C. 1. Understanding Compost Tea

1. Why Use compost tea?

Compost tea is used for two reasons: To inoculate microbial life into the soil or onto the foliage of plants, and to add soluble nutrients to the foliage or to the soil to feed the organisms and the plants present. The use of compost tea is suggested any time the organisms in the soil or on the plants are not at optimum levels. Chemical-based pesticides, fumigants, herbicides and some synthetic fertilizers kill a range of the beneficial microorganisms that encourage plant growth, while compost teas improve the life in the soil and on plant surfaces. High quality compost tea of will inoculate the leaf surface and soil with beneficial microorganisms, instead of destroying them.

What is compost Tea?

Compost tea is a liquid produced by leaching soluble nutrients and extracting bacteria, fungi, protozoa and nematodes from compost. The brewing process is performed at constant temperature, although the growth of the organisms may elevate temperature as a result of their reproductive heat produced.

Tea production is a brewing process, and as easy as making beer or wine. But we all know that wine or beer brewing isn’t that easy. Brewing compost tea can be fraught with problems. But if you think about what you are doing, and pick out the right tea-making machine, making compost tea that will help your plants is easy as flipping a light switch. What is your purpose in making tea? If you want to inoculate a highly beneficial group of bacteria and fungi, protozoa and possibly nematodes, buy good compost that has these organisms, and make Actively Aerated Compost Tea. There are a number of excellent tea makers on the market (see How to make AACT).

Benefits of using of compost tea containing the WHOLE foodweb include:

• Improve plant growth as a result of protecting plant surfaces with beneficial organisms which occupy infection sites and prevent disease-causing organisms from finding the plant,
• Improve plant growth as a result of improving nutrient retention in the soil, and therefore reduce fertilizer use, and loss of nutrients into ground- and surface waters
• Improve plant nutrition by increasing nutrient availability in the root system as predator-prey interactions increase plant available nutrients in exactly the right place, time and amounts that the plant needs,
• Reduce the negative impacts of chemical-based pesticides, herbicides and fertilizers on beneficial microorganisms in the ecosystem
• Improve uptake of nutrients by increasing foliar uptake as beneficial microorganisms increase the time stomates stay open, while at the same time reducing evaporative loss from the leaf surface,
• Reduce water loss, improve water-holding in the soil, and thus reduce water use in your system,
• Improve tillage by building better soil structure. Only the biology builds soil structure, and ALL the groups in the foodweb are required to be successful. You can’t have just bacteria, you must have fungi, protozoa, nematodes and microarthropods as well! Please be aware that plate count methods don’t tell you about the whole foodweb.

What is in compost tea?

Tea contains all the soluble nutrients extracted from the compost, but also contains all the species of bacteria, fungi, protozoa and nematodes in the compost. Not all the individuals in the compost, but representatives of all the species in the compost are found in the compost tea. Making sure only beneficial species are present in the compost is therefore critical.

Outdated methods of assessing numbers of organisms in samples might lead you to believe compost tea doesn’t have much diversity. But, consider that species diversity in soil is much, much greater than plate count data would lead people to believe. Plate counts miss 99.99% of the bacterial and fungal species in soil. You need to use molecular methods to understand true species diversity in compost.

Plate count assessments of diversity in compost and tea, and soil should not be used. They are misleading about the true diversity, or even as an indicator of diversity in soil, compost or compost tea. Good, aerobic compost contains a huge diversity of organisms.

Foods extracted from the compost, or added to the tea, grow beneficial organisms. A large diversity of food resources is extracted from compost. The species diversity of organisms in the tea is much higher than those hundred or so species of bacteria that grow on the food resources added by people. Together, the beneficial bacteria and fungi growing on the compost foods, and on the added foods, result in a many individuals of many different species. Molecular diversity analysis is required, however, to assess even a small portion of the species present in compost tea.

Only aerobes are desired. Anaerobes make alcohols that kill plant tissues very rapidly. Putrifying organic matter, which is anaerobic, also contains organisms, just not organisms that do anything beneficial for your plants.

Most introductory microbiology books can answer most questions about the controversy between direct enumeration and plate count approaches. Reading the sewage treatment literature also points out clearly the conditions that allow E. coli to grow, which means reduced oxygen atmosphere. In full aerobic conditions, only if the beneficial bacteria have been killed or harmed can E. coli win in competition with aerobic organisms.

The list of papers specific to compost tea and compost have been summarized by Steve Diver, and are listed on the ATTRA website, www.ATTRA.org

When buying a tea machine, you should ask the manufacturer to provide information about oxygen during the tea brewing cycle in the compost basket or bag. You should insist on being given molecular analyses of diversity, and total and active bacteria and fungi, and protozoa, present in the tea made under standard conditions.

The METHOD is critical in making tea

In order to have the organisms in the tea, brewing conditions must be correct to produce the end product desired.
The biology that is active and performing a function will be very different, depending on:

• temperature of brewing,
• the foods added to the brew,
• oxygen concentrations in the brewer during production,
• the initial compost used, and therefore which species are present to be extracted,
• The length of time tea is brewed.

Temperature

Temperature during brewing should be related to the temperature of the soil, or of the leaf surface. If tea is applied in the late autumn, when temperatures are cool, it may be wiser to apply a tea where the organisms are mostly asleep, or that are selected to grow on plant residues. Selection for this ability would be enhanced by addition of plant material to the brew, such as oatmeal, alfalfa meal, feathermeal, etc.

Foods

Foods added to a brew will select for particular species that can use those foods. Do you want a bacterial tea? Add sugars, simple proteins, simple carbohydrates. If a fungal brew is desired, add more complex foods, such as plant material (oatmeal, soybean meal, flour), humic acids, fulvic acids (which will release bacterial foods after fungi begin the process of decomposition). Predators can be enhanced by adding hay (cut green and dried), or by soaking hay for a few days and adding the water to the tea brew.

Oxygen

Oxygen is perhaps the parameter that has been least understood in centuries of tea-brewing. Most beneficial organisms, the organisms that promote the processes that plants need in order to grow without stress, and therefore with greatest resistance to disease, are aerobic organisms. To enhance this community of beneficials, tea must remain aerobic.

Fermentative microorganisms are organisms which can grow in aerobic as well as reduced oxygen conditions. Since these organisms have dual metabolic abilities, they have to maintain the genetic material for both sets of enzymes. They have an energetic load that means they are not as competitive with true aerobes, when oxygen is in fully aerobic concentrations. They are not as competitive when in competition with true anaerobes at low oxygen concentrations. They do best in the conditions where oxygen is fluctuating in the intermediate aerobic – anaerobic range. These organisms can make very interesting waste products when growing in anaerobic conditions. These materials are known to have significantly inhibitory effects on a variety of less-desirable organisms.

The problem is maintaining the conditions exactly correctly so that the desired organisms grow. This knowledge is not public domain, and remains proprietary. Until attention is directed to understanding what products result from different aerobic – anaerobic conditions, with which foods, and with different temperature regimes during brewing, fermentative compost teas remain in the questionable realm. These teas don’t produce the same effects time-after-time, which is the reason that compost teas have languished in the “snake-oil”, and “voo-doo-juice” category for so long. If the tea you brew today has one effect, but the tea you brew tomorrow has a different, and possibly negative effect, that lack of reliable results will destroy the reputation of a product. It is most important to clearly maintain production conditions when making tea.

Anaerobic conditions (below 2 to 4 mg oxygen per L for example) during brewing can result in the growth of some quite detrimental microbes and production of some very detrimental metabolites. It is best to avoid extremely low oxygen concentrations during brewing, or if low oxygen concentrations occur, brewing must continue until the organisms stop growing on the added foods, such that oxygen will diffuse back into the brew. Only after the brew returns to the aerobic conditions should it be used on plants or soil.

If you want to make a mix of unknown, but possibly quite anti-bacterial, or anti-fungal materials, then a fermentative approach might be best. The specific conditions needed for production of a consistent mix set of inhibitory substances are not well-documented. More work is needed to understand production parameters for this kind of tea.

Is compost or compost tea "better" if it is aerobic or anaerobic?

Bacteria that cause human diseases almost invariably require anaerobic or reduced oxygen conditions in order to survive in competition with aerobic organisms. Only in reduced oxygen, or anaerobic conditions, can human disease-causing organisms out-compete the normal set of beneficial bacteria or fungi growing in soil, compost or compost tea.

If you’ve done a good job choosing or making your compost, the compost will not contain any human disease organisms. The tea will not contain human pathogens if there were none in the compost. What do you need to know in order to be assured that the compost contains no human pathogens? The temperature cycle of the compost. Insist on getting that data from the compost maker. What do you care about the amount of nitrate, if there are human pathogens in the “compost”?

If the compost was kept fully aerobic, and temperatures between 135 F and 155 F were maintained for 10 to 14 days, or the compost was processed by adequate numbers of earthworms, the likelihood of human pathogens in the compost is just about nil. Contamination of finished compost by something else containing pathogens is possible so be aware that this can be a problem too.

If the compost wasn’t processed correctly and disease-causing organisms weren’t destroyed by temperature, competition with beneficial organisms, or passage through earthworms, the probability is reasonable that disease-causing organisms will grow rapidly and be in high numbers in a tea that goes through reduced oxygen, or anaerobic, conditions.

If the tea was made with good compost (high numbers of beneficial bacteria, fungi, protozoa, nematodes; good soluble nutrients) using aerobic conditions, there is little likelihood that human pathogens could grow, because not only are conditions not correct for their growth, but they will be out-competed and inhibited by the aerobic bacteria and fungi growing in those aerobic conditions.

It is critical to know that the tea maker you are using can maintain aeration rates greater than the rate the bacteria and fungi use up the oxygen.

Oxygen or carbon dioxide can be monitored to determine whether aeration is adequate throughout the whole brewing cycle, and in all parts of the machine. Please be aware that the data needed are from the inside of the compost basket, or inside the compost bag. Currently, all national level compost tea manufacturers display SFI data on their websites, with only two exceptions. People who bought machines from these two companies have sent data to SFI showing that either inside the compost baskets or the bags, the tea went anaerobic during tea brewing, or serious anaerobic bio-films develop in places that you can’t see or can’t reach easily during cleaning.

Oxygen in the tea should not fall below 5.5 to 6 ppm dissolved oxygen, which is typically about 70% dissolved oxygen, or 15 to 16% oxygen when measuring total atmospheric gases. These values change based on altitude and temperatures, so make sure the oxygen probe comes with information on typical maximum oxygen levels, which is where your water in your tea maker will start out.

You can’t tell whether oxygen use, or carbon dioxide production, was performed by bacteria or by fungi. Since you need to know, at least occasionally, the ratio of fungi to bacteria your tea, you need to test your teas so you can be certain you are making disease suppressive tea.

Fungi grow very well indeed in compost tea.

For good fungi in tea, first of all, fungi in the compost have to be extracted adequately. This is a function of two things, presence in fungi in the compost, and rapid enough water movement through the compost to pull the fungi off the compost particles. Work with Bruce Elliott of EPM (sales@composttea.com) has shown how easy it is to get great extraction and growth of fungi in the tea.

The EPM, KIS, WormGold, and BnBrewer machines in the US, Tea-riffic® in Canada, the Compost Tea machine in New Zealand, and Compara in Europe, in do excellent jobs of extracting fungi from the compost and allowing it to grow in the tea. Testing, over one to two years, shows that these machines continue to make good tea. Machines with hidden surfaces that develop biofilms do not maintain good tea production over time.

Sales people from companies that cannot pass SFI standards like to say that “fungi don’t grow in tea”, or “there are lots of fungi in the soil already”. Please realize that what they are actually telling you is that the machines they sell do a poor job of extracting fungi and growing fungi. Fungi can be extracted and grow quite well in tea.

When soils have been treated with fungicides, including copper sulfate, or sulfur, the soil cannot possibly maintain normal levels of beneficial fungi. Adequate beneficial fungal biomass does not occur in any field treated with fungicide, insecticide, bactericide, nematicide, herbicide or high levels of inorganic fertilizer.

Fungi require foods to feed them

If the compost contains complex food resources, that can be enough to feed many fungal species, but usually additions of humic acids, and complex nutrient resources enhance the growth of beneficial species. People involved in making tea often research nutrient food resources. Hendrikus Schraven Landscaping (gina@hendrikusorganics.com), EPM (sales@composttea.com) and Leon Hussy at KIS (www.simplici-tea.com) make some outstanding food resources for bacterial and fungal teas. Many ideas for foods for bacteria and fungi can be found on the compost_tea list serve, www.compost_tea@yahoogroups.com

Species diversity

Species diversity is the same in compost and the tea made from that compost. Species diversity in compost is higher than fumigated or sick soil. But at least one plate count microbiology lab is giving out data suggesting that compost has lower diversity than bad soil and that “ok” tea has less diversity than bad compost. It is clear that plate count “diversity” methods are not effective in assessing species diversity, or species richness, in soil, compost or compost tea. Molecular methods tell us that species diversity in soil, tea, and compost, can number in the thousands and tens of thousands per gram.

Use of methods that tell you that soil contains only a few 5 to 10 species, or that compost contains only 8 to 15 species need to be viewed with a great deal of incredulity. Plate methods are missing only about 99.9% of what is actually present!

Do plate counts or direct counts assess tea quality? The clear answer is that direct counts assess tea quality, while plate counts do not. Take a look at the results (below) from a test where two different teas were used to control blight on tomato plants.

Compost bags

Multi-layer fabric, or felt, bags are a poor idea, because the hyphae get held in the fabric, and mildew grows in the damp material. Single layer, nylon or netting bag material is necessary.

Time to brew

Small, well-aerated, well-mixed compost tea makers can give great tea within 10 to 12 hours. The KIS machine gets great organism extraction and growth of the beneficial organisms in 12 hours, based on direct counts of the individual bacteria, measurement of biovolume of fungal hyphae, enumeration of protozoa and nematodes from those teas.

Pay attention when you buy a machine or develop a design. Different tea machines take different amounts of time to brew good tea. Especially those machines that take 48 hours or more to brew a decent level of organisms in their tea, the salespeople tend to be very reluctant to tell you exactly how long the tea takes to reach a certain organisms-in-the-tea level. For example, some machines take a minimum of 48 hours to brew the tea, and as a result, tend to have more problems with becoming anaerobic.

Several “tea-brewer” manufacturers have no data about maximum bacterial or fungal production with their machine, and certainly no clue at all about protozoa or nematode numbers. Their salespeople will tell you their tea is ready in 24 hours, but they don’t have any data to prove this to you. Buyer beware!

What is the shelf life of compost tea?

The shelf life is short in high quality tea with active organisms necessary to attach to lead surfaces and not be washed off. In the research that we have done with 24 hour brewing cycles, after just 6 hours without any aeration, the oxygen levels are lowered by over 300 %. If the compost tea is not used within that time, aerate, agitate and add more food to the tea to feed the micro-organisms.

C. 2. How does the Foliar Food Web affect plants?

Foliar organisms create a protective layer on leaves, stems, blossoms, fruit and any above-ground just as happens in the soil, around roots.

This dynamic, living system on the aboveground parts of plants is constantly impacted by rain, wind, heat, sunlight, and pollution. Often disease can gain a foothold after some disturbance harms the community of beneficial, plant-surface dwelling organisms.

Understanding foliar health requires knowing:

1. what organisms should be present (community analysis),
2. how many are present (total biomass of each group), and
3. how many should be functioning (active biomass).

Healthy Leaves, Soil, or any System requires:

1. Organisms that cycle nutrients into the right forms at the right rates need to be present on the foliage in the right diversity, in the right number, in the right places (growing on the exudates plant surface release) with the right level of activity,
2. Organisms to prevent disease-causing organisms from being able to find a foot-hold on leaf or plant surfaces,
3. Organisms that cause plant stomates to open and remain open longer so nutrients added with the microbes will be pumped into the leave surfaces more rapidly, when the plant is supplying foods to make microbial activity occur,
4. Organisms to degrade toxic materials, especially air-borne pollutants,

Aren't organisms present in the soil, or on leaves, or in compost just automatically?

NO, they are not. Consider all the toxic chemicals human beings release on a daily basis. Consider air pollution. If air pollution is killing human beings, think of the damage to smaller, less well-protected individuals. Dust, and toxic pesticides and salts are being poured out onto soil, onto plant surfaces, each day. Natural disturbances (freeze, thaw, wet, dry, fire, and compaction) can kill critical organisms as well. We need to learn the impact of all disturbances, whether human-generated or natural occurrences. We need to learn how to replace, encourage and select for the presence of the appropriate organisms.

If nature kills organisms through natural disturbance, we need to know how to return to what is needed for the crops we want, just as we need to know how to return the organisms to what is needed after we use any chemical, for whatever reasons. It would be better not to let disturbance kill the organisms we want, but sometimes, we just don’t have any choice. We have to learn how to nurture the right biology and bring it back.

If anything has been harmed or reduced, or put out-of-balance, the appropriate organisms must be returned to the plant surfaces if they have been harmed or reduced in diversity or biomass. If the organisms that perform these benefits are missing, they need to be replaced.

The foliar food web will not contain the higher level predators. In unusual disease or pest outbreaks, such as ants farming aphids on foliage, it may be necessary to discourage the ants from this behavior by adding some ant-pathogenic fungi into their nests, or adding the fungi to the tea brew so the ants pick up the fungus and take it home with them on their feet.

Foliar pests can be discouraged by the smell, the taste, or the tackiness of the leave surface that foliar compost tea brews leave behind. The precise mechanism needs to be determined for why this works.

Bacteria are typically the dominant microbe on leaves, twigs, branches, blossoms and bark. Decomposer or saprophytic fungi are also present. Both bacteria and fungi use the exudates produced by the plant, by algae or lichen growing on plant surfaces or deposited by through-fall or other deposition processes. Maintenance of the proper coverage of organisms on the leaf surfaces is critical to maintaining disease suppression in the foliage of any plant.

How can the Soil and Foliar Food Web be assessed?

Methods have been developed that allow the numbers, types and activity of each important group in the soil and on plant surfaces to be quickly assessed. The kinds of assessments used are:

• Number of individuals or biomass of each group
• Type of organisms present and who is dominant
• How active the organisms are
• Relation of soil organisms to plant available nutrients

All of these methods need to be performed by direct microscopy, not by plate counts, enzyme assays, or other in-direct assessment methods.

Aeration must be adequate to extract the maximum amount of soluble nutrients, and to maintain oxygen in aerobic concentrations in order to produce a tea high in aerobic bacteria and fungi, and with maximum extraction of protozoa and nstrongatodes. The more diverse the community of microorganisms extracted and grown under aerobic conditions, the greater the disease suppression and the better nutrient retaining the tea will be. The greater the concentration of nutrients extracted, the more food there is to grow beneficial bacteria and fungi in the tea during the brewing cycle and after the tea is sprayed out.

It is CRITICAL to understand that tea must rstrongain aerobic. If too great a concentration of food resources for the bacteria and fungi are added, the growth of the organisms will be so rapid, that they will consume oxygen more rapidly than oxygen can be added into the tea. The tea will go anaerobic, and then human pathogens can grow in the tea.

Any compost tea machine can be caused to go anaerobic, if too much microbial food is added, too much compost, and aeration is lacking.

Compost tea is used to add bacteria, fungi, protozoa and nstrongatodes to the soil or onto foliage. Compost tea also contains soluble nutrients that feed the organisms in the tea and may feed plants. Use compost tea any time organisms in the soil or on the plants are lower than optimum levels. Chstrongical-based pesticides, fumigants, herbicides and some synthetic fertilizers kill the beneficial microorganisms that encourage plant growth, either in the soil or on foliage. Compost teas improve the life in the soil and on plant surfaces and help plants take-up the nutrients they require, and suppress diseases at the same time as building soil structure, and reduce erosion and loss of nutrients into drinking water. High quality compost tea of will inoculate the leaf surface and soil with beneficial microorganisms, instead of destroying thstrong.

Given a good set of organisms (see Compost Tea Standards for what those numbers are), the following benefits can be brought about:

• Improved plant growth
• Reduced application rates of chstrongical pesticides, herbicides and fertilizers
• Reduced impacts of chstrongical-based pesticides, herbicides and fertilizers on beneficial microorganisms in the ecosyststrong
• Occupation of infection sites on the plant surface so pathogens cannot infect the leaf
• Improved uptake of plant nutrients through influences on stomata,
• Increased numbers of organisms on and around plants to compete with disease-causing organisms, reducing disease incidence,
• Retention of microorganisms in soil or on leaf surfaces, resulting in an increase in retention of nutrients,
• Increased plant nutritional quality,
• Production costs are reduced
• Reduced application of toxic chstrongicals, thus reducing run-off into lakes and streams,
• Reduced toxic impacts on humans and pets.

Step-by-step Approach to Making AACT

One, choose a compost tea machine that has documented ability to extract and grow the beneficial organisms from the compost you are using.

Here’s a list of brewers on the market in the US. We will be putting up a list of brewers from outside the US in a short period of time.

Dstrongonstrated to Make Good Compost Tea, Grow Beneficial Fungi in the Tea Maker. These are not in any particular order!

1. EPM, Earth Tea Brewers – 100 ($3,500) and 500 gal Excellent extraction (composttea.com)
2. KIS brewers – 5 ($99) and 25 gal Good extraction, easy to clean!!!!! (simplici-tea.com)
3. Alaska Giant – 1 ($40) and 5 ($80) gal, good extraction, soaker hose (alaskagiant.com)
4. Ground Up – 50 gal and larger
5. Worm Gold (www.wormgold.com)
6. Compara
7. Sottilo - JAMSOT@aol.com Brewers made to order

Dstrongonstrated to grow bacteria, and usually only anaerobic bacteria
SoilSoup – 6.5 gal ($400), 30 gal, 250 gal (soilsoup.com)
Growing Solutions – 25 ($1300), 100 ($5000) and 500 ($12,000) gal (growingsolutions.com)

Figure out the amount of tea you need to put out at any one time. If you can put out 5 gal today, and 5 tomorrow, and 5 the day after, why buy a machine that makes 50 gal? If you own 10,000 acres, ok, you need a big machine. If you own an acre or less, a 5 gal machine will likely do fine.

Read and ask questions on the compost-tea list serve (http://groups.yahoo.com/) put 'compost_tea' in the search box, relative to each brewer you are considering.

You need a tea brewer that the seller can document oxygen rstrongains in the aerobic range!

Here’s a graph showing the type of information you need.

In this case, the red line is oxygen concentration in the water (in ppm or mg oxygen per L of water), and the green line is the active biology in the tea (micrograms of active bacteria and active fungi per ml of tea). When the organisms are growing the most rapidly, activity peaks (after about 16 hours in most brewers, although about hour 8 in small brewers).

The reason for the peak is that the microorganisms have maximized use of foods, and after that peak, their activity slows down, because they are running out of food. Activity usually stabilizes about 24 hours, so it is safe to take the tea out of the max aeration brewer and put it into a sprayer tank that has just re-circulation.

If the aeration is turned off, it typically takes some time for the organisms to use up the air, and plunge into anaerobic conditions. A truly stable tea would only slowly use up oxygen and go anaerobic, usually in about 5 to 6 hours. But if the tea is not in a stable condition, then when aeration is turned off, oxygen levels will plunge within mere minutes to low, anaerobic levels.

Two, find a GOOD source of compost! Ask the compost maker for documentation of the bacteria, fungi, protozoa and nstrongatodes in the compost. If they don’t have the data, they have probably tested, and couldn’t show that their compost really is compost. Lack of data often means they can’t make the grade. You have to have the beneficials in the compost in order to make good tea. You may want to read over the compost section of this website to find out the desired levels of the different organism groups.

Three, decide on the foods you want to use to grow the beneficial organisms in your tea. The company you bought your tea maker from has a proprietary blend of foods that go with their tea machine, balanced already for the oxygen-use of that set of foods, and the ability of the machine to replenish oxygen during the growth of those organisms. It is critical that aeration be adequate. Alternatively, you can design your own tea recipe, but this will take some testing to make sure you are NOT adding too much food, and reducing oxygen, through the growth of the beneficial organisms, below aerobic levels. Foods that should be considered are:

• a diversity of sugars for bacterial growth, but realize that often the compost itself contains adequate bacterial foods to grow a great set of bacteria. Addition of more bacterial foods can just cause problstrongs.
• Citric acid to help buffer pH to the right level, as well as feeding beneficial bacteria
• Cold-water kelp (higher in nutrients) to serve as a source of micro-nutrients (K, Co, B, etc, please check the label of the product you buy to make sure you are adding micronutrients you need. How do you know micronutrients are needed? A soil chstrongistry, or plant tissue test might be a good idea)
• Humic acids fro fungal growth, but realize that you want data to show you that this material can actually help grow fungi. Harsh extractants can make the humic materials very difficult for fungi, or anything else, to use.

Four, you need a means of transferring the tea from the tea brewer to the soil, or to the foliage of your plants. With small size tea brewers, pouring the tea into a sprayer works well. But with larger volumes of tea, you will need a transfer pump to move the tea into the sprayer unit. You need to talk to your tea machine maker and find out the testing that they have done to make certain that the pump doesn’t destroy the organisms in the tea as it is being transferred.

There is a tea maker on the market, clearly one not recommended by SFI, where the transfer pump kills about 50% of the organisms in the tea. So even though that company posts plate count data showing there is bacteria in the tea made by that machine, moving the tea out of that machine into your sprayer will kill about half the organisms in the tea. Please be aware of these kinds of snake-oil salesmen!

Five, you need a sprayer that will distribute the organisms evenly on the leaf surface. Typically any sprayer meant to apply pesticide will evenly apply tea organisms. The only thing that needs to be checked is that the sprayer re-circulates tea while the tea is in a large size tank (back-pack sprayers or smaller don’t need this, it typically doesn’t take hours to apply tea in small amounts), and that the pump used by the sprayer doesn’t kill organisms either. Talk to the tea machine makers about their lines of spray equipment.

Factors affecting Compost tea Quality

• Compost source – make sure it contains the organisms your plant needs
• Compost tea bag or container – the simpler the better, but opening sizes have to be right
• Brewing time – longer is not better
• Brewing tstrongperature – make it right for the syststrong the tea will be sprayed on!
• Water source – get rid of chlorine, chloramines, sulfur, other preservatives
• Extraction – the organisms have to be ripped off the compost, but not harmed in the process!
• Amount of tea applied to the soil or to the foliage – 5 gallons per acre for each 6 feet of foliage height, 20 gal per acre for the soil applications are the latest test results using EPM, KIS, BnBrewer, Clarke, AG, CT Brewer (NZ), and WormGold brewers.

The Pump

If you are going for the bigger machines, pay attention to the kind of pump on the machine. Did the manufacturer check to see if his pump kills organisms? Where are his data? Don't accept "trust me". There's a machine on the market that we dstrongonstrated to the manufacturer that his pump to take the tea from the brewer into a holding tank was reducing numbers of fungi and bacteria by 50%. Keep that in mind, when buying something. How are you getting large volumes OUT of the tank?

Ease in cleaning is important.

Can you get to the bottom of the tank? Are there square corners in the pipes, knowing that in a month or so, that corner will be bio-film filled. It isn't right away that the problstrong develops. With the commercial Microb-Brewer, altered from the original design we tested at OSU, the pipes and pumps were changed to make the machine look prettier. The numbers on the changed machine were similar to the original, not-pretty design for the first couple of runs, but then, look out, the numbers dropped terribly as the bio-film developed. The manufacturer claimed that our methods had gone awry, that we didn't know what we were doing, because the numbers were coming out lower. It wasn't us, it was bio-film. But the manufacturer got mad at me. Stopped speaking to me all together. Called me all sorts of bad things.

SFI just tests the tea, we don't have to know why the numbers are coming out poorly. Usually I try to figure it out, and with the Microb-Brewer, we did figure it out. But not until after the damage was done. The Microb-Brewer is no longer for sale in the US.

Are there surfaces in the machine you can't see, can't get to to clean? Those places build-up biofilm. There's a brewer on the market that has discs in it, and you can't see, and you can't reach, the bottom sides of the discs. It is not fun getting the discs out to clean their bottomsides. Think about the time involved in cleaning. Most LARGE brewers should have a way to rinse the tank down as you pump the tea out. Talk to Bruce Elliott on this one. He developed the solution for this.

The compost container has to allow free movement of the compost.

Solid baskets that don't allow compost movstrongent, that allow the compost to compact in the bottom, are going to cause you fits. Compost should be in bags, so easy-flow is possible. The EPM baskets are there to keep the bag of compost from twisting in the water flow, so the compost isn't constricted in that bag-basket design. But any other brewer with a basket has to have an aerator inside the basket, or the compost compacts, and goes anaerobic (happens at about 10 hours into the brew, so beware of the brewer that only has data for hours 0, 8, and 24)

Bubble sizes should be medium to large, not micro-sized.

Tiny, tiny bubbles are a bad idea. They shatter the fungal hyphae. Ask for the data showing good FUNGAL results. And please make sure the lab they are testing with uses decent methods.

No data? Don't buy the machine.

Only plate count data? Don't the machine. Ask what plate count data mean. Typically, you'll get gobble-de-gook as a reply. There are no data documenting a consistent relationship between plant growth and plate counts.

Compost teas that start aerobic, move into the anaerobic ranges, and because they are brewed long enough, return to aerobic fall into this category. They contain aerobic bacteria, and put-to-sleep anaerobic bacteria. Beneficial fungi, protozoa and nematodes have been pretty much destroyed by the anaerobic phase, although if the brew didn’t actually go anaerobic, then the beneficials may still be present.

These brews may contain some remnant anaerobic smells and materials. The diversity of food resources has clearly been increased, but the question remains what bacteria exactly were grown? Beneficials, or detrimentals? Disease-suppressors, or disease?

Disease-causing organisms often prefer, and grow better, in reduced oxygen condition. But if the brew went quite anaerobic, then the diseases were killed too. How low is low enough? When do the “bad guys” die, and when do the really bad guys, like Clostridium botulinum, start to grow? We don’t know.

What mix of foods results in the fermentative bacteria or fungi winning, versus the human pathogens? Is stirring vigorously at 12, or 16 hours going to select for the good guys enough to maintain the good guys? Or do you need to stir at 8, 12 and 24 hours? No one really knows. (If you do, please let me know, I’d like to see your data).

Most Biodynamic brews fit this LBCT definition, except Biodynamic preps do not always use compost. The preparations are plant teas, which means plant material is placed into water, stirred and the biology on the leaf surfaces grows using the sugars, proteins, carbohydrates, cellulose, and more recalcitrant (hard-to-decompose, quite complex and thus hard to attack) kinds of substrates.

Does that mean plant teas have no benefit? Of course NOT. If beneficial organisms are on the plant surfaces (and usually roots are included in the plant teas), the beneficial organisms will grow and increase in numbers or biomass during the brew cycle. Which good guys? It depends on the same factors as actively aerated compost depends – temperature, mixing, aeration, foods added, the age and stage of the plant (and therefore the actual foods added), etc.

But, in these LBCTs, no aeration other than occasional stirring is added. That means, if there are organisms present on the plant material, or in the compost if this is truly compost tea, the brew is very likely to go anaerobic for some period of time.

But for how long? And how low did oxygen go? And when did the growing organisms begin to run out of food, so that their oxygen use rate slowed? When did their metabolism slow down enough that oxygen began to diffuse back into the water faster than the organisms were using the oxygen?

By the end of a LBCT brew, the tea should no longer stink in any way, which means the tea has returned to the aerobic condition. The things that may kill your plant have been re-cycled back into bacteria biomass. Sorry, no fungi left in a brew that went anaerobic. The beneficial fungi are, for the most part, aerobic.

The time, or the conditions to allow conversion from aerobic to anaerobic and back again are not documented at all for these kinds of teas. That means that sometimes positive effects have been observed using these kinds of teas, but other times the teas have had no observable effect, and sometimes these teas kill plants. I’ve killed quite a number of plants using anaerobically produced tea, and while I have not published this data (it is hard to publish negative results), lack of publication does not mean it doesn’t happen.

That is why compost tea has been regarded as witchcraft, or voo-doo, or snake oil for all these years. The results have been too variable to make sense of what is going on. When sometimes great results occur, sometimes nothing, and sometimes really bad things happen, no one is inclined to put much trust in the results.

But, the Biodynamic approach controls many of the factors involved in tea making, IF THE PRACTIONER PAYS ATTENTION TO WHAT STEINER SAID. I’ve watched a number of biodynamic brews being made where part, or just about all of Steiner’s advice was ignored. If people don’t understand WHY something was required by science, they may ignore it. But then typically the results aren’t what you would want, or they do not give you the benefit you should be able to get.

The bottom line is, we need to put more effort into understanding these types of tea. But for now, until the work is done, either do what Steiner said, exactly, or use AACT. We are really getting a handle on how to guarantee that AACT is consistent, and beneficial, each time. Without an oxygen probe, and the time to monitor properly, FCT and LBCT remain of questionable benefit.

Soil Foodweb Inc performed a study of how do you know if compost tea will “work”?

The results (given below in Table 1). clearly show that plate counts are inappropriate for determining whether a compost tea will protect plant surfaces from disease. Direct determinations were excellent means of showing that tea can protect leaf surfaces from disease causing organisms.

Methods

Plants were obtained from a greenhouse where blight was causing a severe problem. All plants used were just beginning to show “burn” on the leaves from the disease.

Five of the plants were sprayed with Tea One, five plants sprayed with Tea Two. Control plants (water alone) and fungicide treated plants died within a week, as did the plants to which tea one (tea lacking suppressiveness, see table below) was applied.

Does the fact that plants sprayed with Compost Tea One died mean that compost tea does not work? No, because the plants sprayed with compost Tea Two (tea capable of suppressing disease in the table below) survived and grew well.

What was the difference in the teas? Tea Two, designated tea capable of suppressing disease in the tbale below, had high levels of active and total fungi, active and total bacteria, and good protozoan numbers. Application of these organisms to the plant foliage resulted in excellent coverage of the leaf surfaces. All of these plants lived.

Tea Two, designated tea lacking suppressiveness, did not contain adequate fungi, or fungal activity, and lacked the protozoa needed. While exactly the same amount of tea (or water, or fungicide on the control and fungicide-treated plants) was sprayed on all plants, Tea One did not have an adequate microbial population to protect the plant surface.

Plate methods could not differentiate between the two teas.

TSA incubated at room temperature, in aerobic conditions, measures “aerobic heterotrophs”. There was no detectable difference between the two teas using plate methods, despite the fact that Tea Two was capable of suppressing blight, while Tea One, sprayed at the same concentration, in the same conditions, did not suppress disease.

King’s B medium selects for pseudomonads, but not all these bacterial species are beneficial to plants. Enumeration indicated that there were more pseudomonads in the not-suppressive tea. Plate methods cannot distinguish whether the bacteria growing on this plate, and thus presumably pseudomonads, will be beneficial to the plant. If these values were used to measure “species richness-diversity”, the not-suppressive tea would get a higher “index” score than the tea that resulted in the plants remaining alive and producing a bumper crop of tomato later in the year.

Please note that “species richness-diversity” is not a valid name for any ecologically accepted measure of diversity. The lab that developed and uses this index will NOT explain how this index is calculated, and will not show any data that documents what relationship the index has with plant health. They claim the index is in any introductory textbook, but in fact, no textbook anywhere has a measure called species richness-diversity. Until such time as the lab using this index documents the claim that a higher index value actually means a benefit to the plant, the use of this index must remain highly questionable.

Spore-formers are determined by boiling the material in question to kill vegetative cells, followed by plating the material on TSA. Only spores or highly dormant stages of organisms survive boiling. Those spores capable of growing on TSA, at room temperature, in the particular oxygen conditions present in the plate (please recognize that oxygen exchange is reduced by the fact that the plates are covered), are then enumerated. Again, the not-suppressive tea had higher plate enumeration values. What is the relationship between what will grow on a plate, and physiological functions occurring in the soil, or on plant surfaces? These data show that there is no relationship.

Direct determinations separate bacteria from fungi. Plate media do not separate even bacteria from fungi, much less not giving an indication of what is going on with approximately 99.9% of the species present in the material plated.

Direct determinations also let you know whether protozoa or nematodes are present and performing their functions. A much clearer picture of what biology is present and performing their functions is possible when using direct determinations. Direct methods let you know if coverage on leaf surfaces is adequate. These types of assessments need to have a clear relation back to benefit to the plant.

Please note that there is no consistent relationship between plate count enumerations of “species richness-diversity” and improvement in plant growth. Plate counts do not assess diversity or activity of the organisms in the test material. An insignificant number of the actual total individuals or total species present in a sample grow on any single plate medium or set of lab conditions that it is difficult to see why anyone would continue to pretend that there is a relationship between plant growth and plate count assessments of diversity.

Desired levels of organisms (direct microscopy) in compost tea

• 10 to 150 or more µg active bacteria /ml compost tea
• 150 µg to 300 or more µg total bacteria /ml compost tea
  15,000 - 25,000 or more bacterial species (using molecular methods)
• 2 to 10 µg or more active fungi /ml compost tea
• 5 to 20 or more µg total fungal biomass/ml compost tea
  5,000 to 8,000 or more fungal species (using molecular methods)
• 2,000 or more protozoa
  1,000 or more flagellates
  1,000 or more amoebae
  10 – 30 ciliates. Higher numbers indicate anaerobic conditions resulting from organism in tea growing so fast that oxygen is consumed
• 2 to 10 BENEFICIAL nematodes/ ml (desired; typically lacking in tea)
  1 - 5 bacterial-feeders
  up to 5 fungal-feeders
  1 - 5 predatory nematodes (typically lacking in tea)
  No root-feeding nematodes
• Minimum of 10% active bacteria and fungi

With biology at or above these minimal ranges (more is better), this tea should result in improving foliar or soil life significantly, as long as pesticides, pollutants and dust are not a problem.

Application of a tea containing this set of organisms should result in a minimum of 65% of the leaf surfaces covered with bacterial biomass, and 5% with fungal biomass. In trial after trial, we have shown that with this minimum level of coverage, the leaf surface is protected, through a variety of mechanisms, from colonization by pathogenic organisms.

Compost Tea Standard Conditions

Some rumors flying out there suggest that someone is saying that there are no standard conditions for tea production, but in fact standard conditions are necessary in tea production.

In order to make consistent compost tea, the starting conditions must be t he same, and the same conditions must be maintained during the brewing.

We manage to routinely make teas with the same bacteria, fungal, protozoa and nematodes biomass and numbers present, time after time. But if you want something with a different set of organisms, or different levels of organisms, change the foods, the temperature of brewing, aeration, or water conditions. Maintaining the same conditions allow the same brew to be made over and over. Changing conditions allows a different tea to be made. Like making cake, or beer, biology responds to what you put into the starting mix and how you treat the material during the brewing, or cooking, process.

Standard conditions are:

1. room temperature water to begin,
2. no chlorine (aerate to de-gas)
3. neutral water (pH 6.5 to 7.5),
4. oxygen maintained above 6 ppm through the entire brewing cycle, and
5. good aerobic compost (per gram dry weight of compost) containing at least:

The list of papers specific to compost tea and compost have been summarized by Steve Diver, and are listed on the ATTRA website, www.ATTRA.org

Habitat requirements for beneficial bacteria and fungi required to prevent pests and pathogens

• Maintain 5.5 ppm O2 or higher during brewing cycle
• Pleasant Smell
• Increase in temperature of 1 to 10 F is normal
• Foam is typically sign of good bacterial metabolite development
• Maintain tea fully aerated as long as held before use

Testing Requirements

For new (untested) tea making machine:

• Compost quality (outlined above)
• Starting recipe of the tea
• Temperature, oxygen concentrations through the tea cycle
• Color of tea, foam, smell
• Chemistry and Pathogen testing must meet local standards (city, county, state, Federal).
• Organism assessments must be performed on three batches of tea
• Duration of the tests are 32 hours or until the growth of organisms in the tea is completed. This establishes the brewing cycle; extraction, growth, expected increase in organisms, duration of the tea cycle, when tea is ready to be used and whether the machine can hold tea for any length of time.

For existing machines with the above data available from the manufacturer:

• Type of tea maker used,
• Compost quality
• Starting recipe of the tea
• Temperature, oxygen concentration, and CO2 or O2 data through the cycle must be submitted for each of the first three batches of compost tea
• Chemistry and Pathogen testing must meet local standards (city, county, state, Federal).
• Initial three batches of tea must show three consistent sets of organisms produced at or above levels given above
• Once initial testing passed, each batch test each 3 months, or each set of different starting materials.

Sampling requirements for healthy foodweb assessment

• At end of desired brew cycle (depends on machine), measure temperature and CO2 or O2
• With the tea maker still circulating the tea, take at least 5 different 1 to 2 ounce or 30 to 60 ml samples and place them in a clean plastic 8 to 12 oz (100 to 500 ml) plastic bottle with sealable lid.
• Put the lid on the bottle, mix by shaking. If after mixing, the sample bottle is more than _ full, drain to halfway mark to allow airspace. The bottle should contain at least 125 ml (4 oz) of tea.
• Send overnight to SFI lab. Send with completely filled out sample submission form

C. 6. Tea Definitions

Compost Tea

• brewed water extract of compost,
• contains all the soluble nutrients that were in the compost,
• production methods include completely aerobic (AACT), using fermentative selective conditions (FCT), using long term brewing conditions where the tea returns to aerobic conditions after several weeks, as the smell goes away (LBCT), or using truly anaerobic conditions (NACT).
• A true compost tea should contain ALL of the organisms that are present in the compost. Loss of the aerobic groups when FCT, LBCT or NACT are made leaves it questionable whether these products should even be called compost tea. They lack a large component of the biology needed to obtain the benefits that are possible from compost or compost tea.

Put-to-sleep teas

• the organisms in the tea are put-to-sleep using a long-brewing time, or through use of a chemical that makes the organisms minimize activity. Unfortunately, the putting-to-sleep process invariably kills many, many species. When we have documented these processes, in general, species diversity is reduced by 50% during the putting-to-sleep process.
• SFI has worked with a recent process where organism diversity has not been impacted, so it may be possible to not have reductions occur

Compost Extract

• no brewing time water extract of compost. This is just the organisms, as is, from the compost. No growing time allowed.
• Soluble nutrients, enzymes, hormones and plant growth compounds are very much present. It does not take long for the enzymes, hormones or plant growth compounds to be taken up and consumed by bacteria or fungi in these materials, however.

Compost Leachate

• extraction of the organisms is minimal, so that this material is almost strictly the soluble nutrients that were in the compost. Because of the minimal amount of biology in this material, these enzymes, proteins, hormones and other materials do not disappear as rapidly as in a compost extract.

Plant tea

• compost is not involved. May have good organisms present in the tea, if beneficials were present on t he plant surfaces.

Manure tea

• compost is not involved. Typically a concern will be present about human pathogen load present in the material. Some documentation says that adequate aeration, WITH the right biology and activity of that biological compoenent, can reduce the human pathogen load. More testing is required.
• Manure teas should not be used on human foodstuffs any sooner than 90 to 120 days before harvest.

• 5 gallons per ac (25 L per HA) for each 6 foot of canopy

• 20 gal per ac (100 L/ HA) each spring and fall,
• Or combine with compost application in the fall, tea soil drench in the spring

• spray into seed surfaces in a light mist, not even enough to wet the seeds significantly
• roll seed or seed piece in solution of tea
• place a drench of tea below seed as planting in furrow

• remove soil core and spray tea into the aeration hole
• re-fill the aeration core with compost – compost tea - sand mix

C. 8. Programs for Converting to Biological Farming

C. 8. Programs for Converting to Biological Farming

Shifting from Chemical Intensive Practices to Sustainable Practices:
"How to's" of corn, wheat and soybean systems in the mid-west

Dr. Ingham is happy to discuss these scenarios by e-mail with people, and alter these specific approaches to fit their particular systems.
info@soilfoodweb.com

Irrigated Wheat

Irrigated Corn

Irrigated Soybeans

C. 9. USGS Maximum Dissolved Oxygen in Water table

DO - % saturation

Oxygen saturation is calculated as the percentage of dissolved O2 concentration relative to that when completely saturated at the temperature of the measurement depth. Recall that as temperature increases, the concentration at 100% saturation decreases. The elevation of the lake, the barometric pressure, and the salinity of the water also affect this saturation value but to a lesser extent. In most lakes, the effect of dissolved solutes (salinity) is negligible; but the elevation effect due to decreased partial pressure of oxygen in the atmosphere as you go up (recall the breathing difficulties faced by Mt. Everest climbers) is about 4% per 300 meters (1000 feet). The DO concentration for 100% air saturated water at sea level is 8.6 mg O2/L at 25°C (77°F) and increases to 14.6 mg O2/L at 0°C.

Table 6.2–6. Solubility of oxygen in water at various temperatures and pressures [From R.F. Weiss (1970). Temp °C, temperature in degrees Celsius; atmospheric pressures from 695 to 600 millimeters mercury begin after 40°C] (PDF) link to table