Compost Teas: Microbial Hygiene and Quality In Relation to Method of Preparation

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COMPOST TEAS: MICROBIAL HYGIENE AND QUALITY IN RELATION TO METHOD OF PREPARATION

SUMMER, 2004

mixes from composts (Brinton and Tresemer ).Weltzien is no stranger to the U.S. and has been a frequentvisitor in the Dakotas where he and his wife have workedon projects with Native Americans. Somewhere in thistime frame is possibly when the American developmentswith compost extracts began. Weltzien and his colleaguesand numerous German doctoral candidates, have presented

a variety of ndings in publications and journals worldwidesince that time (see Weltzien list in references).

The changes and in many cases apparent distortions of Weltzien’s early work that took place since then in the U.S.are difcult to trace clearly. These changes led ultimately toa crisis point this past year with the formation of a nationalTask Force convened under the direction of the USDA,called the NOSB Task Force on Compost Teas, whose re-port recently appeared (USDA-GOV ). Reports of odorous teas, teas apparently containing E. coli,and gen-eral public concern about risk of contamination of foodcrops by live bacterial cultures, were the root causes for the

formation of the Task Force. Several investigations of com-post teas were undertaken in a short period (Bess et al

; Duffy et al ; Millner et al. ). These studiesand our own reported herein were mostly conducted to de-termine whether compost teas could be unsafe in terms of bacteriologic risks, especially as regards E. coli . Clearly theearly work of Weltzien and our own work with Tränknerfocused on efcacy studies in the eld with varying croppathogen systems; in other words, showing how and underwhat circumstances quality composts could be prepared andused to control plant fungal diseases. The current situationlargely eclipses this benecial approach with bacterial con-cerns. This is not surprising, since the concerns about food-borne bacterial poisoning have forced themselves into theforefront, and are likely to be with us for some time (Meadet al. ). Organic and biodynamic growers who usethese practices must now exert new attention toward hy-gienic management and potential consumer impact.

One of the reasons to perform an independent composttea study was to attempt to discern if the more recent em-phasis in the US on mechanically aerated, “brewed” teas hadany advantages. The proponents of these new approachesadvocate, among other actions, a drastic shortening of the

European approach to the brew phase to as little as twelveto twenty-four hours, which seems more convenient, plusthe addition of molasses and other adjuvants to enhance andraise bacterial counts to very high levels, which might re-sult in more disease control. Further, some of these ap-proaches emphasize various ratios of microbes in the brews,allegedly based on the concept of improving biodiversity of soils and treated plant surfaces.

A drawback to these new approaches is the apparentbacklash against traditional European methods. Workerswho had focused for years on the scientic, yet eld-orientedEuropean approaches to brewing teas found that thesemethods were suddenly being labeled “anaerobic” in theU.S. or that the teas thus produced possessed incorrect“bacterial-fungal ratios”, a topic rarely if ever discussed in

the original German research, and also not supported by sci-entic literature in the U.S. Had something been over-looked? Were some teas now dangerous? Or was this sim-ilar to the debate regarding aerobic versus anaerobiccomposting that spread across America in the late s andearly s. In that school of thought, proper “aerobic”composts were felt to require the turning of piles as oftenas three times a day, up to thirty times in the life of a com-post pile. Any grower not so doing was held to have a con-dition that was “anaerobic.” This controversy led in part toseveral studies on pile turning versus compost quality. TheUSDA funded one such study, and an excerpt of it was pub-

lished in this journal (Brinton ). There was no scien-tic basis to conclude that the enhanced turning promotedan extra aerobic state or signicantly improved compostquality – in fact, more turning resulted in signicantly in-creased losses of nitrogen and organic matter. A similarstudy supported by Agriculture Canada reached the sameconclusions (Jobin et al ). Thus, the research team feltthere was a chance that we would not be able to support sci-entically the new claims and charges being made with thenew tea methods.

In our compost tea project we partly wished to comparethe European versus the newer US approach, and further,to conrm if E. coli could become a problem in either orboth systems. Our work with compost indicated that manyimmature composts are available on the market, with littleor no quality testing behind them. We wanted to comparethe European approach, in which mature compost is steepedin a barrel of water with gentle stirring over days, to mod-ern technological approaches involving mechanical extrac-tors and added agents as provided by “tea equipment com-panies.” The attraction of the latter is that anyone can buya piece of equipment along with the compost and the in-oculant to make suitable compost tea. One participant in

our study team represented a large national distributor of garden care products. Their view was that once someonebought such equipment (which possibly their companywould sell), then they most likely would revert to using theirown composts and additives rather than keep buying theneeded ingredients. Thus, we also wanted to test these pur-chased compost units by substituting our own farm-madecompost, with and without using the commercial additives.



3REPRINT: BIODYNAMICS

We split tea production so that an independent party wasalso manufacturing the teas for our study using instructionsprovided with the equipment.

The resulting objective in this tea study focused mostlyon convenience and consumer safety. Unfortunately,whether the tea produced is efcacious or not against plantdisease was not evaluated. We would refer readers to the

many published papers and grower reports, to get a senseof the practice and results.

To summarize, in this study our goals were:a) to evaluate whether two of the commercially available

compost tea brewing systems could present a poten-tial pathogen risk to consumers when using them athome as directed, and as modied by using compostreadily at hand;

b) to measure normal and expected bacterial (includingE. coli ) and fungal growth and die-off in various teasby monitoring aerobic plate counts, anaerobic platecounts and fungal plate counts in the commercial and

other teas;c) to compare the effects of mechanical aeration (com-

mercial systems) or lack of aeration (“European” sys-tem) on the four microbiological parameters listedabove and upon the actual percentage of dissolved oxy-gen in the tea.

For the study a commercial research strain of E. coli (American Type Culture Collection source) was used as thesource for inoculated indicator organisms, as a test for pos-sible pathogen reproduction. The most probable number(MPN) of E. coli at zero hours, twenty-four hours and sev-enty-two hours was studied in the assembled teas and theiringredients (compost and nutrient additives), and the waterused in their formulation. We also conducted side testsmaking comfrey teas indoors and outdoors, as is practicedin gardening. We also see the need to perform future testsfor biodynamic preparation , which may be considereda form of “compost tea” and also the similar horn-manureextracts.

Materials and methodsTea Preparation ( A-F)

A-Two commercial tea extraction units (“ s - ” and “ s - ”) were

provided by the manufacturers for the project, and were rep-resented as current, best-available technology as of June ,. The units were set up for compost tea extractions ac-

cording to product directions provided with the equip-ment. Both commercial products provide with the unit astandard compost (unknown source) plus a “nutrient”source that is added when the compost is placed into theunit with water. One manufacturer included a newer

nutrient formulation that lacks molasses (This modicationwas presumably based on recent information, because theuse of molasses is now understood to promote excessivelyrapid colonization of possibly pathenogenic microorganismsin brews). Both units are designed to provide constant bub-bling aeration for up to twenty-four hours, employing dif-fering modes of action. One unit sucks air from the top and

expresses it into the solution through a central rapid-whirling mixer; the other unit forces air to the bottom of the unit and bubbles it upward via holes in a circular ring.B: In addition to commercial units, a European method was

established based on Brinton’s review of prevailing practice(Brinton Report to Compost Tea Task Force ). Thisemployed no additives other than stable compost, and wasprepared without aeration equipment by once daily stirringin loosely covered vessels.C: Time- sub-samples of each compost tea were taken

immediately after the start of the trial by on-site samplingof the slurry into sterile containers, which were immediately

refrigerated. At twenty-four hours, the teas were all resam-pled (Time- samples) and together with the refrigeratedTime- sample, taken into the lab and microbiologicaltests commenced immediately. At forty-eight hours (orseventy-two hours from set-up), the laboratory staff re-sampled and analyzed the remaining tea, which had beenstored, loosely covered, at room temperature in the lab. Thepurpose of this was to assess degradation after terminationof aeration. Aeration of these teas only occurred during therst twenty-four hours after their preparation.D: The same set-up and handling processes were repeated

the following week after inoculating the teas on-site at dayzero with ml 8 E. coli in TSB (made to the turbidity of

. McFarland standard).E: The following week, a third trial was initiated as before,for the two s - and s - units, by substituting an immaturecompost from Woods End lab’s recent archive instead of thecompost that was shipped with the product. This was topartly fulll objective (b) of our stated goal, i.e., to evalu-ate a scenario in which a homeowner would use their owncompost instead of constantly re-purchasing the compostplus nutrients from the manufacturers of the tea equipment.F: In the lab, ve European-style compost teas were set

using a : (volume) water to compost proportion (one wasactually comfrey tea). Three composts were mature and twowere immature (using the Solvita®Maturity Test rank-ing)(Changa et al. ). One-gallon batches were pre-pared. As noted in (b) above the European method uses nei-ther supplemental aeration nor added nutrients, but doesinvolve stirring once each day.G: In the lab, the nutrients and the composts for s and s



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SUMMER, 2004

were mixed separately with sterile Phosphate Buffered Waterin the same ratio as the compost teas. These were also an-alyzed separately after zero, forty-eight, and seventy-twohours.H: The on-site water and the laboratory water, as well as theimmature composts and the mature composts, were all ini-tially tested for the presence of E.coli .

Microbiological Tests: Sample-groups A-E above were analyzed for:

) E. coli using tube MPN at dilutions - – - start-ing with LST Broth and nishing with EC+MUGBroth as in Standard Methods # F.

) Aerobic bacterial levels (Aerobic Plate Count) usingpour plates at ve serial dilutions (with PhosphateBuffered Water) ranging from - to - with StandardPlate Count Agar (Difco) and incubated at C forforty-eight hours.

) Anaerobic bacterial levels (Anaerobic Plate Count)

using pour plates at ve serial dilutions with Phos-phate Buffered Water ranging from - to - withAnaerobic Agar (Difco) incubated at C for forty-eight hours in anaerobic chambers using OxoidAnaerobic Indicators and MGC AnaeroPack-Anaeroto guarantee and monitor lack of oxygen.

) Total viable fungi – including yeast (Fungal PlateCount) – using pour plates at serial dilutions withPhosphate Buffered Water ranging from - to - ,made with Malt Extract Agar (Sigma) with addedStreptomycin sulfate ( mg/L MEA) incubated at

C for hours. For samples that received addedE. coli,the bacterial levels sometimes exceeded theability of the Streptomycin to inhibit them. This cre-ated the possibility that fungal plate counts similar toaerobic plate counts might be reecting the E.coli and not yeasts.

Sample group F was only tested for E.coli . A three-tubethree-row MPN was set using the same media (doublestrength in row ) as in No. ( ) above.

Results About presence of E. coli in test samples

Escherichia coli is the bacterium commonly used to indicatefecal contamination of soil, water, and so on. It is one smallstrain within the group of “fecal coliform” bacteria. Of themembers of this group, E. coli is “more indicative of recentfecal contamination and unsanitary processing in food thanthe whole fecal coliform group.” (FDA/CFSAN BAM O n-line September )

Since E. coli does represent a large part of the normal and

necessary bacteria in the intestines of all birds and mammals,when it is found in foods or water or compost tea it sug-gests contact between fecal matter and those materials. Thecontact could have been direct, as in animal manure, or in-direct – as from soiled human hands. Microorganisms thatalso inhabit the intestines cause many human diseases;hence, the presence of E. coli indicates the possible presence

of any or all of those pathogens. E.coli can be (but usuallyisn’t) a pathogen; certain strains or varieties of E.coli do causevery serious diarrhea, kidney failure, blood infections, blad-der infections and more. These varieties dwell in theintestines along with the non-threatening E. coli . Further-more, E. coli presence correlates closely with other pathogensand pathogen indicators such as fecal streptococcus, E. col

-h , and Clostridium perfringens (Brinton ).

General Findings No E. coli was found in the two complete unamendedcommercial compost teas, their components, or in the

European tea at time- . There was no increase of E colduring twenty-four hours of aeration, and none after, whenaerators were halted thirty-six additional hours (see Table

on page ).However, both the commercial teas, and their compo-

nents, when “spiked” with E.coli,were clearly able to sup-port the growth of E. coli . In one method the E. coli countdeclined after the aerator was turned off. This is also seenin later trials.

Both total aerobic and anaerobic bacteria counts in-creased during extraction with the mechanical aerator units,and aerobic bacteria increased in the European methodwithout mechanical aeration. The ratio of aerobic to anaer-obic bacteria declined over time in the s and s aerationbatches and increased signicantly in the European methodsamples. In Unit s , aerobic bacteria increased dramaticallyafter the unit was turned off. Fungi increased too overtime. E coli added to the European method had declinedby seventy-two hours. These data suggest that simple ex-planations as are common in the popular press do not aidus in understanding what is happening; they certainly alsocontradict the notion that by not stirring a tea it automat-ically goes “anaerobic.”

In Table (page ), we show commercial tea units inwhich we substituted immature compost for the compostthat is shipped with the units. This handling would satisfyour objective (a) in the introduction, where an individualwould use his or her own composts to make tea. As seen inTable , these treatments appeared to suppress E. coli growthwithin seventy-two hours, even after aeration was stoppedat twenty-four hours. In this particular immature compost,



5BIODYNAMICS

AnalysisTest – time in hours

S-1 machine method S-2 machine method European methodas is with E. coli as is with E. coli as is with E. coli

E. coli MPN 02472

Aerobic PC 0

2472

Anaerobic PC 02472

Total fungi 02472

<3<3<3

4.20E + 09

2.20E + 105.50E + 091.40E + 056.40E + 073.60E + 073.30E + 035.40E + 051.20E + 05

>11,000>11,000

7.41.30E + 10

6.80E + 091.00E + 061.50E + 095.00E + 071.00E + 053.50E + 091.60E + 117.00E + 04

<3<3<3

6.00E + 05

5.80E + 062.80E + 124.00E + 021.50E + 042.00E + 113.00E + 021.30E + 031.60E + 05

>11,000>11,000

7.4>1.5E + 12

1.5E + 12>1.5E + 122.20E + 093.60E + 09

NA2.20E + 094.40E + 094.00E + 11

<3<3<3

6.60E + 05

5.50E + 096.00E + 115.00E + 053.30E + 032.50E + 043.30E + 039.00E + 021.80E + 03

240NA4

1.20E + 12

NANA

1.20E + 12NANA

1.20E + 05NANA

Table 1. Microbiological traits of aerated and European technology teas

AnalysisMPN or CFU/ml

S-1 food + unripe compost S-2 machine methodas is E. coli added as is E. coli added

E. coli MPN 02472

Aerobic PC 02472

Anaerobic PC 02472

Aerobic:anaerobic ratio 02472

Total fungi 02472

210075093

8.60E + 122.40E + 101.56E + 062.00E + 091.00E + 071.60E + 054.30E + 032.40E + 031.00E + 019.00E + 112.50E + 071.70E + 07

>11,000>11,000

7.41.30E + 106.80E + 091.00E + 061.50E + 095.00E + 071.00E + 053.50E + 091.60E + 117.00E + 042.70E + 05

NANA

<3<3<3

6.00E + 055.80E + 062.80E + 124.00E + 021.50E + 042.00E + 113.00E + 021.30E + 031.60E + 056.00E + 041.80E + 11

NA

>11,000>11,000

7.4>1.5E + 121.5E + 12

>1.5E + 122.20E + 093.60E + 09

NA2.20E + 094.40E + 094.00E + 118.00E + 02

NANA

Table 2. Compost tea units with immature composts

Note: designations such as 1.00E + 07 mean 1 x 10 7.

the initial tests showed < MPN E. coli per gram wet weight.However, when added to the compost to make tea, the E.coli was able to grow. The most likely explanation has to do withsampling from the compost source relative to sample het-

erogeneity.In Table (page ) we show a similar scenario, but thistime the commercial compost tea units are run with onlythe compost provided with the unit as sold, and no nutri-ent inoculation. These results showed that both compostsprovided had no measurable E. coli . In fact, the added E.coli died off after seventy-two hours in these teas (eventhough the aeration units were turned off after twenty-four

hours). Note that we added no molasses or other inoculumto these batches.

One of the composts – s – had signicantly more fungithan bacteria when the tea was set up, but the amounts of

fungi diminished steadily thereafter. Both compost teasgave signicantly more aerobic bacteria counts after threedays standing than after twenty-four hours of mechanicalextraction. These and other results support the Europeanview that longer extractions give better performance; indeed,in Weltzien and Tränkner’s work, better disease controlalmost always resulted from the longer brewed teas.

In Table (page ),we show the nutrient source only,



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SUMMER, 2004

Test trait hours brew S-1 food + unripe compost S-2 machine methodas is with E. coli as is with E. coli

E. coli MPN 02472

Aerobic PC 0

(mpn/ml) 2472

Anaerobic PC 0(mpn/ml) 24

72Aerobic:anaerobic ratio 0

2472

Total fungi 0(mpn/ml) 24

72

<3<3<3

2.10E + 09

NA2.20E + 073.40E + 03

NA9.00E + 026.2E + 05

NA2.40E + 069.00E + 023.10E + 031.00E + 03

2.40E + 03>11,000

NA7.80E + 10

NANA

7.20E + 07NANA

1.00E + 00NANA

3.10E + 03NANA

NA<3<3

6.00E + 05

NA2.50E + 112.00E + 02

NA7.80E + 033.00E + 03

NA3.20E + 092.00E + 021.20E + 031.80E + 03

NA2.40E + 02

NA5.6E + 11

NANA

3.50E + 07NANA

1.60E + 04NANA

9.00E + 02NANA

Table 3. Aerator technology compost only w/o nutrients

Test trait hours brew S-1 food + unripe compost S-2 machine methodas is with E. coli as is with E. coli

E. coli MPN 02472

Aerobic PC 0(cfu/ml) 24

72Anaerobic PC 0(cfu/ml) 24

72

<3<3<3

1.00E + 02NA

<1001.00E + 02

NA

<100

NA>11,000>11,000

NANANANANA

NA

<3NA<3

<100NA

2.90E + 081.00E + 02

NA

9.00E + 03

NA>11,000>11,000

NANANANANA

NA

Table 4. Commercial tea unit, nutrient source only

which is the food-inoculum provided with the two com-mercial units. There were relatively low counts of bacteria,especially in the s units, and in the s some more grew, es-pecially later (after the aerators were turned off). In anyevent, E. coli certainly did not die off after being added –indeed these inocula may have favored their growth, com-pared to the die-off seen in Table .

A similar result is seen in that there is no evident E. coli

in the standard compost, but with inoculation, the E. coli grew readily, at least in unit s . Results were inconclusivein s .

The European-style teas, which were made with maturecompost known to contain some E. coli,also appeared toinhibit the growth of that E. coli.European-style teas madewith immature composts also reduced the E. coli levelsover time. Perhaps the absence of a readily available carbon

substrate (i.e., no molasses) and the absence of active aer-ation provided harsher survival circumstances for E. colreplication. It is a very common error in literature on com-post teas that “aerated teas” are thought to be “free of po-tential pathogens.” This would only be true in the case of obligate anaerobes, such a Clostridiaspp., whereas E. coli incontrast is readily cultured under aerobic conditions.

In Table , we observe our results with comfrey tea. The

extract was prepared using a common organic gardeningformula of a : fresh-weight:water mixture. This was rstprepared outdoors in a -liter open-top container, withdaily stirring. This tea was thus exposed to the environmentin an area populated by birds and subjected to frequenthuman handling. The solution smelled very bad. Whentested, this comfrey tea understandably had very high lev-els of E.coli . However, when the same tea was prepared in

REPRINT



7BIODYNAMICS

Analysis hours brew outdoors in labE. coli 0mpn/ml 72

1207200

Aerobic 0(cfu/ml) 72

1207200

Anaerobic 0(cfu/ml) 72

1202400

Aerobic:anaerobic ratio 072

1207200

Total fungi/ml 072

1207200

NANANA

>110000

NANANA

4E + 12NANANA

4.40E + 11NANANA9.1NANANA

1.30E + 02

<3<3<3NA

1.10E + 05>2.40E + 12>1.80E + 12

NA1.60E + 036.50E + 12

>2.20E + 12NA693.7

8200NA

3.00E + 025.10E + 115.70E + 08

NA

Table 5. Comfrey tea prepared w/o mechanical aeratoroutdoors and in lab

the lab under more controlled conditions – using freshharvested but un-washed leaves, touched only by sterile im-plements and made with well water (tested to be E. coli -free), and kept loosely covered – it showed absolutely nomeasurable E. coli over hours. Both aerobic and anaer-obic plate counts continued to rise over time in the labo-ratory extracted samples, without aeration. This indicatesclearly that some simple practices in hygienic handling(washing tools before use, using clean water and providingprotection from birds over-ying the tanks!) may be veryhelpful in enabling growers to prepare safe extracts.

In Table (page ), we show the European method re-peated for two mature composts and one immature com-post. Mature composts were Solvita – and immature,where used, were < . E. coli counts in the mature composts,which were low and declined steadily during the tea prepa-ration process. In the immature compost, E. coli was slightly

higher, but also declined during the tea preparation, withstirring once per day. Thus we see no evidence that the orig-inal Weltzien-type approach to preparing tea extracts withreduced technology is anaerobic or leads to reproductionof pathogens.

It is clear from these ndings that aerobic bacteria countsin the teas are variable but mostly very high, and increaseor decrease slightly over time. Furthermore, the ratio of

aerobic to anaerobic microbes is high to extremely highthroughout. There is no evidence therefore of an increasein anaerobic activity. Finally, all these teas were odorless.

DiscussionThe ultimate goal of this and other efforts is to have no E.coli present in compost teas. The newly recommended

USDA-NO P standard is that teas shall possess no more thancfu/ ml of E. coli or no more than cfu/ ml of

enterococci . Clearly, it is intended that compost teas will beapplied to food plants, including those that may be con-sumed without thorough washing. According to this in-vestigation, if a small amount of E. coli is introduced intoa tea, its population levels will decrease to the point of ex-tinction in – hours. It is possible therefore that short-term brews, with added sugars, may in fact have representedone of the least safe practices. New concern about this hascaused tea makers to start withdrawing at least molassesfrom their brews (personal communication, Bob Cantisano,

). Avoiding the introduction of unwanted microbesinto tea is obviously the best approach. Our expectationof a large and continuing increase of E.coli populations inteas was not validated by evidence in the study, and onlywhen large amounts of E.coli were added to the teas, did thelevels remain high. These results were independent of thepresence or absence of aeration.

Aerobic Bacterial Levels.High levels of aerobic bacteria ( - per ml) apparentlyendow fungal disease resistance to plants. This may be dueto their ability to metabolize unusable molecules into formsthat plants can absorb and assimilate. Boehm and Hoitink ( ) have argued that one must have sustained high mi-crobial activity to confer disease control from composts, butthey were not dealing with compost teas. Some more recentstudies rened this view. They show that the disease sup-pression was only high at the beginning of the period of highmicrobial activity and that the species of bacteria do change,strongly suggesting that a particular group of bacteria caus-ing the suppression is replaced by others in succession.This would mean that “lots of bacteria” aren’t enough overtime to maintain disease control. The expectation in the

compost tea work was that the APC (aerobic plate count)would rise until either the oxygenation was stopped or thenutrient supply became low. The more rapid the rise inAPC the more rapidly the fall would begin. Our data dosupport this prediction, although not overwhelmingly.Without active aeration, APC in the European method teaswas predicted to increase more slowly than in the other teas;however, this was also not the case. It may be some time be-



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fore these relationships are understood and we have a clearsense which microbes and/or what set of factors is confer-ring control. Considering the complexity of the subject, aholistic expectation is appropriate. Certainly the impressionone gains from the popular press that the means to makecompost teas is all worked out and accessible through sim-ple formulas or recipes, is not supported by any practicalor scientic results.

Anaerobic Bacterial Levels The anaerobic bacteria are generally considered to be un-desirable: some produce objectionable odors that are alsophytotoxic and others convert plant-nutrients into unusablecompounds. However, anaerobes are not strictly reliant onxed regimes; facultative organisms that can survive aero-bic and anaerobic conditions are prominent in nature.

Because of the low solubility of oxygen in water, the Eu-ropean teas would be expected to become a suitable anaer-obic environment. However, without active aeration, theseEuropean teas did not develop large anaerobic bacterialcounts as predicted. Even the teas allowed to steep forhours did not support a large anaerobic population, or one

that appeared appreciably different to the mechanicallyaerated teas.It should be pointed out that the relative insolubility of

oxygen in water ( . – . mg/L water at °C) prevents morethan a minimum amount from dissolving, whether aeratedor not. This same solubility factor may prevent the oxygenconcentrations from plunging low enough to allow the ob-ligate anaerobes to reproduce (some require as low as < .

mg/L air). Certainly the concept of physically frothing thewater with high tech equipment, analogous to the early

s approach of beating composts continually to aid aer-ation, is inappropriate. Only so much oxygen will be ab-sorbed, while the rest is thrown off. Growers who do not usethe high tech approaches, therefore, need not feel that their sim-ple approaches are incorrect. However, more care and cautionwith regard to hygiene is denitely in order. More chemistryand physics knowledge is needed to unravel the relation-ships of equipment and handling to hygiene and quality.

Total Viable Fungi Certain fungi repress the growth of other fungi that parasitizeplants. Other fungi are desired for their ability to degradeorganic compounds into forms bacteria can use. It is mostlikely a favorable thing to have consistent levels of fungi incompost teas. This study however did not attempt to pur-sue fungal investigations to any particular extent, but onlyto observe levels as inuenced by the various technologies andtreatments.

We observed fungal stability in the teas throughout theirrecommended use time. The total numbers of fungi appear

to go into some decline at seventy-two hours in the aeratedteas but not the European teas. More work will have to bedone to understand these inuences.

ConclusionsThis study represents a preliminary look at bacterial andfungal parameters in some compost teas prepared using twodifferent technologies: two commercial brewing systems

Strain hours brewEuro mature–B

cfu/mlEuro mature–C

cfu/mlE. coli 0

72120

Aerobes 0

72120

Anaerobes 072

120Aerobic:anaerobic ratio 0

72120

Total fungi 072

120

7<3<3

1.90E + 09

4.60E + 123.10E + 094.60E + 034.00E + 021.00E + 014.10E + 051.20E + 093.10E + 084.10E + 051.20E + 073.10E + 09

433

2.40E + 11

>1.40E + 128.00E + 081.20E + 052.00E + 032.80E + 032.20E + 067.00E + 112.90E + 051.60E + 031.00E + 021.00E + 02

Euro immature–Bcfu/ml

940942

2.60E + 05

9.40E + 076.80E + 078.00E + 046.60E + 032.00E + 023.20E + 001.40E + 053.40E + 054.00E + 001.40E + 033.40E + 05

Table 6. European method teas with various composts



9BIODYNAMICS

both based on differing forms of mechanical aeration ap-plied to a compost/nutrient solution and ve compost/watermixtures with brief daily stirring. The study sought to seehow E. coli population size would behave in these teas, andobserve how great an impact mechanical aeration makes onthe bacterial character of a compost tea.

a) The two commercial systems did produce E. coli -free

teas.b) The two commercial systems, and their isolated in-

gredients, when inoculated with E. coli,did supportits growth.

c) E. coli should be prevented access to all compost teasby ( ) clean handling techniques and ( ) using com-posts that have no tested E. coli (very mature, no newmanures, no exposure to fecal matter during storage).

d) At least for small-scale tea brewing, there seems to beequal growth of desirable microbes in both aeratedand non-aerated systems.

Based on this, we believe there may be some misunder-

standing about aeration of compost teas and about whatconstitute anaerobic conditions. Furthermore, we see nocompelling evidence here that aerator equipment makes anycontribution whatsoever to the making of – gallon( – liter) batches of compost tea, as long as the com-post is of reasonable quality. However, since growers maymake teas outdoors, in improperly cleaned containers, orwhere animals and birds may have access, and exposure todusts may occur, there may be increased opportunity forcontamination. It is urged that growers and compostersfocus attention on the compost quality and hygienic cir-cumstances surrounding their manufacture, while the ac-tual form of technology may be of less signicance.

Finally, in a certain sense, our study reveals, historicallyspeaking, how a variety of early events shaped a new crisisthat in turn is leading to new and improved understand-ings. Early concepts and popular misconceptions aboutmicrobes and aeration, plus the rapid adaptation of “brewthinking” in terms of how to grow as much bacteria asrapidly as possible, explains what many have come to regardnow as a form of self-fullling prophecy. A very zealous earlyapproach to enhanced brewing led among other things tovery odorous teas (due especially to use of molasses and

other additives), and culminated in the invention of tea ex-traction equipment designed to help x the aerobic prob-lem. Thus, the compost tea eld in America has had an ac-cidental and discontinuous development course. Perhapsmuch of the confusion could have been avoided if some at-tention had been paid to the wealth of previously publishedliterature and if more cross-pollination had occurred be-tween present-day producers and earlier practitioners.

ReferencesBess, V. H., R. B. S. Manes, and J. L. Snodgrass. E. coli survival

in compost tea using different nutrient substrates. Proceedings 2002International Symposium Composting and Compost Utilization.

Boehm, M.J., and Hoitink, H.A.J. . Sustenance of microbial ac-tivity in potting mixes and its impact on severity of Pythiumrootrot of Pointsettia. Phytopathology : ‒ .

Boehm, M.J, Tianyun Wu, Alex G. Stone, Bart Kraakman, DonnaA. Iannotti, G. Edwin Wilson, Laurence V. Madden, and HarryA. Hoitink. . Cross-polarized magic-angle spinning c nu-clear magnetic resonance spectroscopic characterization of soil or-ganic matter relative to culturable bacterial species compositionand sustained biological control of Pythiumroot rot. Applied and Environmental Microbiology : ‒ .

Brinton, W. . The control of plant pathogenic fungi by use of compost teas. BIODYNAMICS : ‒.

———. . Sustainability of Modern Composting: Intensicationversus Costs and Quality. BIODYNAMICS : ‒

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products. Proceedings,World Congress on Hygiene of OrganicFarming. Michigan State University, March .

Brinton, W.F, A. Tränkner, M. Droffner. . Investigations into liq-uid compost extracts. Biocycle , no. : ‒ .

Brinton W. and D. Tresemer. . Organic growing media: use of compost for potting mixes. Proceedings,IFOAM, Santa Cruz

Changa, C.M , P. Wang , M.E. Watson, H.A.J. Hoitink, and F.C.Michel Jr. . Assessment of the reliability of a commercial ma-turity test kit for compost. Compost Science & Utilization, no.: ‒ .

Duffy, B., C. Sarreal, R. Subbarao, and L. Stanker. . Effect of mo-lasses on regrowth of E. coli O :H and Salmonellain compostteas. Compost Science and Utilization( ): ‒ .

Jobin, P., J. Petit, C. Bilodeau, and W. Brinton. . Evaluation de differents systems de compostage de fumier a la ferme.Ministère deL’Agriculture du Québec. (MAPAQ)

Mead, P.S., L. Slutsker, V. Dietz, L.F. McCaig, J.S. Bresee, C. Shapiro,P.M. Grifn, and R.V. Tauxe. . Food-related illness and deathin the United States. Emerging Infectious Diseases : ‒ .

Millner, P., D. Ingram, W. Brinton, and P. Storms. . Composttea microbial safety issues: information and data summary. Un-published manuscript, USDA-ARS-SMSL and WERL.

USDA-GOV. . Report of the Compost Tea Task Force . At

<http://www.ams.usda.gov/nop>Weitzien, H.C. . Untersuchungen über die Ursachen der Keim-hemmung von Pilzsporen im Boden. Zbl. Bakt. Parasit. Infekt.Hyg. : ‒ .

———. . The effects of compost extracts on plant health. In: P.Allen and D. Van Dusen, “Global perspectives on agroecology andsustainable agricultural systems.” Proc. 6. IFOAM-Meeting :

‒ . Publ. Univ. of Calif., Santa Cruz.



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SUMMER, 2004- Reprinted from Journal of Biodynamics Vol.2:36-45

———. . Some effects of composted organic materials on planthealth. Agriculture, Ecosystems and Environment : – .

———. a. Advances in biological control of fungal leaf pathogensthrough fermented organic substances and microorganisms. In:J.E. Cassida, Pesticides and Alternatives.– . Elsevier SciencePublishers.

———. b. The use of composted materials for leaf disease sup-

pression in eld crops. BCPC Mono. , Organic and Low Input Agriculture. – .

———. c. Neue Forschungen zum Thema “Kompost und Panzengesundheit.” . H ochschultagung der Landwirstschaftl.Fakultät der Univ. Bonn. – .

———. . Biocontrol of foliar fungal diseases with compost ex-tracts. In: J.H. Andrews, S. Hirano, Microbial Ecology of Leaves,.Brock Springer Series in Contemporary Bioscience, BSBN

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Weitzien, H.C., and N. Ketterer. a. Control of downy mildew,Plasmopara viticola(DE BARY) BERLESE et de TONI, ongrapevine leaves through water extracts of composted organicwastes. J. Phytopathol. : – .

———. b. Control of Phytophthora infestans on tomato leavesand potato tubers through water extracts of composted organicwastes. Phytopathol. : , Abstract .

Weltzien, H.C. and A. Tränkner. . Biologische Bekämpfung vonpilzlichen Panzenkrankheiten mit kompostierten organischenReststoffen. In: Univ. of Bonn (ed.) Verantwortung für die ZukunKlima- und Umweltforschung an der Universität Bonn. – .

P. Storms is microbiologist, W. Brinton is agricultural chemist, and E.Evans is biologist for Woods End Research Laboratory; J. Hi ll is in theresearch department for Johnny’s Selected Seeds of Albion, Maine.

* William Brinton can be contacted at <[email protected]>.

Compost Teas: Microbial Hygiene and Quality In Relation to Method of Preparation

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