the microbes to love it!

Step 4: Take 15” x 23”brew craft fine screen mesh bag and add 2.5 pounds of worm castings.

Step 5: Add and air stone (attached to an air pump) to the mix.

Step 6: Steep the worm casting bag in to solution for 72 hours.

Step 7: Remove the bag, give it a few squeezes and let the solution brew for another 12 hours.

Step 8: Prepare the nutrient solution, Devin uses Cutting Edge 3 part formula.

Step 9: Add the 16 gallons of fresh worm tea to 300 gallons of nutrient solution.

Using this technique the crew manage to brew a full 16 gallons for $15! With this fresh brew of beneficial microbes Devin says you can’t add too much. They even spray the mix on the plants in vegetative growth stage which they have found works best neat or at a minimum dose of 1 part tea to 5 parts water.

Using a plant viable form of calcium carbonate really works wonders. Microbes like to have some kind of nutritional buffer, whether it’s a little bit of potassium or even phosphorus, they just need some kind of mineral to feed off. Devin noticed that his nematode population is 10-15% higher when he used calcium carbonate. He used Cutting Edge Solutions’ calcium carbonate – once you open it you really must use within eight weeks, otherwise it can get susceptible to mold.

Using this concentrated homemade worm-tea the growers find they only need to use ½ to ¾ strength nutrient solution! The main reason is that the worm-tea contains a huge population of predatory nematodes and protozoa (single celled organisms that are found across several kingdoms). They are non algal, and non fungal (such as amoebaes, ciliates, and flagellates) and are the number one predators to bacteria and fungi alike. These little worm-like parasites are nasty little buggers. They are heterotrophic which means they cannot produce their own food. Instead they hunt bacteria and fungi while remaining harmless to you and your plants. They locate and shred apart the fungal mycelia and bodies of bacterial organisms which then provide plant available nutrients and minerals to the root system. It’s a beautiful circle!

Freshly brewed, actively-aerated compost tea and compost tea brewing machines with ready-to-use brewing kits are also available from several companies.

We recommend you check out:

• Vermi-T from Vermicrop Organics
• Progress Earth
• Nature Technologies International
• Bountea

To complete the beneficial microbe mix, they add other beneficial liquid additives. These include Canna’s Cannazyme and Botanicare’s Aquashield. Also, check out Sub Culture B from General Hydroponics.

Every two weeks they change out the nutrient solution for a fresh batch. To empty the system all they need to do is open up three taps – this allows the solution to run out through pipe work onto an outdoor vegetable plot, putting even the ‘waste’ nutrient to good use. To fill the whole system they prepare a 300 gallon reservoir which pumps the fresh solution to each container.

Devin has extensive hydroponic experience with flood and drain tables, drain to waste systems, Deep Water Culture, aeroponics, soilless and soil yet finds this hybrid shallow water culture/aeroponic/fogponic system the most sanitary, easier to clean with the least amount of nutritional and pest problems.

To provide support for the plants they use tomato cages fitted into the exterior of the net pots. This offers great support and allows the branches to be trained out, which in turn enables the plant access to more light, better support, more growth and more fruit!!!!

The assemblage of all these high yielding methods with a few tweaks has provided Devin and his crew an affordable homemade system that that they can literally (and physically) grow trees in!

WHAT DO YOU THINK OF THIS

SYSTEM? ARE THESE GUYS DESTINED FOR GREATNESS OR WHAT?

Special thanks to Ryan at Sunflower Supplies (www.sunflowersupplies.com) for his help with the ultrasonic foggers!

In the first and second installment of this series, Lawrence Brooke, founder of General Hydroponics, took us through how to maintain a healthy growing environment and some methods of dealing with plant sickness.  In this third and final part we look at how to introduce beneficial biologicals into a hydroponic growing system.

Biofilters

Think of beneficial biologicals and you probably imagine them in an organic / soil environment.  However, it’s also perfectly feasible to introduce them into a hydroponic growing environment using a Biofilter.  These devices are available at any aquarium / fish supply store (and some grow stores) and can assist in the maintenance of colonies of beneficial microorganisms for hydroponic systems.  Biofilters can also help to keep your nutrient solution cleaner and more aerated.  The very high surface area, combined with constant flow that aerates the solution 24 / 7 – this, in turn, creates an ideal environment for the beneficial organisms while removing discarded compounds that plant roots exude.

It is, of course, essential to provide an inoculation of beneficials to create the population in the first place; the Biofilter gives them a base-camp to operate from.

It’s very important to use products that are designed to operate in a hydroponic nutrient solution.  Your first job is to establish mychorizzae colonies on the roots.  A week or so later, add colonies of beneficial bacteria. Don’t go the other way or the bacteria will dominate the mychorizzae. Once a population is established very little needs to be added later, just a small amount each week or with nutrient changes, or after treating the plants with a ‘shield’ or neem product that has been applied as a drench. Nb. The drench method involves inoculating each plant individually using a watering can.  It is easy, effective and more economical than adding products directly to the reservoir where huge amounts of water can require larger doses.

In effect the biofilter draws in from your nutrient stream, then with its own built in pump circulates the nutrient across a matrix of high-surface area media. They are sized according to the reservoir size.

So if you’re one of the many growers who want to try using organic nutrients in a hydroponic system, make sure you invest in a biofilter!  For regular hydroponic use with purified soluble mineral based nutrients, an additional benefit is that you can usually get equal or better growing results with milder nutrient, save some money and reduce environmental stress from discarded nutrient.  Exponents of this method believe that this mixture of living nutrients but with purified soluble minerals leads to better tasting produce.  If you want to experiment, my best advice is to mix your nutrient solution using a high-quality hydroponic nutrient product, making it milder by about one third, and keep your biofilter running 24/7.

Who’s for a Brew?

Another powerful tool is the addition of ‘tea’ containing beneficials to the nutrient stream, and in some cases for foliar spray, irrigation, for germination and cuttings.  This isn’t the sort of tea Brits have with cake in the middle of the afternoon.  We’re talking about high quality ‘compost tea’.

Compost tea should be looked at as a process, not a product.  There is a broad range of systems and inoculants that are promoted as being good for plants.  The key to producing excellent compost tea is extreme aeration since the high oxygen in the solution will favor beneficials and challenge most disease organisms.  Typically both good and bad organisms are in the starting inoculant, usually Compost or ‘Forest Litter’.  “Alaska Humus” is popular and proven as an excellent starter for compost tea. It contains the huge spectrum of organisms that have evolved in arctic forests for thousands of years. Alaska Humus is basically forest top-soil.  The bio-diversity is enormous and generally favors beneficials.  The use of forest litter for making tea brings in beneficial fungi, bacteria and other symbiotic organisms; generally a much larger diversity than compost alone can provide. If you use compost then the quality of the tea will be directly related to the quality of the compost…. Good compost = good tea, nasty slimy compost = trouble. For more information read ‘Teaming with Microbes’ by Jeff Lowenfels, published by Timber Press.

For those growers who prefer ‘Organic’ products and methods, compost tea is the embodiment of the organic method.  It’s not just natural, it’s alive and vibrant.  The natural forests of the world grow without external inputs of fertilizer because the beneficial microorganisms in soil, air and water are the tenders of plants and forests, feeding and protecting plants growing in the natural environment.

Water and Nutrient Quality

As I mentioned last time, good water is a great advantage, poor water is a real challenge for growers.  If you want to grow plants hydroponically, use only the highest quality plant food, designed specifically for hydroponics. Low grade plant foods and common fertilizers offer your plants poor and incomplete nutrition, cause pH drift, and sometimes contain impurities that can become toxic to hydroponic plants, particularly in the root zone… think of common garden fertilizers as ‘junk-food’ for plants; this includes all of the garden fertilizers sold at big-box stores. They are formulated with cheap, impure ingredients and totally incomplete and out of balance. If the primary ingredients are ‘Urea and  Ammonium Phosphate, with no Calcium or Magnesium … then they are designed to give your garden plants a quick ‘fix’ while slowly poisoning your soil. Only high-quality plant food can grow superior plants. Healthy plants grow faster, generate higher yields and are resistant to disease and insect infestation; they are better tasting and yields are much higher.

Are You Taking Notes?

Keep notes on your observations of make-up water EC, EC drift, pH drift, total water usage, temperature range, both nutrient and air and comments on crop health and progress.  When you mix fresh nutrient always measure carefully.  Keep an eye on pH and an especially close watch on nutrient strength (PPM, EC, dissolved solids). Look out for diseases and remove and destroy sick plants immediately. As a rule of thumb 1,000 ppm translates to .5 miliSiemen so you can interpret ppm from an EC meter, or EC from a ppm meter.  They are essentially the same meter, just different ways of expressing the information or conductivity / nutrient solution strength.

Control your nutrient temperature – use a heat mat under your reservoir or high quality aquarium heaters to warm nutrient in the winter and look for chillers to cool your nutrient in the summer if high nutrient temperature becomes an issue.  Remember, above 72°F (22°C) the oxygen content in a nutrient solution can drop quickly. Locate the reservoir remotely in a cooler room or underground for greenhouse cultivation if your environment lends itself.

Generally if you are growing in a hot and dry environment, and the plants are big and growing fast, it is usually best to run milder nutrient.  This is in part because the higher transpiration rate will increase EC in the nutrient. If it goes too high it can become toxic to the crop.  It is better to be too mild than too strong.  If you want to run stronger nutrient, then you need pure water, more light, airflow, cool temperatures and robust plants.  Extra C02 in the air-supply can pay off here, particularly for young plants during early vigorous growth.

As a last word, please don’t be overwhelmed or intimidated by all this information. Plants can tolerate quite a lot of stress and still produce well. On the other hand the grower who knows the questions and how to find answers is the one who will have consistently good crops. It is far easier to avoid problems through knowledge and proper technique than to fix them after they arise.

Happy growing!

What exactly is “bat guano” and why did it burn the $@#! out of my plants?

Because you used too much of it! Duh! High nitrogen bat guano is composed of the fresh bat poop on the bottom of the cave. After the guano miner dudes mine all the fresh stuff they start to mine the hard floor which is the high phosphorus bat guano. The high phosphorus guano is fossilized high nitrogen guano. Guano which is rich in nitrogen contains a considerable amount of ammonia and ammonium nitrate.  This is what gives the nitrogen component to the fertilizer. The nitrogen is released freely whereas the phosphorus and potassium are slower to release. This is what burned your plants. High nitrogen bat guano should be applied between 1-3 pounds per cubic yard. A tablespoon or two per five gallon pot. Take it easy!

Can you add too much compost tea?

There is good biology and bad biology. You only waste money by over-applying good biology. That is, unless you disturb the natural balance of the soil. In all our years of using compost tea we have never seen a negative effect – unless you drown your plants in it!

Can certain soils be “too rich” for some plants?

Yes, soil is a natural “buffer” for your plants but don’t think it will prevent you from totally frying your plants with too much fertilizer! Many people have proved this fact. Most problems arise through misapplication. Growers read teaspoon as tablespoon. Or guess that they put in 10 mills a liter instead of measuring it. Or they feed, feed, feed, feed, over and over again with no run off from the bottom of their pots. Or simply their pH is off. All these things are really common. Read the manufacturer’s instructions and don’t be afraid to call them up if you have question.

What’s best for fast growing veg? Pre-mixed products or a DIY mix?

Difficult question! In either case you should use a proper balanced soil. It needs good drainage, and rich with no more than 30% good quality compost: try to use 10-15 %.  For most growers (especially beginners) it’s better to buy a good quality soil than to try and make one up – but experienced growers sometimes enjoy the challenge or have a good recipe.

Do you have a tried and tested soil recipe?

The following recipes are great because they are so simple and very effective for growing heavy-feeding, sun-loving plants that enjoy lots of aeration around the roots.

Recipe 1
2 parts coco
2 parts peat
1 part earthworm castings
1 part perlite

Recipe 2
2 parts Sunshine no 4
½ part earthworm castings

Got an organic mix of your own you want to share with us? Tell us about it!

Life is a miracle and cultivating plants is part of that miracle. In caring for our plants we form a symbiotic relationship with them. We watch our plants grow and do everything we can to help them reach their full potential. When we harvest and consume our crops, those same plants we cared for help us to grow! Seasoned gardeners are aware that this is just one relationship, one link in the miraculous chain of life. It’s so marvelous that many beginner gardeners focus exclusively on that ‘link’ – maybe because it’s the one that happens to be most directly appreciable to our senses. But there is a whole universe right beneath our noses that exists just beyond our powers of vision. It is a hidden world of microbiology that exists in the soil itself. We tend to appreciate this indirectly through effects, rather than causes, observing a plant as “healthy” or “diseased.” But with a little knowledge, seasoned with some imagination (or a powerful microscope!) the true extent to which we share this world can be revealed and the way in which we care for our plants is transformed.

A World In A Teaspoon

Okay, enough romantic talk of Mother Nature. Let’s move on to some mind-blowing facts. And these facts really are mind-blowing! Don’t just “uhuh” as you read these. See if you can actually visualize what is about to be described:

Imagine taking a teaspoon and dipping it into some living soil. Lift it up and hold it in front of you. What do you see? A teaspoon of dirt?

A teaspoon of living soil contains 100 million to 1 billion bacteria, 1 to 40 miles of fungal hyphae, and 1,000-100,000 protozoa!

40 miles of fungal hyphae in one teaspoon!? Now do you see we’re talking about another world within our world? What are these organisms? Well, they are all part of this whole chain of life that helps to grow your plants. These organisms are as real as they are small. And in their huge numbers, they play a really important role in plant health and growth. The bacteria eat the exudates (simple sugars, carbons, carbohydrates) that the plant puts out through its roots, which are then eaten by the protozoa. What is excreted by the protozoa is now plant-available nutrients. Beneficial fungi protect the plant from pathogens and harmful microbes, as well as creating pathways in the soil that bring water and nutrients back to the plant from larger distances. Bacteria and fungi work together in decomposing organic material and making the nutrients plant-available. This is a sustainable process known as “nutrient cycling” that allows for the growth of healthy plants, without the need for fertilizers, pesticides, and other chemicals. After all, there’s no one out there putting Miracle-Gro on our rainforests each year, yet look at how successful plants are at growing in these microbial-rich environments!

The War on Terra

Most soil these days lacks the biology necessary to cycle nutrients to the plant and protect it. Where did they go? They were killed off by so-called modern agricultural methods or “the war on terra” – years of abuse including overuse of synthetic fertilizers, pesticides, fungicides, over-tilling, and compaction.

Chemical fertilizers and other -cides contain salts. Remember back to high school science where you learned about the process of osmosis? It’s the movement of water through a cell membrane from a solution of low solute concentration to a solution with high solute concentration. In living soil, water is locked up in the cells of the microorganisms. With the proper biology in place, you can cut back on your watering by up to 30%! When salts in the form of chemical inputs are added to the soil, the water is drawn out of the microbes and they are either killed or go into a dormant state. Now the plant is dependent on you to provide all of its food and protection. That’s why you have to fertilize on a regular basis.

In addition to damaging the biology in the soils, these chemicals are having other impacts of much greater consequence. Nitrates from fertilizers are leaching into our water system, and pesticide exposure has been linked to a variety of serious diseases such as cancer. There’s a reason that lawn companies recommend keeping children and pets off lawns after they’ve been sprayed. These chemicals are highly toxic!

So what’s the alternative? There is a shift from our current N-P-K paradigm towards an organic way of gardening by feeding the microbes in the soil and letting them do the work for us. Our ancient ancestors gardened in this manner long before we knew what bacteria were! Fertilizer was in the form of manures, which were decomposed by the microbes and provided all the nutrients the plant needed.

Creating Life in Soil Again: Compost Tea

Using present day technology, we are now able to add these beneficial organisms back into our soils and feed them through a variety of organic inputs. The three best things you can do for your soil is to top dress with compost, mulches, and compost tea. Since many of you probably already know about the benefits of compost and mulch, I’d like to focus a bit more on compost tea.

When I say compost tea, I’m referring to actively aerated compost tea, or AACT for short. This distinction is important because there is a big difference between throwing some compost or manure in a bucket and letting it sit for a couple of weeks, and AACT.

AACT is an aerobic water solution that has extracted the microbe population from compost along with its nutrients. The concept behind compost tea is quite simple, though the actual process becomes scientific and has many variables that need to be accounted for. The idea is that compost (full of beneficial microorganisms) is put into water and then nutrients or foods for the microorganisms are added to allow the bacteria and protozoa to multiply rapidly and the fungi to grow. Air is sent through the water to keep the dissolved oxygen levels above 6 mg/liter, as this selects for the aerobic microorganisms, which are the ones found to be most beneficial. At the end of the brewing cycle, what you have is a concentrated liquid literally teeming with billions of microorganisms that can be sprayed directly onto the leaf surface of your plants or onto your soil. This puts the “good” biology where the plant needs it to protect itself. It keeps the plant healthier and helps to fight off potential diseases. The “good” biology occupies the infection sites on the leaf surface and survives by consuming the exudates that the plant puts out. The “good” biology then out-competes the pathogens for the space on the leaf surface or around the roots (rhizosphere). This is how plants protect themselves and thrive in nature.

It is possible to make bad AACT. If you don’t start with good compost, don’t add the proper amount of nutrients, or keep the brew sufficiently aerated, you could be selecting for pathogens rather than beneficial microbes and end up with a tea that will have little to no effect on your plant or possibly even do damage.

Along with compost tea it’s important to do applications of other bio-amendments such as soluble seaweed, humic acids, and fish hydrolysate, for example. Seaweed serves as a bacterial food substrate and also provides additional benefits for your plants in the form of growth hormones, increased stress resistance, and faster plant response. Humic acids serve as a fungal food, and also chelate (bond with) minerals in your soil and make them available (many minerals in your soils are “locked up” or unavailable). These sorts of applications work by feeding the microbes, which in turn feed your plants.

When gardening in this manner, it’s important to adjust your application rates or program to fit within the needs of your garden. I’d suggest an initial topdressing of your garden with compost and an application of compost tea, adding soluble seaweed and humic acids to the tea after brewing. Then, another application 2-3 weeks before planting and another one when you plant your starters (adding mycorrhizal fungi into the hole at this time). In the fall, I’d add a mulch to your garden, followed by an application of compost tea (to speed up decomposition over the winter). You may or may not need an organic fertilizer (NPK below 10-10-10) to supplement the rest of your program.

Once an organic program has been established, typical application rates of AACT, humic acids, and seaweed are only 3-5 times per year. Now the plant is in charge, and the organisms are in place to cycle the nutrients for the plant. This is what sustainable gardening is all about!

WORDS: Tad Hussey, Keep It Simple, Inc. www.simplici-tea.com

THE BASICS

What is a Soil Amendment?

A soil amendment is just stuff you add to soil – either a single ingredient or a blend – to help combat micronutrient deficiencies, adjust pH, combat salts, introduce microbial activities, and so much more. But hey, don’t confuse soil amendments with fertilizers – these add formulated food for the purpose of the plant, while soil amendments are used to treat the soil itself. However, that said, many soil amendments are also used in blended fertilizers and provide feeding nutrition.

Types of Amendments

Soil amendments come in many different forms; most are organic, which is preferable for your soils, some are considered “natural” which are derived naturally though not necessarily organic, and some are synthetic. Organic amendments as well as naturally derived amendments are the best way to change your soils from a dead clay heap to a living, symbiotic organism. The categories of amendments include: bark products, plant byproducts, animal byproducts, manure-based, compost and mulch based, and rock and mineral powder based.

Do I Need a Soil Amendment?

As a rule of thumb, all soils love to be amended; the question actually lies in: which amendment do you need? It is best to have your soil tested for pH, micro nutrient deficiencies, salt content and more before applying products that will alter the nutrient value of your soil. Just because lime is a great amendment, it does not necessarily mean that you need it. When selecting a soil amendment you look for how long the amendment will last in the soil depending on your growing season; the soil texture and salinity; the plants you are planting; and the salt and pH content.

Which Amendment is Right for Me?

PLANT BYPRODUCTS

First, let’s take a look at the soil amendments that are made from plants:

Alfalfa Meal

Feeds with 3% nitrogen and is known to contain growth factors and mineral content. Very common ingredient in many blended organic fertilizers.

Coconut Fiber

Great aerator. Excellent soil amendment or a standalone grow medium. Coconut not only provides great aeration but also efficient transfer of nutrients. Check your source though, as coconut can be very salty and this can harm soils and plants.

Cottonseed Meal

Nitrogen super booster! (Between 6-7%.) Only “organic” if it was grown that way – most cotton farms use chemical foods and insecticides. So, check your source. Cottonseed meal is also a very common ingredient in blended fertilizers.

Seaweed

Adds micronutrients and plant hormones! Derived from varieties of kelp harvested from the ocean then dried and ground into a powder form. Contains small amounts of nitrogen, phosphorus, and potassium. Many forms include kelp extracts in which compounds are extracted from the seaweed to concentrate the micronutrients and other helpful plant hormones. They are not high enough to correct deficiencies, but kelp provides plants and soils with a vitamin like effect.

Soybean Meal

Adds vital nitrogen to the soil. Usually one of the more expensive amendments, but very useful.

Sphagnum Peat Moss

Great to add to rough soils. Improves moisture retention.

Wood Ash

Another soil softener. Adds essential phosphate and potash. Can be a little high in pH (very alkaline) so go easy on it. Great to add to very acidic soils that are high in nitrogen.

ANIMAL BYPRODUCTS

Blood Meal

Use with caution or risk burning your plants. It’s dried and ground waste from slaughterhouses, primarily steer, and is a strong source of nitrogen.

Bone Meal

Slow release. Another common ingredient in fertilizer mixes, and due to its high amounts of phosphorus, should be used with care like blood meal.

Earthworm Castings

Clean, usually odorless, and can be used on all soil and plants. Castings, when concentrated, are rich in nitrogen but they will not burn plants. Castings vary but can contain magnesium, calcium, potassium, potash, micronutrients, and some trace elements. Grain fed castings tend to be the best and stay in the soil longer, while manure fed castings are a lower grade, but release their nutrients faster. More importantly, worm castings contain tons of beneficial organisms and microbes that help to restore soil life and begin recreating the soil web.

Feather Meal

Products of the poultry industry, the feathers are ground into a meal which contains levels of nitrogen which releases a little slower than other nitrogen sources.

Fish Meal

Ground and dried fish waste. A good source of nitrogen and some phosphorous too. Not to be confused with fish emulsion, which is a liquid form of the fish waste products and less stable.

Oyster Shell Lime

Sometimes grouped with dolomite lime, however it is derived from the shells of finely ground oyster shells rather than being rock-based like dolomite lime. Oyster Shell lime will raise pH, add calcium, and many micronutrients. The microbial life inside of your soil loves oyster shell lime!

Phosphorous Bat Guano

King of the phosphorus amendments! Fantastic crop sweetener! Not to be confused with nitrogen bat guanos, which are more of a manure product, phosphorous bat guanos are ground up fossilized remains of bat poop. The phosphorus releases slowly into the soil over time and contains beneficial microbes too.

Shrimp, Crab, and Sea Meals

Ground waste products from sea going animals that are not fish. Their waste is primarily their shells and exoskeletons which provide an excellent source of major nutrients as well as many micro-nutrients. They break down slowly, thus providing some staying power.

MANURE-BASED AMENDMENTS

Nitrogen Bat Guanos

Bat droppings that are fresher provide a great source of nitrogen. They contain some phosphorus, though not as high of levels as the fossilized bat guanos. Nitrogen bat guano is considered to be the best of the manures as they are nutrient rich, but very stable.

Poultry Manure

Quick and dirty fix of nitrogen – releases very fast. One of the poorer quality manures, but effective if used quickly and properly treated. It can burn your plants, so it must be amended into the soil and watered in before planting. Fish meal is preferable as it is more stable and does not decompose as quickly.

Sewage Sludge / Bio-Solids

Very cheap, very dirty: derived from human waste and whatever else got flushed, such as traces of household chemicals, bleaches, and paints. It can contain many harmful pathogens and heavy metals. Not nice.

Steer Manure

The farmer’s stinky favorite. Derived from steers and some equine. Very potent source of nitrogen and should be used truly to amend soils in preparation of planting. Best for large gardens and not small landscapes or containers. In bagged form, it is still very volatile and breaks down quickly.

COMPOST-BASED AMENDMENTS

Compost

Derived from decayed plant matter such as your left over vegetable scraps. Compost does include decaying animal matter as well, but for most gardeners it comes from vegetable and fruit scraps from your home.

Mulch

Plant and bark materials that are not fully decomposed. Aids moisture retention, decreases temperatures (protects from hot temperatures), weed reduction, and more.

ROCK & MINERAL-BASED AMENDMENTS

Dolomite Lime

Provides calcium, magnesium, and lowers pH quickly. It also helps with the breaking up of clay soils.

Greensand

A clay-type mineral supplement, greensand will provide potassium on a slow release schedule. It is very effective at improving soil structures though not so much as a fertilizer.

Hard Rock Phosphate

Derived from volcanic deposits and highly mineral in composition. The phosphate is not as available as in more traditional, soft rock phosphates, so it is not always the best amendment. However, with its mineral qualities, it can provide slow and steady mineral release into soils.

Humates

Derived from leonardite, humic and fulvic acids, humates help with the active part of soil’s humus. These goodies help with nutrient uptake by plants and assist under the soil too.

Perlite

Volcanic rock “rice crispies.” Perlite is inert and provides drainage and aeration in to compacted soils. Perlite rises to the top when watered, so it is not the best to add to in-ground plantings, though very important for containers and raised beds.

Rock Phosphate

Excellent, slow releasing form of phosphorus. Many sources have been mined deeply and contain levels of arsenic, so get it tested or check your manufacturers MSDS (Material Safety Data Sheet).

Vermiculite

Vermiculite is very light and can float in water. It is a great medium for starting seeds and amending soils as it contains some minerals and will help with aeration. Perlite provides better results for drainage and aeration, though.

Q) What Exactly Is “Compost”?

A) Compost is organic matter that has gone through a decomposition process. The organic material can be plant material or animal matter. Composting may seem complicated but it’s actually just a natural process that continuously occurs in nature without any assistance from mankind. It is the natural top soil in the woods. Both living plants and annual plants that die or drop plant matter are consumed by animals, large mammals, birds, rodents, worms, insects, and microscopic organisms.  The results of this natural cycle is compost, the remains are left on the forest floor to create rich, soft, earthy smelling soil.  Mmmmm!

Q) Where Does The Compost I Buy Come From?

A) Commercial composters work with waste haulers and organic waste generators to provide an alternative to landfills, leading to a reduction in the generator’s waste management costs. The material is diverted to a composting facility where it can be recycled into soil amendments and other value-added products.

Q) Can I Make Compost At Home?

A) Absolutely!  DIY Home composting helps to keep the organic material out of landfills and in turn makes a wonderful product for your garden. Composting at home is even greener and reduces the transportation. But don’t worry if you decide you don’t have the time or the room to do it yourself; most states have mandated waste management facilities to divert the greater portion of organic matter from the landfill to a composting facility. This has lead to an increase in the availability of mass-produced compost.  You can do your part by buying this lush beautiful soil amendment!

Q) What Makes Compost Good for Plants?

A) Compost is great for the environment and great for the garden.  Compost improves the soil by providing all of the essential nutrients plants need to thrive.  It releases the nutrients slowly over time giving the plants a slow, steady consistent source of the elements plants need.  Compost also improves soil porosity, structure, moisture capacity and air ratio.  Compost will improve the texture of any soil from sand to clay. Field testing has shown that compost improves plant vigor, overall health and the plant’s immune system.

Q) Where Can I Buy Compost?

A) Compost is available in most retail garden centers and is typically sold in 1 to 2 cubic foot bags.  Keep in mind the name “compost” is used generically and does not constitute its quality.  The mandates that forced the hands of garbage waste companies to compost organic matter has created some compost facilities that simply just do it because they have to. These companies are focused on the reduction of garbage and not quality compost. So look at the compost before you purchase it and ask yourself… Is it rich in color? Does it have a soft earthy smell? Is it free from garbage and large chunks of un-composted material?  If the answer is yes to all of these questions you are most likely working with a decent material. For more detailed information on the compost you purchased call the manufacture and ask for a soil analysis. If they are not happy to provide it find a company who is!  

Q) How do I Make My Own Quality Compost?

There are two basic kinds of compost piles: open bins and enclosed containers.

Typically composting at home is done in a pile, an open bin, or an enclosed container. A pile or open bin usually has little to no starting costs and it’s very easy to add your feeding materials.  Also, it will collect rain water easily.  Some considerations if you are planning a pile or open bin compost pile: it will attract wildlife, it can be an eye sore, it can get overly drenched during the rainy season and it can smell really bad! Also keep in mind you have turn the pile once in a while.

Container composting can either be done in an upright box or a rotating drum. These options are great at keeping out pests and are a bit easier on the eyes for you and your neighbors. Pay attention to the moisture content and be sure to turn your container as needed.

Compost Basics

Temperature: Letting the compost pile core heat to 160°F (71°C) will be beneficial for the decomposition of the material and will also kill off pathogenic organisms.  It will heat up naturally during the decomposition process.

Air and Water: Keeping your pile moist is simple.  However, keeping it oxygenated is more work. As the pile heats, the microbiology goes to work and, as the pile settles, the air flow is cut off and the pile becomes anaerobic. This is where we get our shovels out and turn the pile, flip our containers, or roll our barrels thus fluffing the pile and allowing the airflow to return.

Feeding your compost:

There are two basic categories of food source for a compost pile.  Although one or any combination of these materials will compost a good mix of them will compost more efficiently.  A good rule of thumb is about one part green and three parts brown; too much green creates smell and off-gasses some of your nutrients.  Too much brown will slow the process.

Typical green materials for compost are:

• Fresh (green) grass clippings
• Fresh manure (horse, chicken, rabbit, cow)
• Kitchen scraps (fruit, vegetables, coffee grounds, tea bags.  Avoid meats and fish.)
• Weeds
• Green leaves
• Leftover fruits from the garden

Typical brown materials for compost include:

• Brown, dry leaves
• Dried grass
• Cornstalks (shredded)
• Straw
• Sawdust

In conclusion, composting is great for the environment and fantastic for your garden. There are a lot of resources on composting but the best way to learn is to go for it and get your hands dirty!

All sounds rather slick, right? After all, the key to huge harvests is providing a whole spectrum of optimum conditions for your plants – like a series of links in a chain. However, there’s one thing missing from this garden – an essential building block of the sort of harvests your plants want to give you. MICROBES.

Beneficial Microbes

Microbes may be small, but they’re taking off in a big way as indoor gardeners discover new ways to harness the benefits they bring. And leading the pack is John Perrino of Vermicrop Organics, California.  He’s taken some time out from his crazy microbial world to explain what microbes are, what they do, and how we urban gardeners can use them to take our gardens to the next level.

Perhaps I shouldn’t attempt to summarize everything in the first sentence, but here goes: Beneficial microbes increase the efficiency of your nutrients. Put another way, microbes allow your plants to feed more. Even the highest quality nutrients can be made more efficient through microbiology, thus increasing growth, vigor, sugars and yields. Ok, so now you know what beneficial microbes are basically about – but let’s look a bit deeper!

The basic application of beneficial microbiology in soil and hydroponic gardening is simple, really. It kind of falls under the same concept as the food chain. When a plant’s root system has a well-rounded colony of micro-organisms, it has billions of microbes doing a wide range of jobs. Some microbes consume nutrients; some microbes consume the microbes that have consumed the nutrients, thus breaking the nutrients down into a smaller form. This allows the nutrient to be absorbed by the plant more efficiently. Other microbes defend against unbeneficial microbes and keep the plant’s natural defense system at its peak performance level. Each microbe exudes different types of enzymes, proteins, acids and other essential elements. These are the elements needed to break down trace minerals, micro nutrients, and macro nutrients making them immediately available as a food source to the plant. All this really means is an explosive increase in root mass, which equals increased nutrient uptake, which equals bigger yields!!!

So if these beneficial microbes are the building block to a robust and vigorous garden, how do we get them there in the first place? Remember, these little guys are living entities. So the best way to increase the levels of microbes in your gardening system is a fresh brewed, microbial rich solution. We are talking about Actively Aerated Microbial Extracts (AAME). Now, don’t switch off on me just because I’m using acronyms already. I’m telling you that AAMEs are going to change your life!  So listen up!

So What’s Brewing?

Actively Aerated Microbial Tea

Like I said, these little guys are LIVING so they’re going to need feeding. The idea behind AAME is to take an organic material that is high in beneficial aerobic microbes and add essential food sources to raise certain levels of each type of beneficial micro-organism. To get things to multiply, dissolved air and a food source in an aqueous environment is needed. But you have to create the right conditions for these little fellas to multiply at the rates we want – using water straight from the tap is a no-no (because of chlorine levels); reverse osmosis or de-chlorinated water at the perfect temperature and the right type of food sources will allow microbes to multiply at extremely rapid rates.

Beneficial Bacteria

There are three basic groups of beneficial micro-organisms (take note there are tens of thousands of individual types of each microbe in each group). The first to be addressed is beneficial bacteria, the smallest of the three groups. They attach to your root system and feed on unavailable nutrients in and around the root web. Once a bacterium has consumed a nutrient (food), the nutrient is then immobilized (locked inside of the bacteria’s cell wall).  Here the nutrient is broken down with a mixture of different proteins and enzymes. The only way that the nutrients can be unlocked (mineralized) and up-taken by the plant is if the bacteria dies and/or is consumed by a competing micro-organism. Once this process occurs, the nutrients are released in their mineralized form and are immediately absorbed by the plant.

Fungi

Fungi, the second group of beneficial micro-organisms, are much like bacteria in the sense that they too find and immobilize unavailable nutrients. Unlike bacteria, fungi find their nutrients in a completely different way. Fungi live in and around your root web, and grow miniscule root-like strands called “hyphae”; these strands can stretch for many feet. The hyphae stretch throughout the network of the plant’s root system, usually ending on an attachment site on the root. The nutrients are then distributed in a number of different ways. Immobilized nutrients are locked up within the cell walls of the hyphae until the fungal microbe dies and/or is consumed by a competing micro-organism. The nutrients then get mineralized and passed off to the plant as an “easy to absorb” food source. Other fungi trade exudates (carbohydrates, sugars and proteins made by plants and excreted by roots) for water and nutrients; these fungal organisms are known as mycorrhizae. Mycorrhizae work in a symbiotic relationship with the plant’s roots: the fungi brings nutrients and water back to the plant’s roots in exchange for exudates collected from the roots. It’s a win-win situation. The plant then becomes somewhat dependent on the fungi and the fungi cannot live without the exudates from the plant. Through this relationship, many different nutrients are mineralized and absorbed immediately by the plant.

Protozoa

The third type of beneficial micro-organism is the protozoa. Protozoa microbes can be up to 100 times the size of bacteria and fungi. The protozoa feed on mostly bacteria and fungi (protozoas can eat up to 10,000 bacteria a day). When the protozoa consume bacteria or fungi, they mineralize any of the nutrients that were immobilized in the bacteria or fungi. This unlocks any nutrients that have been locked up in the bacteria and fungi. They are then absorbed rapidly as a food source to the plant. Protozoa are at the top of the food chain in the beneficial microbe world. This means there always needs to be a food source, otherwise protozoa will die. Luckily, as the protozoa consume the microbes they consume small bits of organic matter that are processed and exuded as food sources for bacteria and fungi. This helps keep fungal and bacterial populations sustained when conditions are right. If fungal and bacterial populations diminish, protozoa will start to eat their own and eventually die. This is why it is important to replenish microbe populations with a balanced array of beneficial micro-organisms, keeping the food chain in balance and allowing optimal performance.

The only way to get an extremely high multiplication of micro-organisms is through a fresh extracted AAME. Unfortunately, Actively Aerated Microbial Extracts are not available as an ‘off-the-shelf’ product.  To solve this issue, an on-site extraction process with a culture of biology is necessary. This process can multiply the culture of aerobic micro-organisms over 9 billion times in a 24 hour period. When an AAME is used as a foliar spray and as a root inoculant, it will raise the number of micro-organisms that work together in a symbiotic relationship with the plant to increase vigor and yield. With a high diversity of beneficial micro-organisms, plants receive a wide array of the micro-organisms that exude humic, fulvic, amino acids and proteins. These micro-organisms and their exudates aid in immobilization and mineralization of trace elements, micro and macro nutrients.  Microbes have been around for millions of years and now we have the technology to put them to use in our gardens.

Microbe Tea – Q&A

You say actively aerated microbial extracts aren’t available ‘off-the-shelf’ – so once I’ve brewed the tea do I need to use it straight away?
No – think of it like milk. It will last for 12-24 hours if stored at room temperature, or 7-10 days in the refrigerator. Use the smell test. It should have an earthy and fresh aroma if it’s good. Smells damn awful when it’s gone bad!

How much microbial extract brew is good for my plants?
For Soil: Dilute with water at a rate of 75 ml to gallon (1:50). Apply this solution directly to your soil over the root zone.
For Hydro: Use the same dilution ratio but reintroduce more microbial tea solution to your nutrient solution every 7-10 days.

Can I use boiled tap water to make the microbial tea?
No, boiling won’t cut it. You must use non-chlorinated or Reverse Osmosis filtered water. Reverse osmosis machines are more affordable than you think. Check out the Small Boy made by Hydro-Logic.

What do you think about using microbes in your garden? Do you have any tips, tricks or stories to share?