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EFFECTIVE
MICROORGANISMS
Av Singh
There are few agricultural inputs that can transcend the boundaries of various
forms of agriculture, yet many conventional, organic and biodynamic farmers
espouse the merits of a fermented cocktail generically referred to as EM.
discovered and developed by a Japanese
agronomist Teruo Higa. Dr. Higa’s concept
is loosely based on a theory that there are three
groups of microorganisms in the soil, namely 1)
positive (regeneration); 2) negative (decomposition,
degeneration); and 3) opportunists. According to the
concept, the ratio of positive to negative is critical
in determining whether
the soil will be
regenerating or
degenerating because the
opportunists will follow
the predominant trend.
Dr. Higa formed the
concept by simply
observing soils in nature. He classified soils into four
categories based on the activities and functions of
the predominant microorganisms, but notes that
most soils are a composite of the four classes:
Trichoderma, Aspergillus and Streptomyces) that produce
copious amounts of antibiotics. The microflora in
these soils is generally aerobic (similar to compost
tea) and the soil is characterized by excellent water
retention and infiltration and generates a pleasant
earthy odour during organic matter decomposition.
In contrast with compost tea, EM are
cultured and produced under
anaerobic fermentation.
3. Soils that perform beneficial fermentations
including the breakdown of complex organic
molecules into simple
organic molecules and
inorganic nutrients such
as amino acids, vitamins
and antioxidants (all of
which contribute to
enhanced plant growth).
These soils are generally characterized with a pleasant
fermentative odour and have favourable soil physical
properties. Moreover, despite being dominant with
anaerobic microbes there are few pathogenic fungi
or bacteria and the production of methane, ammonia
and carbon dioxide are minimized.
1. Disease-inducing soils contain pathogenic
microorganisms, such as Fusarium, which often
comprise a significant proportion of the microbial
population (up to twenty percent). Dr. Higa concludes
that ninety percent of agricultural land worldwide
can be classified as having disease-inducing soils and
notes that in these soils the addition of high-N organic
matter (i.e. fresh manure) leads to incomplete
oxidation and results in malodorous and plant toxic
substances. Moreover, these soils are characterized
by having poor physical properties (i.e. compaction)
and many plant nutrients are immobilized into
unavailable forms.
4. Soils that contain significant populations of
microorganisms that fix atmospheric nitrogen and
carbon dioxide into amino acids, carbohydrates, and
proteins. Most of us are familiar with Rhizobium and
their symbiotic relationship with legumes to fix
nitrogen, however, Phycomycetes (fungi that look like
algae) and blue-green algae can fix nitrogen as well.
These soils can maintain their fertility with only
minor additions of organic matter.
From the above, it is obvious that the idealized
soil would perform beneficial fermentation (soil #3)
and with disease-suppressive abilities (soil #4). Dr.
Higa developed EM to transform disease-inducing
2. Disease-suppressive soils are those dominated
by antagonistic microbes (e.g. Penicillium,
www.cog.ca
The Canadian Organic Grower
Summer 2007 –
35
E
ffective micororganisms (EM) were
soils into highly productive
agricultural soil. EM contain over
eighty selected species of
microorganisms including
predominant populations of lactic
acid bacteria and yeasts, and
smaller populations of photo-
synthetic, N-fixing bacteria and
actinomycetes.
EM technology differs
significantly from that of aerobic
compost tea, despite both having
benefits to soil life. In contrast with
compost tea, EM are cultured and
produced under anaerobic
fermentation and generally the
microorganisms are of a known
species and quantity. As a result,
EM are the most studied microbial
inoculants with overwhelmingly
positive results (in terms of crop
yield, disease suppression and pest
control).
EM are used in agriculture via
a number of methods. EM are
inoculated into the rhizosphere
(around the root) with the
intention to regenerate soil,
increase yields, or improve
nutrient content of the crop. EM
have also been used in livestock as
a feed additive in poultry and have
been added to ruminant feed to
increase digestibility. EM have
been used to spray on broiler
litter, cattle and sheep bedding to
help remove odours as well as tie
up nutrients. Similarly, EM have
been used extensively in
composting as a catalyst for
decomposition.
EM Bokashi is starter made
from a mix of fermented organic
waste, molasses0 and wheat bran.
It contains large populations of
EM which are dormant and when
mixed with organic waste such as
kitchen scraps or manure, the EM
are activated and proliferate to
produce rich compost full of
How to make Bokashi
Ingredients:
100 lb wheat bran
12 L warm water
240 ml molasses
240 ml EM
Prepare a diluted solution of EM, molasses and water at a
ratio of 1:1:100.
Mix well and pour over bran and continue to mix until the
final product is about 30% moisture
Place the material in a barrel and place a lid on the container
to create an anaerobic condition.
Allow 3–5 weeks in the summer and 7–10 weeks in the winter
and the bokashi should have a sweet and sour fermented smell
(but not putrid).
The pH of the bokashi should be about 5. The material
should be used immediately.
nutrients and
antioxidants. As well,
Bokashi works
extremely well when
added to the
finishing phase of
aerobic compost
piles.
The literature on
EM is over-
whelmingly favour-
able and includes
many peer-reviewed
publications that demonstrated a
wide-spectrum of benefits
including: increased seed protein,
crude fat, and seed yield in
soybeans; increased N uptake by
cowpea from crop residues;
control of Sclerotinia in turfgrass;
increased yields in banana,
oranges, peanuts, papayas,
mangos; efficiency of compost
production from three months to
three weeks, etc. From this
superficial scan of the literature,
EM appear to have been
successful in agronomic
applications worldwide, but data
are lacking from Canadian
experiences. For those growers
using EM technology in their
agricultural practices, I would love
to hear your testimony on the
products you used.
Av Singh, PhD, PAg, is the Organic
and Rural Infrastructure Specialist
with AgraPoint in Nova Scotia and
is available for comment or question
at 902-896-0277 or at
a.singh@agrapoint.ca.
For details on propagating EM
using the “Bokashi method,” see
www.cityfarmer.org/bokashi.html.
36
– Summer 2007
The Canadian Organic Grower
www.cog.ca
EM increased seed yield in soybeans.
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