A Comparison of the Microbiome Population Induced by Different Microbial Foods for the Production of a Safe and Effective Aerated Compost Tea

Commodities

Practices

Solutions to the problem of
brewing a safe (pathogen-free) yet effective microbially-fed
aerated compost tea will involve DNA-testing and testing by
microscopy different kinds of microbial additives to see which
microbial food does not spike pathogenic bacterial populations of
Enterobacters, Citrobacters, and Klebsiella, in the compost tea
yet increases the number of PGPBs. 

Recent Studies of Microbial Starters for Compost
Tea

The image above is data from a study conducted by a biological
amendments company in Switzerland called EdaPro.

Appendix2_2019-032_Bioinfo

The aim of the study above was to determine the diversity and
identification / relative abundance of the microbiome of three
compost tea samples fed varying microbial additives.  The
research shows that Enterobacter populations were at their
highest in the brew that contained molasses (as were many
beneficial bacteria). 

However, in EdaPro's proprietary blend of alfalfa and kelp, there
was an increase in beneficial bacteria while Enterobacter
populations remained minimal.

In DNA-testing my own vermicompost tea that was fed a variety of
fish hydrolysate, humic acids, and kelp, I also saw an increase
in Enterobacters which are potentially pathogenic as well as an
increase in other beneficial bacteria.

Using this study as my starting point, I would like to determine
the diversity and identification of the microbiome of 5 different
compost tea samples fed with the following microbial foods:

• Alfalfa
• Kelp
• Fish hydrolysate
• Humic acids
• Molasses

By determining the presence, absence, and relative abundance of
pathogenic bacteria, I hope to make science-based recommendations
to farmers regarding the use of microbial feeds.

Defining Terminology

Safe Tea - Compost tea that is
brewed with an additive and found to have less than 100 CFU/100ml
of Escherichia coli  or 33 CFU/100ml of enterococci

Unsafe Tea - Compost tea that
is brewed with an additive and found to have a significant
increase of greater than 100 CFU/100ml of Escherichia coli or
greater than 33 CFU/100ml of enterococci.

Safe & Effective Tea - Compost tea that is
brewed with an additive and found to have a significant increase
of more than 30% relative abundance in beneficial PGPBs and less
than 100 CFU/100ml of Escherichia coli  or 33 CFU/100ml
of enterococci

Compost Tea or ACT - Aerated Compost Tea (fed or
not fed)

Research Question and
Objective

In this study, I aim to first
and foremost answer the question, "Can we brew a safe and
effective compost tea from vermicompost with the addition of
microbial food?"

Through the course of the
research and through copious record keeping, I also hope to
answer several sub-questions such as:

1. What is the safest and most effective microbial starter to use
for brewing compost tea?
2. What is the optimal brewing time to produce the safest and
most effective compost tea?
3. If Enterobacters are present in my vermicompost, can proper
brewing methods decrease their populations?  What methods
would those be?
4. Do the safest and most effective ACT treatments increase
yields, disease resistance, and nutrient density in
tomatoes?

In this study, I will measure
the presence, absence, and relative abundance of pathogenic
bacteria in 15 different treatments of compost tea from
vermicompost and one control (a total of 16 compost tea
treatments), brewed for 24 hours and 12 hours. 

Relative abundance and identification of pathogens will be
determined using DNA Testing and microbial analysis.

The compost tea treatments would be fed five different microbial
starters separately and combined in pairs as shown in the table
below.

The control will not be fed a microbial additive.

The data returned will be represented in Krona graphs and
microbiome reports provided by Aggrego Data will reveal
bacteria quantities and classifications as PGPBs (beneficial
bacteria) or not.

The analysis of this report will reveal the best performer as the
safest and most effective compost tea.

To find out the Effectiveness of Safe Aerated Compost
Tea the study will test the effects of a weekly
application of the safest and potentially most effective compost
tea as a foliar spray on 16 determinate tomatoes and see if the
compost tea will affect tomato

• Yield
• Disease-Resistance
• Nutrient-Density

Research
Hypothesis

I hypothesize that it
is possible to consistently brew a safe and effective batch of
aerated compost tea using specific microbial foods.

Current research suggests that molasses will prove to be the most
unsafe additive to use as a compost tea feed and that either
humic acids, alfalfa, and kelp, or a combination of these, may
prove to be potentially safe and effective additives to use in
brewing aerated compost tea (ACT).

A secondary hypothesis is that
a weekly foliar application of the safest and most
effective ACT treatment will deter disease, and improve yields
and nutrient density in tomatoes.

Data Collection &
Measurements

Before conducting research a water test will be conducted to
determine that the water used for compost tea production is
pathogen-free.

Findings of compost tea
treatments' microbiome identification and relative abundance of
32 samples of compost tea treatments will be logged
in this spreadsheet, during the first year/phase of this
research.

Variables: Relative Abundance of
Enterobacters, Relative abundance of PGPBs, 

Findings of the Effects of the safest and most effective ACT
treatment vs. a non-fed ACT will be stored in this second sheet
of the same spreadsheet labeled "Effectiveness of ACT
(Tomatoes).  

Variables: Yield, Disease resistance,
Nutrient-density

A total of 32 tomatoes will be transplanted in March 2025 under
hoops.  Half will be treated with the safe ACT once a week
from April through September,

Tomatoes will be weighed on harvest, the onset of diseases will
be noted and samples will be sent for nutrient testing to
Biounitrient Institute

Measuring
Nutrient-Density in Crops

With the help of
the Bionutrient Food Association
(BFA), I will send
samples of harvested trialed tomatoes to the BFA labs for
nutrient-dense analysis within a day after
harvest.  

Bionutrient
Food Association has the largest nutrition database in
crops of its kind.

How Crop Testing Works

Growing partners submit food
and soil samples to the Bionutrient Institute Lab and share
information about how those crops were managed using
the BI SurveyStack
App. This app
walks the user through detailed instructions on collecting food
and soil samples and how to package samples for shipping. After
the lab receives and processes samples, it returns a detailed
report on crop and soil nutrition, comparing it against a
spectrum of crops in its database.

Location and Choice and Map
Plotting

The location I have chosen is
the space below to be used for (6) six 6x4 beds in our production
garden on our farm, Bethany Farms, 41558 Stumptown Rd., Leesburg,
VA 20176.

Layout of Beds in Experiment

• Four beds designated through
  computer randomization will contain plantings of tomatoes and a
  weekly treatment of safe compost tea will be applied will be
  applied as a foliar spray at the seedling stage. Each crop is
  numbered 1 to 16 (SAFE TEA).
• Four beds designated
  through computer randomization will contain
  plantings of tomatoes and a
  weekly aerated compost tea to which no feed has been added, will
  be applied as a foliar spray at the seedling stage. Each crop is
  numbered from 1 to 16. (CONTROL)
• 1 represents treatments with ACT.  (SAFE TEA)
• 2 represents treatments with non-fed ACT (CONTROL)

Variable: Crop Yield,
Nutrient-Density

Observations made about tomatoes in trial