FORMAL RECOMMENDATION BY THE

NATIONAL ORGANIC STANDARDS BOARD (NOSB) 

TO THE NATIONAL ORGANIC PROGRAM (NOP) 

Date: ____11-09-06___________________

Subject: NOSB Recommendation for Guidance: Use of Compost, Vermicompost, Processed Manure and 

Compost Tea. 

Chair: Kevin O’Rell 

Recommendation

The NOSB hereby recommends to the NOP the following: 

Rulemaking Action: ________ 

Guidance Statement: ____XX_

Other: ________ 

Statement of the Recommendation (including Recount of Vote): Producers of any agricultural commodity 

or product certified as organic under the National Organic Program (NOP) must meet the fundamental 

requirements for processing and applying plant and animal materials for soil fertility and crop nutrient 

management practices as described in Section 205.203 (c) of the final regulation. Examples of plant and 

animal materials are described in Section 205.203 (c) 1-3. This recommendation denotes other materials 

and practices that would be acceptable under 205.203 (c) (2) which applies to plant and/or animal 

material mixes. See attachment for details of 4 recommendations. 

NOSB VOTE 

Motion: Gerald Davis Second : Jennifer Hall 

14 Yes 0 No 0 Abstentions 0 Absent 

Rationale Supporting Recommendation (including consistency with OFPA and NOP): To provide guidance for 

certain types of compost and manure inputs commonly used in organic farming that were not directly addressed in 

the rule. To provide guidance and clarification on 2 previous NOSB recommendations: April 2002 Compost Task 

Force Recommendation and October 2004 Compost Tea Task Force Report and Recommendation. 

Response by the NOP:

Page 1 of 24 
National Organic Standards Board 

Crops Committee Recommendation for Guidance 

Use of Compost, Vermicompost, Processed Manure, and Compost teas 

 October 19, 2006 

Introduction

Section 205.203(c) of the soil fertility and crop nutrient management practice standard in the USDA 

NOP Rule sets forth the fundamental requirement for processing and applying plant and animal 

materials. The section states, “The producer must manage plant and animal materials to maintain or 

improve soil organic matter content in a manner that does not contribute to contamination of crops, soil, 

or water by plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited substances”. 

Subsequently, Section 205.203(c) states that plant and animal materials include: raw animal manure 

(205.203(c)(1)), composted plant and animal materials (205.203(c)(2)), and uncomposted plant materials 

(205.203(c)(3)). The Rule in this section also contains management restrictions for crops on which raw 

manure has been applied and also specifies the composting conditions that must be maintained to 

produce compost. Certain types of compost and manure based inputs commonly used in organic 

farming were not directly addressed in the rule, such that additional information and rule clarification 

was needed. Two different task forces were commissioned to make recommendations on compost, 

vermicompost, processed manures, and compost tea. 

In April, 2002 the Compost Task Force Recommendation was presented to the NOSB and subsequently 

accepted as a recommendation to the NOP. In October 2004, a separate report and recommendation was 

presented to the NOSB by the Compost Tea Task Force. That document was also accepted by the 

NOSB and the Crops Committee was directed by the Board to determine the necessary work that needed 

to be done to clarify these documents to the public. 

The intent of this current document is to point out and summarize the recommendations contained 

within both reports that are relevant to clear, concise guidance on the production and use of the compost 

and manure materials listed above. The complete reports of the task forces are included with this NOSB 

recommendation as supporting information only in Addendum A (Compost Task Force Report) and 

Addendum B (Compost Tea Task Force Report). 

Definitions- Excerpted from Task Force Reports with modification 

Composting- A process in which organic matter of plant and/or animal origin is managed to achieve 

aerobic decomposition and an increase in temperature in order to enhance its physical and nutritive 

properties as a soil amendment while minimizing pathogenic organisms. 

Compost- The product of the composting process defined here. 

Compost tea- A water extract of compost produced to transfer microbial biomass, fine particulate 

organic matter, and soluble chemical components into an aqueous phase, intending to maintain or 

increase the living, beneficial microorganisms extracted from the compost. 

Processed manure- Manures that have been treated by heating and drying to reduce pathogenic 

organisms. 

Page 2 of 24 
Vermicomposting- A managed process of worms digesting organic matter to transform the material 

into a beneficial soil amendment. 

Additional definitions of words used in this document- See Glossary and definitions section of 

Appendix B 

Recommendations

Producers of any agricultural commodity or product certified as organic under the National Organic 

Program (NOP) must meet the fundamental requirements for processing and applying plant and animal 

materials for soil fertility and crop nutrient management practices as described in Section 205.203 (c) of 

the final regulation. Examples of plant and animal materials are described in Section 205.203 (c) 1-3. 

This recommendation denotes other materials and practices that would be acceptable under 205.203 (c) 

(2) which applies to plant and/or animal material mixes. 

1. Compost, in addition to that described in section 205.203 (c) (2), is acceptable if: (i) made from

only allowed feedstock materials; (ii) the compost pile is mixed or managed to ensure that all of 

the feedstock heats to the minimum of 131 o

 F (55 oC) for the minimum time (3 days). 

The monitoring of the above parameters must be documented in the Organic System Plan 

submitted by the producer and verified during the site visit. An explanation of compliance with 

section 205. 203 (c) should also be presented in the plan. 

2. Vermicompost is acceptable if (i) made from only allowed feedstock materials, (ii) aerobicity is 

maintained by regular additions of thin layers of organic matter at 1-3 day intervals, (iii) 

moisture is maintained at 70-90% and (iv) duration of vermicomposting is at least 12 months for 

outdoor windrows, 4 months for indoor container systems, 4 months for angled wedge systems, 

or 60 days for continuous flow reactors. 

3. Processed manure materials must be made from manure that has been heated to a temperature in 

excess of 150 ° F (65 ° C) for one hour or more and dried to a moisture level of 12% or less, or 

an equivalent heating and drying process that produces a product that tests negative for 

pathogenic contamination by Salmonella and fecal coliform organisms. Since processed manures 

have been treated to reduce pathogenic organisms, applications are not subject to the restrictions 

placed on raw animal manure applications in §205.203(c)(1)(i, ii, iii). To prevent re-growth of 

pathogens in processed manures, post planting use on crops whose edible portion contacts the 

soil must be limited to below soil surface applications only. 

4. Compost teas must be made with potable water. Equipment used to prepare compost tea must be 

sanitized before use with a sanitizing agent as defined by 21 CFR 178.1010, using allowed 

materials found on the National List. Compost tea must be made with compliant compost or 

vermicompost, using the NOSB recommendation for compost and vermicompost mentioned 

above, and as defined in section 205.203 (c) (2) of the NOP rule. For compost tea, this applies to 

100% plant feedstock materials, in addition to manure feedstocks because non-manure compost 

feedstocks may harbor high levels of fecal bacteria. 

Compost tea made without compost tea additives can be applied without restriction. Compost tea 

made with compost tea additives can be applied without restriction if the compost tea production 

system (same compost batch, additives, and equipment) has been pre-tested to produce compost 

Page 3 of 24 
tea that meets the EPA recommended recreational water quality guidelines for a bacterial 

indicator of fecal contamination (US EPA, 2000). These indicators and the passing criteria are 

Escherichia coli (126 CFU/100ml) or enterococci (33 CFU/100ml). At least two compost tea 

batches must be tested using accepted methodology (APHA-AWWA-WEF, 1999; US EPA, 

2000), with the average population of indicator bacteria across compost tea batches used as the 

measurement of passing. Each new batch of compost would require that the system quality 

assurance pre-test be conducted again as indicated. After it passes again, compost tea from the 

system can be used without restriction, provided that an annual re-test is completed. 

If compost tea made with compost tea additives has not been pre-tested for indicator bacteria, its 

use on food crops is restricted to the 90/120 day pre-harvest interval. Crops not intended for 

human consumption, ornamental plants, and grain crops intended for human consumption are 

exempt from bacterial testing and 90/120 day pre-harvest interval restrictions. Raw manure 

extracts or teas may be applied to the soil with a 90/120 day pre-harvest restriction. Foliar 

applications of raw manure extracts or teas are prohibited. Compost leachate may be applied to 

the soil with a 90/120 day pre-harvest restriction. Foliar applications of compost leachate are 

prohibited. 

Compost extracts - resulting from any mixture of compost, water, additives, and adjuvants that 

are not held for more than one hour before use - may be applied without restriction. 

Compost tea or compost extracts are not allowed for the production of edible seed sprouts. 

Committee vote 

5 yes 0 no

NOSB VOTE 

Motion: Gerald Davis Second : Jennifer Hall 

14 Yes 0 No 0 Abstentions 0 Absent 

Page 4 of 24 
Addendum A 

National Organic Standards Board 

Compost Task Force Recommendation 

April 18, 2002 

INTRODUCTION 

Section 205.203(c) of the soil fertility and crop nutrient management practice standard in the USDA 

standard sets forth the fundamental requirement for processing and applying plant and animal materials. 

The section states, “The producer must manage plant and animal materials to maintain or improve soil 

organic matter content in a manner that does not contribute to contamination of crops, soil, or water by 

plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited substances”. 

Subsequently, Section 205.203(c) states that plant and animal materials include raw animal manure 

(205.203(c)(1)), compost (205.203(c)(2)), and uncomposted plant materials (205.203(c)(3)). The USDA 

standard establishes that raw animal manure and uncomposted plant materials are distinct materials that, 

when combined and processed, yield compost. The standard also contains management restrictions for 

crops on which raw manure has been applied and specifies the conditions that must be maintained to 

process compost. Other than the common requirement that all production practices used in organic 

production must maintain or improve the natural resources of the operation, including soil and water 

quality, there are no processing or application restrictions or conditions for using composted or 

uncomposted plant materials that are not mixed with animal materials. 

At its Washington, DC meeting in October 2001, the National Organic Standards Board (NOSB) 

reviewed the provisions in the USDA standard for processing and applying plant and animal materials. 

While supportive of the fundamental requirement established in Section 205.203(c), the NOSB 

expressed concern that the provisions in Section 205.203(c)(1)-(3) could excessively restrict the 

processing and application of beneficial plant and animal materials. The NOSB identified specific 

weaknesses in this part of the practice standard, including: 

*The C:N ratio range for compost is too narrow. Quality compost can be made with C:N ratios 

from as low as 15:1 and up to 60:1. 

*The requirement for turning compost in a windrow system five times is too prescriptive. 

*The terms in-vessel, static aerated, windrow, and raw manure are not defined. 

*Compost tea is not addressed 

*Vermicompost products are not addressed 

*Manures that have been heat treated to eliminate pathogenic organisms without composting are 

not addressed. 

The NOSB concluded that the USDA standard should be clarified to accommodate a broader range of 

plant and animal materials and related processing practices than specified in Section 205.203(c)(1)-(3). 

The intent of the crop nutrient and soil fertility management practice standard should be to identify 

fundamental management parameters and to establish threshold requirements for complying with those 

Page 5 of 24 
parameters. Site-specific variation in feedstock materials, management practices, and production 

requirements dictate that organic producers exercise flexibility in managing plant and animal materials 

on their operations. The NOSB established the Compost Task Force to clarify the parameters and 

requirements in the USDA standard for processing and applying plant and animal materials in organic 

crop production. 

The Task Force concurs with the NOSB that many certified organic farmers use plant and animal 

materials that are not adequately defined or described in Section 205.203(c)(1) – (3). Examples of 

materials that are incompletely addressed in the USDA standard are compost and its liquid extract 

compost tea, vermiculture products, and processed manure products. The Task Force is especially 

concerned that many producers process compost by selecting and managing plant and animal materials 

differently than the specifications established in Section 205.203(c)(2)(i)-(iii). This recommendation 

provides producers and certifying agents with a more comprehensive description of the plant and animal 

materials allowed in organic crop production and the conditions under which they must be processed. 

Since it is impractical to describe every combination of plant and animal material and establish how it 

must be processed, this recommendation should serve as guidance for producers and certifying agents. 

Full compliance with the provisions of Section 205.203(c) must be documented in the producer’s 

organic system plan. 

The Task Force endorses the fundamental requirement in Section 205.203(c) that all plant and animal 

materials used in organic crop production must be managed to “maintain or improve soil organic matter 

content in a manner that does not contribute to contamination of crops, soil, or water by plant nutrients, 

pathogenic organisms, heavy metals, or residues of prohibited substances”. The Task Force interprets 

the subsequent provision that “Animal and plant materials include” not to be restrictive but rather as 

allowing examples of such materials other than those specifically provided for in Section 205.203(c)(i)-

(iii). This recommendation includes descriptions and conditions for four such allowed plant and animal 

materials: compost, compost tea, vermicompost products, and processed manures. The Task Force 

recommends that producers and certifying agents use the parameters established in Section 205.203(c) 

and the management practices outlined in this recommendation for specific plant and animal materials to 

evaluate compliance on a site-specific basis. The Task Force is not recommending changes to the 

practice standard provisions for processing or applying raw manure or uncomposted plant materials. 

1. Compost 

Definition: 

Compost: Organic matter of plant and/or animal origin managed to promote aerobic decomposition and 

an increase in temperature to enhance its physical and nutritive properties as a soil amendment while 

minimizing pathogenic organisms. Compost must achieve a minimum temperature of at least 131oF (55 

oC) and remain there for a minimum of 3 days. 

Producing compost that improves soil organic matter while not contributing to contamination of crops, 

soil, or water by plant nutrients, pathogenic and parasitic organisms, heavy metals or residues of 

prohibited substances requires careful management. The fundamental conditions for composting are: 

1) Compost shall incorporate only allowed feedstock materials, except for incidental residues that 

will not lead to contamination; 

2) Compost shall undergo an increase in temperature for a period of time to a level that minimizes 

pathogenic organisms; 

3) Compost shall release H20 and CO2 with a resultant loss of volume and weight; 

Page 6 of 24 
4) Compost shall undergo a decrease in carbon to nitrogen ratio and an increase in nutrient 

stability. 

The primary feedstock materials for making compost are organic matter of plant and animal origin. The 

USDA standard defines organic matter as “the remains, residues, or waste products of any organism.” 

Organic matter of plant and animal origin includes crop residues, non-crop plant material such as leaves 

and food waste, and manure and other residues from animal bodies including soil invertebrates. 

Compost may be produced from a single material of plant or animal origin or from the combination of 

multiple materials. The producer may add a natural nonagricultural material or a synthetic material 

allowed in organic crop production to compost for a specific management purpose such as improved 

porosity. When sourcing feedstock materials, the producer must consider their origin and comply with 

the requirement to prevent contact between organically managed crops and prohibited substances. 

Composting requires that the producer combine and manage feedstock materials to achieve a 

documented increase in temperature. Composting begins in the mesophilic range (50oF - 105oF) and 

moves into the thermophilic range (in excess of 105oF) as decomposing organic matter of plant and 

animal origin releases energy as heat. Compost must achieve a recognized minimum temperature of at 

least 131oF (55 C) and remain there for a minimum interval of 3 days to minimize pathogens and 

parasites. Compost piles must be turned or be managed in some other acceptable way to ensure that all 

of the feedstock heats to the minimum temperature. Composting materials must be passively or actively 

aerated by the design of the pile or through turning. Physical maturation of compost transforms the 

feedstock materials and little or no trace of their original nature is distinguishable upon completion. 

Particles in finished compost have been reduced in size and become consistent and soil like in their 

texture. After achieving a minimum temperature of 131oF for a minimum of 3 days, compost should 

cure in the mesophilic range for at least 45 days or until the producer can document that it is suitable for 

soil application. Compost maturity involves physical and chemical components and must include an 

appraisal of potential antagonisms between the compost and plant or soil health such as excessive 

nutrients or salts. 

A producer must document in their organic system plan all management provisions or practices related 

to the fundamental conditions for making compost: use of allowed feedstock materials, temperature 

elevation and maintenance, decreases in weight, volume, and carbon to nitrogen ratio, and increase in 

nutrient stability. The certifying agent must concur that the provisions in the organic system plan for 

making compost will fulfill the parameters for these conditions. Procedures for documenting compliance 

include measuring temperature, time, moisture content, chemical composition, biological activity, and 

particle size. These measurements may include testing feedstock materials and compost for one or more 

characteristics including initial and final carbon to nitrogen ratios, stability (using ammonia/nitrate ratio, 

O2 demand, CO2 rate or other standard tests), or pathogenic organisms. 

2. Compost and Vermicompost teas 

The use of a liquid compost extract, or “compost tea”, raises special issues. The preparation and use of 

compost tea and compost extract has been increasing in the U.S. during recent years. Organic producers 

especially are interested in compost teas and extracts because the preparations reportedly provide some

degree of control of foliar and root pathogenic organisms. Various methods and practices have 

developed for production of the teas or extracts since the practice originated some years ago in Europe. 

However, recent research at the USDA Agricultural Research Service’s labs in Beltsville, MD and 

Corvallis, OR shows that certain approaches to compost tea or extract preparation are conducive to 

growth of enteric bacterial pathogenic organisms, such as enterotoxigenic E. coli and Salmonella. The 

Page 7 of 24 
practices and procedures that lead to pathogen growth in the prepared teas and extracts involve the 

addition of supplemental nutrients such as sugars, molasses or other readily available (soluble) carbon 

sources during batch production. 

The researchers did not observed growth of enteric pathogenic organisms when compost tea or extract 

was prepared only with water and high quality compost. By high quality compost, they mean compost 

that has met criteria for destroying pathogenic organisms, i.e., 131oF for 3 days, or compost that has less 

than 3 MPN salmonella per 4 grams compost (dry weight) and less than 1000 MPN fecal coliforms. The 

critical determinant regarding pathogen growth in compost teas and extracts is the addition of the carbon 

sources like sugars, molasses, or yeast or malt extracts during the “brewing” phase. 

Recommendation: Compost teas if used in contact with crops less than 120 days before harvest must be 

made from high quality compost described above and not prepared with addition of supplemental 

nutrients such as sugars, molasses or other readily available (soluble) carbon sources. 

3. Vermicompost materials 

Definition: 

Vermicomposts are organic matter of plant and/or animal origin, consisting mainly of finely-divided

earthworm castings, produced non-thermophilically with bioxidation and stabilization of the organic 

material, due to interactions between aerobic microorganisms and earthworms, as the material passes 

through the earthworm gut. 

Vermicomposting, while not contributing to contamination of the environment by heavy metals, needs 

careful preparation and management of the organic wastes. Feed stocks for vermicompost materials 

include organic matter of plant or animal origin; either a single material or mixture, preferably 

thoroughly macerated and mixed before processing. Pathogenic organisms are eliminated in 7-60 days, 

depending on the technology used. All vermicomposting systems depend upon regular additions of thin 

layers of organic matter at 1-3 day intervals to maintain aerobicity and avoid temperature increases 

above 35 degrees C (95 degrees F) which will kill the earthworms. Permitted methods and required 

duration of vermicomposting include outdoor windrows (6-12 months), angled wedge systems (2-4 

months), indoor container systems (2-4 months) and continuous flow reactors (30-60 days). 

Earthworms fragment the organic wastes into finely-divided materials with a low C:N ratio, high

microbial activity, nitrogen mostly in the nitrate form, and potassium and phosphorus in soluble forms. 

For most organic wastes, no traces of the raw materials are seen. Odors disappear within 48-72 hours of 

vermicomposting and the finished product should have an odor similar to soil. Processing must be 

maintained at 70-90% moisture content with temperatures maintained in the range of 18-30 degrees C 

(65-86 degrees F) for good productivity. This should be achieved by monitoring temperatures regularly 

to regulate timing of additions of wastes and adding moisture through fine sprays as required. 

4. Processed manure materials 

Manures that have been treated to reduce pathogenic organisms are considered to be “processed 

manure” materials. Processed manure materials must be made from manure that has been heated to a 

temperature in excess of 150°F for one hour or more, dried to a moisture level of 12% or less, or frozen. 

Since processed manure materials will not contribute to contamination of the soil by pathogenic 

organisms, they may be managed with many of the same requirements as compost. Like compost, 

Page 8 of 24 
processed manure materials do not have to be incorporated into the soil and therefore can be applied as a 

top-dress or side-dress. Similarly, there is no waiting period between application of processed manure 

materials and harvest of the crop. Unlike compost, however, these materials are highly soluble and have 

reduced biological activity. Therefore, they should not be used as a primary source of nutrients. 

CONCLUSION 

The Compost Task Force concurs with the NOSB that Sections 205.203(c)(1) – (3) of the USDA 

standard do not sufficiently define or describe a variety of beneficial soil amendments and fertilizers that

have long been used in organic crop production. The Task Force endorses the fundamental requirement 

in Section 205.203(c) that all plant and animal materials used in organic crop production must be 

managed to “maintain or improve soil organic matter content in a manner that does not contribute to 

contamination of crops, soil, or water by plant nutrients, pathogenic organisms, heavy metals, or 

residues of prohibited substances”. The Task Force supports amending the soil fertility and crop nutrient 

management practice standard by incorporating a comprehensive understanding of allowed materials 

and practices. Site-specific variation in feedstock materials, management practices, and production 

requirements dictate that organic producers exercise flexibility in managing plant and animal materials 

on their operations. Pending amendment of the USDA standard, the Task Force recommends that 

producers and certifying agents adhere to the management practices contained in this report when using 

compost, compost tea, vermicompost materials, and processed manure materials in organic crop 

production. 

Page 9 of 24 
Addendum B: 

National Organic Standards Board 

Compost Tea Task Force Report 

April 6, 2004 

Introduction 

 In 2003, the National Organic Standards Board convened a Compost Tea 

Task Force to review the relevant scientific data and report their recommendations on ‘What

constitutes a reasonable use of compost tea?’ The Task Force was composed of 13 

individuals (Appendix B) with knowledge and expertise in organic farming practices, organic 

certification, EPA pathogen regulations, compost, compost tea production and analysis, plant 

pathology, food safety and environmental microbiology. Throughout their discussions, 

members consistently acknowledged the growing interest among certified organic and 

conventional growers to use compost teas, and the need to develop effective biologicallybased tools to manage plant fertility, pests, and diseases. A major focus of the Task Force was 

concern about the potential for compost tea to contaminate edible plants with human 

pathogens as regulated in Section 205.203 of the USDA National Organic Program Final Rule. 

Addressing potential contamination by human pathogens required an examination of compost 

tea production and use practices, along with the underlying science relative to human 

pathogen contamination of crop plants. 

 Use of the terms compost and vermicompost in this report refer to the definitions set forth in 

the NOSB Compost Task Force report of April, 2002 (NOSB, 2002). These definitions are 

printed in the glossary below, along with additional terminology and definitions used in this

report. Hereafter in this report, ‘compost’ shall refer to both compost and vermicompost. 

Likewise, ‘compost tea’ shall refer to both compost tea and vermicompost tea. 

Background 

 Compost tea practitioners are largely responsible for developing the wide array of compost 

tea production practices and uses of compost tea in plant pest, disease, and fertility 

management programs (reviewed in Brinton, 1995; Brinton et al, 1996; Diver, 1998 and 2001; 

Ingham, 2003; Quarles, 2001; Scheuerell and Mahaffee, 2002; Touart, 2000). In comparison to 

the extensive experiences reported by practitioners, relatively few peer-reviewed reports 

describe scientific studies on the production and use of compost teas; most research reports 

relate to the efficacy of compost teas for plant disease control (reviewed in Weltzien, 1991; 

Scheuerell and Mahaffee, 2002). Because much of the available information on compost tea 

practices and effects has not been rigorously or scientifically documented, this report attempts 

to distinguish between existing practitioner-based knowledge [practice] and scientific 

knowledge that is supported by controlled, replicated experiments [science]. 

 A primary reason for producing compost tea is to transfer microbial biomass, fine particulate 

organic matter, and soluble chemical components of compost into an aqueous phase that can 

be applied to plant surfaces and soils in ways not possible or economically feasible with solid 

compost. While compost tea is made in a variety of ways, all methods are similar in having 

water as the first, and compost as the second, most abundant starting materials. Compost tea 

Page 10 of 24 
production methods diverge based on several properties, particularly the intent to maintain a 

minimum level of dissolved oxygen. Other distinguishing factors are the ratio of compost to 

water, addition of supplemental nutrients designed to increase microbial biomass (in this report 

termed ‘compost tea additives’), and the duration of the production process. At the time this 

committee gathered information to review (2003-2004), the predominant compost tea 

production method practiced in the United States is commonly termed actively aerated 

compost tea, which is the product of the following general process. Usually compost is filled 

into a porous container, which is then suspended in a water-containing vessel, typically 1 part 

compost to 10-50 parts water. Constant mechanical energy input is used to provide aeration 

either by air injection directly into the water or by re-circulation of the water, typically for 12-24 

hours. Compost tea additives, such as molasses, yeast extract, algal powders, when included, 

substantially increase microbial biomass in the aqueous phase from microorganisms extracted 

from the compost. Often actively aerated compost teas are made using one of many 

commercially produced “brewers”, however, many home-made brewers are also in use. 

 A second form of compost tea is termed either non-aerated compost tea or passively 

aerated compost tea, and is the product of the following general process. Typically 1 part 

compost is mixed with 3-10 parts water in an open container, where it remains with or without 

daily stirring, for at least several days, often for 1 to 3 weeks. Compost tea additives are 

infrequently added to non-aerated compost tea. 

 For the purposes of distinguishing compost tea production practices that have the potential 

to support growth of bacterial pathogens, this report considers any mixture of compost and 

water that is held for longer than one [1] hour before initiating application to be a form of 

compost tea. Any mixture of compost and water that is held for less than one hour before 

initiating application is considered a compost extract (see Glossary herein for a definition of 

compost extract; see Scheuerell and Mahaffee, 2002, for a discussion). 

 Before use, compost teas are typically filtered to a degree necessary to avoid plugging the 

sprayer or irrigation system used for application. Spray adjuvants are sometimes added 

immediately prior to application. 

Background issues associated with human pathogen contamination 

 The National Organic Program (NOP) specified composting standards for manure and 

mandated a 90/120 day pre-harvest interval for land application of non-composted manure. 

These requirements were established to reduce the potential for transfer of human pathogens 

to food crops from raw manure. Time-temperature criteria for thermophilic composting provides 

a basis for this disinfection process that further reduces pathogens (PFRP), however, meeting 

the criteria does not guarantee the complete destruction of all pathogens in every particle of 

compost. The number of human pathogens surviving may be so low that they are undetectable 

by standard laboratory procedures used in quality assurance testing. This does not mean that 

the process was deficient, but simply indicates that the test cannot guarantee a pathogen-free 

result for the entire mass, and that the test has limits of sensitivity. It does show that the 

pathogen content of the organic mass is substantially less than it was prior to composting. With 

both the time-temperature exposure data and before/after composting test results, compost 

producers can document that their process meets the standards for pathogen limits stablished 

for use and general distribution of composted fecal-matter as a soil amendment (US EPA, 

1993; FDA, 1998). 

Page 11 of 24 
 For compost tea, the use of compost tea additives to encourage growth of beneficial, 

nonpathogenic microbial populations from compost can have non- target effects, e.g., the 

additives can likewise support growth of bacterial human pathogens from undetectable to 

easily detectable numbers, in liquid microbial cultures, as preliminary investigations have 

demonstrated (discussed further below). This is the basis for concern about compost tea 

production practices that use compost tea additives to increase microbial populations; thereby 

potentially posing a risk of contaminating crop plants with human pathogens due to 

introduction of pathogenic bacteria (Patricia Millner, personal communication). The concern is 

similar to that of EPA’s Solid Waste bureau and other State regulating bodies which restrict reintroduction of fresh decomposable substrates into composts that have previously met heat 

standards, owing to risk of pathogen regrowth. These concerns led the NOP to state that 

compost tea does not satisfy ξ205.203 Soil fertility and crop nutrient management practice 

standard (c) The producer must manage plant and animal materials to maintain or improve soil 

organic matter content in a manner that does not contribute to contamination of crops, soil, or 

water by plant nutrients, pathogenic organisms, heavy metals, or residues of prohibited 

substances (NOSB Compost Task Force Recommendation, 2002; as amended by the NOP). 

However, there is not unanimous agreement on these and other data, which the Task Force 

was aware of, suggesting that the evidence of dangers from pathogens is inconsistent. 

 Although concern exists, there have been no reported cases of food borne illness from the 

use of compost tea, but there have been no epidemiological health/microbial studies done to 

evaluate this effect. Because gastrointestinal disease cases in the US are notoriously 

underreported and of unknown cause (Mead et al., 1999), lack of evidence cannot be used to 

support evidence of no problem. The committee acknowledges that proactive protective 

measures should be considered when the contamination of fresh produce with human 

pathogens is an issue. For compost tea, averting the theoretical possibility of contaminating 

crops with human pathogens can be approached by implementing measures that reduce the 

potential for pathogens to enter compost tea production systems, and perform quality 

assurance testing to demonstrate that a specific compost tea production system produces 

compost tea that meets microbiological quality guidelines. 

Glossary and definitions 

A brief list of relevant terms used in this report is provided below. 

• Composting. A managed process in which organic materials, including animal manure and 

other residuals, are decomposed aerobically by microbial action. “Thermophilic” composting 

refers to the time-limited, self-heating process in which heat generated by microbial respiration 

is retained in the mass of a pile or windrow such that vulnerable pathogenic microorganisms 

are destroyed. Compost is defined by the NOSB Compost Task Force (NOSB, 2002) as 

“Compost, in addition to that described in section 205.203 (c) (2), is acceptable if (i) made only 

from allowed feedstock materials, except for incidental residues that will not lead to 

contamination, (ii) the compost undergoes an increase in temperature to at least 131 degrees 

F (55 degrees C) and remains there for a minimum of 3 days, and (iii) the compost pile is 

managed to ensure that all of the feedstock heats to the minimum temperature.” See also 

Vermicompost below. 

• CFU. Colony-forming unit; a term used in microbiology to express the number of microbes in 

a sample that produced colonies on nutrient agar in petri plates. 

Page 12 of 24 
• Compost extract. Any mixture of compost and water, additives, and adjuvants that is not 

held for more than one hour before use. Compost extracts lack sufficient holding time for 

microorganisms to multiply and grow significantly. 

• Compost leachate. Liquid that has leached through a compost pile and collects on the 

ground, compost pad, or collection ditches, puddles, and ponds. 

• Compost tea additives. Materials separate from compost and water that are added in the 

process of making compost tea that are presumed to sustain and enrich microbial growth. 

These are distinct from spray adjuvants that are tank mixed immediately prior to application of 

compost tea. Examples include but at not limited to the following: molasses, yeast extract, fishbased products, kelp, and green plant tissue. 

• Disease vector. Animals including rodents, flies, and birds that are capable of transferring 

human pathogens to other materials. 

• Manure extract. Water suspension containing raw, non-disinfected manure; when the 

suspension is maintained for several hours or more it is sometimes referred to as manure tea. 

• Microorganism. Bacteria, fungi (molds, yeasts), protozoans, helminths, and viruses. The 

terms microbe and microbial are also used to refer to microorganisms. 

• Pathogen. A microorganism capable of causing disease or injury; used to refer to “plant” or 

to “human” pathogens. Parasite and parasitic refer to infectious protozoans and helminths. 

Helminth and helminth ova refer to parasitic worms, e.g., roundworms, tapeworms, Ascaris, 

Necator, Taenia, and Trichuris, and ova (eggs) of these worms. (See Appendix A for a list 

of pathogens of concern). 

• Indicator organism. A microorganism that is used for monitoring whether a certain set of 

pathogens might be present. 

• Potable water. Water suitable for human consumption. 

• Sanitize. To treat equipment and surfaces by a process that is effective in destroying or 

substantially reducing the numbers of microorganisms of public health concern, as well as 

other undesirable microorganisms. Sanitizing agents are described and defined in 21 CFR 

178.1010. 

• Spray adjuvants. Any material added to compost tea immediately prior to application of 

compost tea. These may include materials that are designed for wetting & sticking agents, 

plant nutrients, and those materials that sustain and enrich microbial growth, but because of 

the short time frame between addition and application, there is a very low probability of 

multiplying undesirable microorganisms in the spray tank. 

• Vermicomposting. Process of worms digesting organic matter to transform the material into 

a beneficial soil amendment. Vermicompost is defined by the NOSB Compost Task Force 

(NOSB, 2002) as: “Vermicompost is acceptable if (i) made from only allowed feedstock 

materials, except for incidental residues that will not lead to contamination, (ii) aerobicity is 

maintained by regular additions of thin layers of organic matter at 1-3 day intervals, (iii) 

moisture is maintained at 70-90%, and (iv) duration vermicomposting is at least 12 months for 

outdoor windrows, 4 months for indoor container systems, 4 months for angled wedge 

systems, or 60 days for continuous flow reactors. “ See also Compost above. 

Compost tea applications 

 Compost tea practitioners have developed a range of compost tea uses and applications 

methods. A brief description of the most common uses and application methods for compost 

tea follows. This information was used to develop an understanding of compost tea 

applications that could pose an increased potential of contaminating food crops with human 

pathogens.

Page 13 of 24 
Applications to above ground plant parts.

• Foliar spray. Applied through irrigation system or sprayer to aboveground plant parts. 

• Stubble digester/green manure inoculant. Applied to crop residues or cover crops, usually 

after mowing and before incorporation into the soil 

Applications to soil and soil-less potting media. 

• Soil. Application to unplanted or planted fields. For unplanted fields, applied through irrigation 

system (drip, micro sprinklers, sprinkler line, gun, wheel line, center pivot) or tractor mounted/ 

pulled sprayer. For planted fields, applied as a directed spray to areas of bare soil or through 

drip irrigation systems. 

• Soil-less media. Use to moisten media before planting or as a postplant drench. 

• Seed treatment. Soak seeds or propagation material (e.g., potato) before planting. 

• Odor suppressant. Applied to manure collection/handling areas or to ground surrounding 

compost piles to reduce production of odors. 

Plant responses to compost tea 

Grower testimonials constitute the majority of evidence that supports the use of compost tea 

as a beneficial agricultural production tool. Most testimonials have described impacts on plant 

growth or disease suppression. Relatively few rigorous scientific studies have examined the 

use of compost tea for plant disease suppression. The following information summarizes plant 

responses to compost tea and was used by the Task Force to identify areas of study that 

should receive greater scientific attention. 

Positively impact plant vigor and growth. 

A growing number of organic and conventional growers are using compost tea because they 

have observed yield and/or production efficiency gains (Schmitz, 2002; Diver, Ingham, 

Scheuerell, personal communication). 

• Postulated direct mechanisms include plant response to nutrients or phytohormone/growth 

promoting chemicals in the compost tea. 

• Postulated indirect mechanisms include altering composition and/or populations of plant 

associated microorganisms that cause a direct effect, or over time, moderation of the chemical, 

physical or biological properties of the rhizosphere/phyllosphere. Examples would be soil 

structure, pH, or reducing the effect of deleterious (nonpathogenic) microorganisms. 

Plant disease management 

• Practitioner-based knowledge [Practice] 

There have been a large number of grower testimonials in recent years suggesting that 

compost tea has improved their ability to manage plant diseases (Diver, Ingham, Scheuerell, 

personal communication). Grower experiences have indicated that both non-aerated and 

aerated compost tea can suppress the incidence and/or severity of foliar and root rot diseases. 

Page 14 of 24 
• Science-based knowledge [Science] 

• Some replicated scientific studies have indicated that both non-aerated and aerated compost 

tea can suppress the incidence and/or severity of foliar and root rot diseases, while others 

have observed no significant effect (reviewed in Scheuerell and Mahaffee, 2002; Weltzien, 

1991). 

• Lack of consistency of disease suppression by compost tea is postulated to be caused by 

variability in raw materials, the production process, nutrients and other materials tank mixed 

before application, application method and timing, pathogen pressure, and environmental 

conditions. The committee had limited data available to review (see Scheuerell, 2002; 

Scheuerell and Mahaffee, 2002; Weltzien, 1991). 

Potential Microbial Hazards Associated with Compost Tea 

There are many variables in the production and application of compost tea that could affect the 

probability of contaminating crops with human pathogens. In addition, plant properties and 

environmental conditions greatly affect survival of human pathogens. This section of the report 

discusses factors associated with compost tea production, plant properties, and environmental 

conditions that could affect the contamination of crops with human pathogens. This information 

was used by the Task Force to identify data gaps and guide the development of 

recommendations. 

Transfer or multiplication of pathogenic organisms 

• Compost tea production factors. In general, pathogens that go into the process might 

come out at the same, lower, or higher levels. Processes or materials that have a high 

probability of increasing human pathogens during compost tea production are of greatest 

concern. 

• Compost feedstocks and composting process used [Science] 

Feedstocks such as manure have a high probability of containing pathogenic organisms. 

These types of materials can be processed to reduce populations of indicator microbes and 

pathogens to acceptable levels by using approved PFRP’s. For example, Lung et al. (2001) 

recently reported that after composting cow manure E. coli and Salmonella were not detected 

after 72 hours at 45 degrees C. All data brought to the Task Force support the notion that 

compost tea made from compost and vermicompost, as defined by the NOSB Compost 

Task Force (NOSB, 2002), does not represent a risk if compost tea additives are not used. 

• Compost stability. [Science] 

Compost stability is the reactivity of composting materials, most commonly measured as the 

rate of oxygen consumption and/or rate of carbon dioxide respiration. Stability is known to 

affect the potential for Salmonella re-growth in composting biosolids (Soares et al , 1995; 

Soares, 1996; Skanavis and Yanko, 1994; Yanko, 1987; Yanko et al., 1995 ). Stability affects 

the relative quantity of nutrients originating from the compost that support the growth of a wide 

range of microorganisms, including some human pathogenic bacteria. Data is lacking on the 

relationship between human pathogen growth potential in compost tea and compost stability. 

Page 15 of 24 
• Water quality [Science] 

Potable water quality is necessary to prevent the introduction of pathogens. 

• Sanitation [Practice] 

Cleaning procedures for production and application equipment. No standards exist, but 

sanitizing agents should be used to maintain equipment free of microbial biofilms between 

uses, and accidental contamination from wind-borne dust should be avoided. 

• Disease vector access [ Science] 

Rodents, flies, and birds need to be excluded from the materials used to produce compost tea. 

• Brew time and temperature. [Practice] 

Affects the theoretical maximum number of bacterial divisions that can occur during compost 

tea production. 

• Compost tea additives. [Practice and Science] 

Materials other than water and compost added at the start of the compost tea making process 

to increase microbial biomass/populations. It should be noted that as of March 30, 

2004, only one of the studies (Duffy et al, 2004) discussed below has been published in a 

peer-reviewed scientific journal. 

• Duffy (et al 2004) related the growth of E. coli O157:H7 and Salmonella Thompson to 

concentration of molasses added to 2 types of compost with water in sealed flasks that were 

rotary shaken for 72 hours (Duffy et al, 2002). Re-growth of either pathogen was not detected 

when 0, 0.05, or 0.2% vol/vol molasses was added. Re-growth of E. coli and Salmonella was 

observed when 0.5 or 1.0% molasses was added, with 0.5% molasses supporting greater regrowth of Salmonella than E. coli. For Salmonella, composted chicken manure supported 100 

times more re-growth than composted dairy manure when 0.5 or 1.0% molasses was added; 

potentially due to the greater concentrations of inorganic nutrients in the composted chicken 

manure. This indicates that pathogen re-growth can be dependent on the concentration of 

compost tea additive used. In addition, the significant interaction between compost source 

and additives on the re-growth potential of human pathogens in this study indicates the need to 

test individual batches of compost with defined concentrations of compost tea additives 

for compost tea quality assurance testing. The nature of the production method used in the 

Duffy et al paper has been challenged as not relating to any compost tea production 

practice (Elaine Ingham, personal communication). 

• Data presented by Bess (et al, 2002) at the 2002 International Symposium Composting and 

Compost Utilization, May 6-8, Columbus, Ohio, addressed the issue of increasing populations 

of bacterial pathogens through the addition of compost tea additives. The report indicated that 

E. coli increased to various degrees with different microbial culture nutrients when incompletely 

composted material that contained detectable populations of E. coli was used in an aerated 

compost tea brewer (Bess et al, 2002). 

Page 16 of 24 
• Initial experiments presented to the Task Force by Pat Millner and Will Brinton and duplicated 

in two microbiological labs simultaneously, indicated pathogen growth could occur in compost 

teas when very low concentrations of molasses were used in combination with a compost 

substrate seeded with very low numbers of human pathogens (‘trace’ concentration, also 

referred to as ‘undetectable’ by common laboratory analysis). This resulted in growth of the 

pathogens in the compost tea to a quantity detectable by common laboratory procedures 

(Millner and Brinton, Manuscript Report to Task Force). 

• Other experiments were discussed that showed vermicompost with relatively high 

populations of E. coli resulted in variable amounts of E. coli growth depending on the 

concentration of molasses used as a compost tea additive (Elaine Ingham, personal 

communication). Related experiments using a mined humus material (no detectable E. coli) in 

place of compost resulted in no growth of E. coli over a range of molasses concentrations used 

as a compost tea additive (Elaine Ingham, personal communication). Other tests that utilized 

compost sold as part of an aerated compost tea production system or compost that had had 

below detectable levels of E. coli did not show an increase in E. coli even when compost tea 

additives were used (Scheuerell and Millner, personal communication; Brinton, personal 

communication). 

• Crop/environmental factors [Practices available, no Science available that directly 

addresses compost tea use under agronomic conditions] 

• Pre-harvest interval 

• Climate – temperature, humidity, precipitation 

• Crop architecture – UV protected sites, moisture availability, plant exudates

• Crop cleaning, processing, cooking. Crops that are dried and then cooked before 

consumption, such as grain crops, are not considered to be a significant source of human 

pathogens.

Factors Associated with Human Pathogens 

The following are factors associated with human pathogens that the Task Force 

considered while developing recommendations. 

• Actual pathogens present. The presence or growth potential of many pathogens has not 

been thoroughly evaluated for different compost teas. 

• Contamination level of compost teas. Available research has used non-stable compost 

with readily detectable populations of human pathogens or compost artificially inoculated with 

human pathogens. For artificially inoculated compost, research has demonstrated a high 

degree of variability in final pathogen populations across replications of the same compost tea 

production treatment (Scheuerell and Millner, personal communication). Data currently relate 

to pathogens suspended in the tea, rather than the number that survive on the surface of 

edible fresh produce after tea is directly applied to plant surfaces. 

• Pathogen survival. In the environment pathogen populations typically decline over time, 

unless deposited in a site with all conditions conducive for survival or growth. For example, 

Liao (2003) demonstrated that human pathogens present in dairy manure were not 

Page 17 of 24 
detectable 70 days after application to potato production fields. In a review of published data 

on the survival of human pathogens on plant surfaces, Epstein (1997) indicated that most 

studies found bacterial pathogens to survive for <1 day to a maximum of 35 days on plants, 

and the longest cited survival time of any pathogen was 68 days. 

• Crop architecture and exudate profile. Potential for the crop to enable pathogen survival or 

growth. Lettuce and apples are the best known examples for harboring bacterial pathogens in 

sites protected from environmental stress and likely releasing sufficient nutrients to support 

pathogen metabolic activity. 

• Environment. Particularly important for above ground portions of plants. Ultraviolet radiation 

and dessication are the two most important environmental factors causing pathogen 

destruction. 12 Little is known about interactions with other microorganisms on plant surfaces 

under field conditions. 

• Pre-harvest interval. If the decimal reduction time is known for a crop and general 

environment, then the interval between the last compost tea application and harvest can be 

used to compute the amount of pathogen reduction expected during that pre-harvest interval. 

• Post-harvest treatments. Removing part of the plant, sanitizing, and processing activities 

can leave unaffected, spread or kill individual pathogen cells. This depends on a number of 

factors including plant type, washing system, sanitizing system, cutting of plant tissue, and 

most importantly thermal processing. 

Data Gaps [Science needed] 

• Cost-benefit analysis. Developing a cost-benefit analysis of compost tea use will require 

confirming compost tea production and application methodologies that consistently provide a 

positive, measurable crop response. If benefits were quite certain, then the cost of 

incorporating the compost tea program compared to other production choices could be 

quantified.

• Ecology of human pathogens 

• We lack an understanding of the population dynamics of human pathogens when occurring in 

diverse microbial mixtures with active predation by higher trophic levels. The microbial diversity 

and competition found during compost tea production could inhibit or destroy human 

pathogenic bacteria. 

• Influence of water temperature and production duration on pathogen growth. For compost tea 

production, combining relatively low water temperatures with short production durations may 

provide conditions not suitable to significantly increase human pathogenic bacteria that 

have evolved optimal growth rates associated with warm-bodied animals. 

• Survival of human pathogens on crop plants, under field conditions, when inoculated at 

realistic levels. In addition, diverse microbial competition for resources and/or antagonism and 

predation by other organisms on crop plants could affect duration of survival in crop 

environments. 

• Internalization of pathogens into plants. Laboratory and greenhouse studies have shown 

incorporation of E. coli into plant tissue is possible when inoculated with very high populations 

of pathogenic bacteria. Whether this occurs on crop plants, under field conditions, or in relation 

Page 18 of 24 
to compost teas containing a realistic level of contamination has not been researched. If 

internalization of pathogens is an issue, on what plants and under what conditions needs to be 

determined. 

• Pre-harvest application interval. The aforementioned data gaps preclude a meaningful 

assessment of appropriate pre-harvest interval recommendations. 

• Compost Stability. Role of compost stability in the potential for compost to support the 

growth of pathogenic bacteria during compost tea production. 

• Feedstocks. Role of different feedstocks used to make compost in the potential for compost 

to support the growth of pathogenic bacteria during compost tea production.

• Phytotoxic reaction [Practice]. Potential for compost tea to cause phytotoxic reactions, 

particularly in relation to the compost tea production practice used. There are few reports of 

adverse effects (Diver and Ingham, personal communication). Theoretical concerns of 

phytotoxicity are based on soluble salt levels or potential accumulation of phytotoxic microbial 

metabolites during compost tea production. Potential for phytotoxic reactions could be affected 

by tea concentration, dose, crop, and environmental conditions. If a concern exists, like any 

agricultural material, the tea should be tested on a small portion of the crop and observed. 

• Dissolved oxygen content. The relevancy of measuring oxygen content of compost teas as 

a stand-alone indicator of potential pathogen growth is uncertain given than E. coli and other 

potential pathogens are facultative organisms (capable of growth in presence of oxygen). 

Recommendations 

1. Potable water must be used to make compost tea and for any dilution before application. 

2. Equipment used to prepare compost tea must be sanitized before use with a sanitizing

agent as defined by 21 CFR 178.1010. 

3. Compost tea should be made with compliant compost or vermicompost, using the NOSB 

Compost Task Force Guidelines set forth on April 18, 2002, for thermal compost and 

vermicompost, or compost as defined in section 205.203 (c) (2) of the NOP rule. For compost 

tea, this applies to 100% plant feedstock materials in addition to manure feedstocks because 

non-manure compost feedstocks may harbor high levels of fecal bacteria (Epstein, 1997). 

4. Compost tea made without compost tea additives can be applied without restriction. 

5. Compost tea made with compost tea additives can be applied without restriction if the 

compost tea production system (same compost batch, additives, and equipment) has been 

pre-tested to produce compost tea that meets the EPA recommended recreational water 

quality guidelines for a bacterial indicator of fecal contamination (US EPA, 2000). These 

indicators and the passing criteria are Escherichia coli (126 CFU/100ml) or enterococci 

(33 CFU/100ml). At least two compost tea batches must be tested using accepted 

methodology (APHA-AWWA-WEF, 1999; US EPA, 2000), with the average population of 

indicator bacteria across compost tea batches used as the measurement of passing. Each new 

batch of compost would require that the system quality assurance pre-test be conducted again 

Page 19 of 24 
as indicated. After it passes again, compost tea from the system can be used without 

restriction. If compost tea made with compost tea additives has not been pre-tested for 

indicator bacteria, its use on food crops is restricted to the 90/120 day preharvest interval. 

Crops not intended for human consumption, ornamental plants, and grain crops intended for 

human consumption are exempt from bacterial testing and 90/120 day pre-harvest interval 

restrictions. In the view of the Task Force, educating producers about the potential for 

contamination and its impacts on public health and marketing, as well as how this 

recommended quality assurance testing system would avoid potential contamination will 

provide compelling incentives for producers to follow the rules. 

6. Compost extracts - any mixture of compost, water, additives, and adjuvants that is not held 

for more than one hour before use - may be applied without restriction. 

7. Raw manure extracts or teas may be applied to the soil with a 90/120 day pre-harvest 

restriction, foliar applications are prohibited.

8. Compost leachate may be applied to the soil with a 90/120 day pre-harvest restriction, foliar 

applications are prohibited. 

9. Compost tea is not allowed for the production of edible seed sprouts. 

10. The emerging national acceptance of compost tea as a biologically-based crop production 

tool by organic as well as conventional growers clearly indicates the need for further scientific 

investigation to validate the benefits and concerns of compost tea use. The Task Force 

unanimously urges USDA and its agencies to strongly support additional research on the 

potential for crop contamination and plant disease/pest control by compost tea. There is 

an urgent national need to address critical data gaps, uncertainties, and variability in existing 

data that limited the evaluation of potential crop contamination by the current task force. Data 

are urgently needed to provide science-based recommendations on how compost tea 

production and application practices impact potential crop contamination, while at the same 

time preserve the means for improving plant health and vigor. Critical issues requiring further 

data include compost quality, compost tea additives, temperature and duration of compost tea 

production, and the population dynamics of human pathogens in microbially diverse agroecosystems relative to pre-harvest intervals for application of compost tea. 

Page 20 of 24 
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Federation. 1999. Standard methods for the examination of water and wastewater [CD-ROM]. 

20th edition. New York. 

Bess, V. H., R. B. S. Manes, and J. L. Snodgrass. 2002. E. coli survival in compost tea using 

different nutrient substrates. Proceedings 2002 International Symposium Composting and 

Compost Utilization. 

Brinton, W.F. 1995. The control of plant pathogenic fungi by use of compost teas. 

Biodynamics Jan/Feb:12-5. 

Brinton, W.F, A. Trankner, M. Droffner. 1996. Investigations into liquid compost extracts. 

Biocycle 37(11):68-70. 

Diver, S. 1998. Compost Teas for Plant Disease Control. ATTRA, Fayetteville, AR. 

http://attra.ncat.org/attra-pub/comptea.html 

Diver, S. 2001. Notes on Compost Teas: A 2001 Supplement to the ATTRA 

publication Compost Teas for Plant Disease Control. ATTRA, Fayetteville, AR.

http://attra.ncat.org/attra-pub/compost-tea-notes.html 

Duffy, B., C. Sarreal, R. Subbarao, and L. Stanker. 2004. Effect of molasses on 

Regrowth of E. coli O157:H7 and Salmonella in compost teas by B. Duffy, C. 

Sarreal, S. Ravva and L. Stanker Compost Science and Utilization, Vol. 12 (1):93-96. 

Epstein, E. 1997. Pathogens, p. 213-245 In: The Science of Composting. Technomic 

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FDA, 1998. Guidance for Industry: Guide to Minimize Microbial Food Safety Hazards for Fresh 

Fruits and Vegetables. Federal Register, October 29, 1998 Vol. 63(209):58055-58056. 

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Ingham, E.R. 2003. The Compost Tea Brewing Manual, 3rd Edition. Soil Food Web, Inc., 

Corvallis, OR. 

Liao, Ching-Hsing, C. Wayne Honeycutt, Tim S. Griffin and John M. Jemison. 2003. 

Occurrence of gastrointestinal pathogens in soil of potato field treated with liquid dairy manure. 

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Lung, A.J., C.M. Lin, J.M. Kim, R. Marshall, R. Nordstedt, N.P. Thompshon and C.I. Wei. 2001. 

Destruction of Escherichia coli 0157:H7 and Salmonella enteridtidis in cow manure 

composting. Journal of Food Protection 64: 9:1309-1314. 

Mead, P.S., Slutsker, L., Dietz, V., McCaig, L.F., Bresee, J.S., Shapiro, C., Griffin, P.M. and 

Tauxe, R.V. 1999. Food-related illness and death in the United States. Emerging Infectious 

Diseases 5:607-625. 

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Quarles, W. 2001. Compost tea for organic farming and gardening. The IPM Practitioner 

23(9):1-8. 

Scheuerell, S. 2002. Compost teas and compost amended container media. Ph.D. 

Dissertation. Oregon State University, Corvallis, OR. 

Scheuerell, S. and W. Mahaffee. 2002. Compost tea: Principles and prospects for plant 

disease control. Compost Science and Utilization 10(4):313-338. 

Schmitz, J. 2002. Compost teas work on center pivot farm. Capitol Press. Nov. 29, 2002, p. 20. 

Skanavis, C. and Yanko, W. A. 1994. Evaluation of composted sewage sludge based soil 

amendments for potential risks of Salmonellosis. Journal of Environmental Health 56(7):19-23. 

Soares, H., B. Cardenas, D. Weir, M. Switzenbaum. 1995. Evaluating pathogen regrowth in 

biosolids compost. BioCycle. June:70-74 

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Stability. Ph.D. Dissertation. University of Massachusetts, Amherst, 

MA. 

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CFR Parts 257, 403, and 503. The Standards for the Use or Disposal of Sewage Sludge. Final 

Rules. EPA 822/Z-93/001. U.S. Environmental Protection Agency. 

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Enterococci and Escherichia coli. United States Environmental Protection Agency. Office of 

Science and Technology, Washington, DC. EPA/821/R-97/004. 

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J. H. Andrews and S. S. Hirano (eds.), Microbial Ecology of Leaves. Springer-Verlag, New 

York. 

Touart AP. 2000. Time for compost tea in the Northwest. Biocycle 40(10):74-7. 

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Appendix A 

Public Health (Food and Waterborne) Pathogens of Concern in Animal Manure 

Major Concern 

E. coli 0157:H7

Listeria monocytogenes 

Salmonella

enterpathogenic 

E. coli 

Yersinia enterocolitica

Campylobacter jejuni 

Leptospira

Cryptosporidium parvum 

Giardia lamblia 

Ascaris lumbricoides 

Ascaris suum 

Hymenolepis nana

Necator americanus 

Taenia saginata

Toxocara canis 

Trichuris trichiura

Enteroviruses 

Rotaviruses 

Orthomyxovirus (Influenza A) 

Minor Concern 

Bacillus cereus 

Brucella

Citrobacter spp. 

Clostridium perfringens 

Coxiella burnetii 

Enterobacter spp. 

Erysipelotrix rhusiopathiae 

Francisella tularensis 

Klebsiella spp. 

Mycobacterium tuberculosis

Mycobacterium avium spp. 

Proteus spp. 

Pseudomonas aeruginosa 

Serratia spp. 

Staphylococcus

Streptococcus spp.

Intermediate 

Helicobacter 

Aeromonas 

Burkholderia 

Legionella pneumophilia

Toxoplasma gondii

Endotoxins 

Enterotoxins

Antibiotic resistance 

Paramyxovirus (Newcastle) 

Parapox (Orf) 

Not all pathogens are necessarily present in all manures, all the time. In terms of emerging 

diseases, Taylor et al. (2001) reported that there are 1415 infectious agents that affects 

human, including 217 viruses and prions, 538 bacteria and rickettsia, 307 fungi, 66 protozoa, 

287 helminths. Of these 868 (61%), are zoonotic, i.e. transmissible between humans and 

animals, 175 pathogenic spp. are associated with diseases considered to be ‘emerging’ 

Taylor et al. (2001) show that zootic pathogens are more likely to be emerging than existing 

and that protozoa and viruses are most likely to emerge and helminths are least likely. They 

found no association between the disease transmission route and emergence. 

Taylor, L.H., Latham, S.M., Woolhouse, M.E.J. 2001. Risk factors for human disease 

emergence. Phil. Trans. Royal Soc. London B 356: 983-989. 

Page 23 of 24 
Appendix B 

Compost Tea Task Force Members

Dr. Eric Sideman, Chair 

Maine Organic Farmers and Gardeners Association 

Dennis Holbrook, Co-Chair until he resigned from the NOSB 

National Organic Standards Board, Farmer 

Dr. Owusu Bandele 

Food for Thought Organic Farm 

National Organic Standard Board, Chair of Crop Committee 

Dr. Will Brinton 

Woods End Research Laboratory 

Esper K. Chandler 

Texas Plant & Soil Lab

Steve Diver 

ATTRA – National Sustainable Agriculture Information Service 

Dr. Clive Edwards 

The Ohio State University 

Dr. Elaine Ingham 

Soil Foodweb, Inc. 

Dr. Rosalie Koenig 

National Organic Standard Board, Chair of Material Committee and CoChair of Task force replacing Dennis Holbrook 

Dr. Frederick Magdoff 

University of Vermont 

Dr. Patricia Millner 

USDA/ARS 

Dr. Steven Scheuerell 

Oregon State University 

Ms. Zea Sonnabend 

California Certified Organic Farmers 

Dr. Larry Zibilske 

USDA/ARS

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