Earthworms A Gardener’s Best Friend
- Improve the physical structure of the soil.
Improve water filtration rates and absorption
rates helping the soil to drain better. Less
runoff equals less watering and less erosion.
- Their tunneling activity improves soil
aeration, porosity, and permeability.
- Increases moisture absorption by the soil and
helps make moisture available to plants. Castings
absorb water faster than soil; castings hold more
water than equivalent amounts of soil. Bhawalker
Earthworm Research Institute
- Castings have the ability to absorb moisture
from the air and hold it in a manner that plants
can use. Bhawalker Earthworm Research Institute
- 25 earthworms per square foot of soil equal 1
million earthworms per acre. Studies in England
have shown that in healthy soil forty tons of
castings per acre pass through earthworms bodies
daily. A new USA study indicates 12 million worms
per acre which move 20 tons of earth each year.
- Studies have shown that with good food sources
and favorable conditions, a field might have over
100 nightcrawlers per square yard. National Soil
- One earthworm can digest 36 tons of soil in one
year. US Soil Conservation Office
- The tunneling activity of worms helps breakup
hardpan and other compacted soils.
- Studies have shown that 30% of a field’s
respiration during the cold wet winter to spring
months is due to earthworms.
- A study in European orchards found that
earthworms could increase the pore space in soil by
75 - 100% and that earthworm burrows accounted for b
of a soils air-filled pore. Earthworm Ecology and
Biogeography in North America, 1995.
- Improve soil fertility.
Bring up minerals from deep in the subsurface
that are often in short supply in surface layers.
- Earthworm activity counteracts leaching by
bringing up nutrients from deep in the soil and
depositing them on the soil's surface as
- The burrows also allow roots to easily go down
deeper into the soil and get nutrients they could
not ordinarily reach.
- Removes litter from soil surface - earthworms
eat the litter and leave the nutrients in their
castings for plants to use as a natural fertilizer
that is non-polluting.
- Earthworms process compost residues and waste
products. The bacteria and other microbes in a
worm's gut help destroy harmful chemicals and
breakdown the organic wastes.
- Create fertile root channels - the mucus lining
of abandoned burrows are an excellent source of
nutrients and root growth promoting hormones.
- They make plant nutrients more available, worms
concentrate minerals in their castings in a form
that is easy for plants to absorb.
- Earthworms chelate nutrients, making minerals
available to plants that would otherwise be in a
form that would be chemically unavailable.
- Worms stimulate beneficial microbial
populations; nitrogen fixing bacteria are more
numerous near earthworm burrows and in their
castings. One study on bacteria and actinomycetes
found densities from 10-1,000 times greater.
Earthworm Ecology and Biogeography in North
- Plant growth stimulants such as Auxins are
produced in the castings, these hormones stimulate
roots to grow faster and deeper.
- Worms neutralize soil pH, cast analysis shows
that the product coming out of the back end of a
worm is closer to neutral than what goes in the
- Analysis of earthworm castings reveal that they
are richer in nutrients than surrounding soil,
often 3 times more calcium, several times more
nitrogen, phosphorus, and potassium. K.P. Barley,
Advances In Agronomy, Vol. 13, 1961
- Nitrogen fixing bacteria live in the gut of
earthworms and in earthworm casts and higher
nitrogenase activity, meaning greater rates of
nitrogen fixation are found in casts as compared to
- One study found that earthworms are responsible
for passing nitrogen to the soil at a rate of 100
Kg N per ha per year. Earthworm Ecology and
Biogeography in North America, 1995.
- The earthworms gut is a natural bioreactor,
which increases the beneficial microbial density in
the material it excretes to 1,000 times that of the
surrounding soil. Worm Digest, Winter 1994.
- Improve plant growth and health
- Tests have shown that crops grown in
earthworm-inhabited soil increased yields from 25%
to over 300% than in earthworm-free soil. K.P.
Barley, Advances in Agronomy, vol. 13, 1961, p.
- Earthworms help eliminate thatch in lawns and
grassy areas by eating and digesting the plant
- Studies have shown that soils rich in
earthworms have less of the harmful nematodes like
- Earthworms create soil conditions that
discourage populations of soil organisms such as
insects, nematodes and others that are harmful to
- By passing soil and organic matter through
their bodies, gradually make acid soil less acid
and alkaline soil less alkaline. The Rodale Book Of
- A recent study found that earthworm produced
compost (vermicompost) dramatically increases
germination and growth in many plants. Adding only
5% of the compost to commercial growing media (95%)
significantly increased plant growth. Dr. Clive
Edwards, Ohio State University, Nursery Management
& Production, January 1995
- Research has shown that twice as many roots
grew in pure worm castings than in sphagnum. Dr.
Clive Edwards, Ohio State University
- Many species of earthworms actually eat the bad
microbes (fungi, bacteria, etc.) that are plant
pathogens and in the process they also increase the
good beneficial microbes.
- It has recently been discovered that in
feeding, earthworms consume spores of mycorrhizae,
a beneficial fungi that help roots take up
nutrients. These spores are deposited in the worm
castings, deep in their burrows, where roots easily
find them as they grow. The Avant Gardener, p. 87,
- Studies have shown that earthworms can increase
barley yields 78-96%, spring wheat and grass yields
400%, clover yields 1,000%, and peas and oats by
70%. Other studies found that yields were increased
for millet, soybeans, lima beans, and hay. Studies
in New Zealand found that earthworms at least
doubled yields in all cases and adding worms to
crops has become standard agricultural practice.
Earthworm Ecology and Biogeography in North
- Experiments at Tennessee Technological
University found that 10% vermi-compost in a
potting mix improved the germination of seeds of
low viability (Echinacea purpurea) by 43%
- Researchers at Oregon State University have
found that a tea made from the worm castings speeds
up the sprouting of hard to germinate seeds
following just one hour of pre- soaking.
- A large earthworm population suppresses weed
- The tunneling activity of earthworms prevents
many of the conditions that weed seeds need to
- Earthworms often eat weed seeds and either
destroy them or reduce their ability to
- Earthworms stimulate the growth of
microorganisms in the soil and some weed seeds are
destroyed by these microorganisms.
- Some microorganisms (bacteria and fungus whose
growth is stimulated by worms) live in a symbiotic
relationship with plant roots and help plants grow
better hence shading out weeds and out competing
them for water and nutrients.
- Worms often help clean up dangerous chemicals
in the environment
- Researchers have found that bacteria living in
the guts of worms breakdown (detoxify) many
hazardous chemicals such as hexachlorocyclohexane
(HCH), Organic Gardening, May/June 1993
- Microbes living in worms have the ability to
breakdown complex organic molecules like cellulose
- Improve water absorption and prevent
- Increase the water stability of the soil,
earthworm castings can take a direct hit by a
raindrop and maintain their shape, this reduces
erosion and runoff hence helps the soil absorb
- A research study conducted in Minnesota showed
that earthworms added to cornfields increased water
absorption rates 35 times over control fields
without the earthworms, within a 6 week period.
Acres USA, March 1994.
- Soil in a field with 100 nightcrawlers per
square yard, 2 inches of water (a very heavy
rainfall) could be absorbed by the soil in 12
minutes. The same soil without earthworms took over
12 hours to absorb that much water. National Soil
- If the top 3 feet of soil contained 25%
macropores (earthworm burrows) then that soil
should be able to absorb at least a 9 inch rainfall
without runoff. Natural Food & Farming,
- One study showed that on a sloping field with
no-till practices, there were 155 earthworms’
holes per square yard and an average runoff of 0.08
inches per year. This compares to a tilled field
with 6 holes per square yard and 4.9 inches of
runoff per year. The average rainfall for this area
is 39.4 inches. Natural Food & Farming,
- Scientists from the Agricultural Research
Service found that grass and leave mulched plots
had twice as many earthworms as those mulched with
cornstalks. Water penetrated the earth-worm filled
soil up to 4 times faster.
- Chemicals produced in the earthworm cause the
castings to form aggregates in the soil that are
resistant to erosion.
- Studies have shown that earthworms in soils can
easily triple infiltration rates and cut run-off in
half. Earthworms in Agroecosystems, 1995.
- Some scientists now believe that earthworms
have the potential to eliminate soil erosion
- This could save society billions of dollars in
erosion control, reduce pollution from dangerous
synthetic chemicals and improve the
- In an acre of good soil researchers have found
more than 1 million worms and 1,200 miles of
earthworm holes or burrows.
- Earthworms are valuable
- One-million earthworms per acre is about 25
earthworms per square foot of soil. If one had 1
nightcrawler per square foot at a value of $1.00
per dozen then one would have $3,630 worth of
earthworms. Full retail value of one million
earthworms would be over $83,000. If earthworms
would work only 100 days per year and eat their
weight of soil and/or residues daily, then at that
rate with one ton of earthworms per acre you would
have 100 tons of earthworm manure (castings) per
acre per year. This is about 2/3 inch deep layer
over an entire acre of land. Natural Food &
Farming, July/August 1991.
- One million earthworms will have burrows which
will have the equivalent space of 4,000 feet of 6
inch drain tile. At a installed price of $1.20 per
foot for drain tile, those burrows are worth $4,800
per acre. Natural Food & Farming, July/August
- Soil samples from a field not fertilized for 5
years but with a active earthworm population was
analyzed. Based on the reported analyses it was
found that 100 tons of earthworm castings will
contain 4 lbs. of nitrate nitrogen, 30 lbs. of
phosphorus, 73 lbs. of potassium, 90 lbs. of
magnesium, 500 lbs. of calcium. That is the
equivalent to a 4-69-86 fertilizer and 3/4 ton of
limestone worth $34.15 per acre with no fee for
spreading or transportation.
- Research presented at the ISEE 5 (International
Symposium on Earthworm Ecology at Ohio State
University) point at earthworms being a important
biomedical resource. It has been found that
ingredients from earthworms have anti-cancer
- The bodies of earthworms are extremely nutrient
rich from minerals to amino acids, proteins and
vitamins. When earthworms die these nutrients are
released into the soil.
- How to attract and promote earthworms
- Mulch all soil with organic mulches which help
stabilize soil temperature and moisture. Earthworms
love Native Mulch and grow big and fat in it.
- Mulch provides food and shelter for earthworms.
Compost is an excellent mulch and as a soil
amendment to attract (food source) earthworms.
DO NOT USE DANGEROUS SYNTHETIC CHEMICALS:
- Agricultural chemicals such as salt based
artificial fertilizers (i.e. 13-13-13), pesticides,
etc. can kill earthworms. Even if a few pesticides
do not kill earthworms, such as DDT, birds are
killed when they eat the worms. Pesticide Reviews,
Vol. 57, 1975.
- Earthworms and other beneficial organisms are
destroyed by synthetic chemical fertilizers and
fungicides, pesticides, etc. (Reviews of
Environmental Contamination and Toxicology, 1992).
In the absence of earthworms, the soil becomes
lifeless, sterile, nutrient deficient and develops
lots of problems.
- Studies have found that most organic
fertilizers tend to have a positive effect on
earthworms and increase population densities.
Earthworm Ecology and Biogeography in North
- Soils that are not tilled have 3-4 times as
many nightcrawlers (surface feeding earthworms) as
soils that are tilled in the spring or fall.
Tilling greatly accelerates the breakdown of
organic matter in the soil that worms need.
National Soil Tilth Lab
- Studies have shown that mulches produced from
grass cuttings or leaves have twice the earthworm
population than course mulches from straw or corn
stalks, etc. National Soil Tilth Lab
- Mulches made from wood wastes that have lots of
"fines" or small particles sizes are
easier for worms to use (swallow and eat). The
increased particle surface area of the small sizes
also allows for greater microbial activity that is
preferred by worms.
- Rough (unfinished) compost is one of the best
worm-food mulches there is. The Avant Gardener, p.
- Types of earthworms, Over 3,000 worm species have been identified.
Experts disagree as to what distinguishes one type
of worm from another and if one species is a true
earthworm or not. All soil worms are beneficial and
most references lump all soil worms into the
category of "earthworms".
- Two basic types of worms, those that feed on
the surface and those that feed in the subsurface.
The surface feeders eat plant residue, are
generally large worms and live in vertical burrows
often over 6' deep. Subsurface feeders are
smaller than surface feeders like nightcrawlers but
outnumber them 9 to 1. They eat their way through
the subsurface loosing, aerating and improving soil
structure in the process.
When worms are separated into "worms"
and "earthworms" then following
- Redworms, often called manure worms, brandling
worm, or red wigglers, they are reddish brown in
color, and they live in the soil in the surface
layer of decaying vegetation (litter). They feed on
this layer, multiplying rapidly in numbers, expand
into poorer surrounding soil and die thereby
distributing the nutrients contained in the excess
wastes over a larger area. Often used in small
scale worm bins. Eisenia foetida and Lumbricus
rubellus (tends to be more soil dwelling if large
amounts of organic material are in the soil) are
examples of redworm species.
- Earthworms, often called soil processing worms,
they are a burrower, a soil processor, eating dead
organics and rock particles, grinding and excreting
them as a finely ground mix which serves as food
for bacteria. They tend to survive in harsh
conditions better than redworms. They do not
assimilate the organics to the same extent as
redworms for themselves; hence they do not multiple
as quickly as redworms whose assimilation rates are
much higher. The higher rate of assimilation
(redworms) means that the nutrients consumed by the
redworms goes into building their own biomass while
the earthworm passes on these nutrients in a
soluble form in their castings.
- Pheretima elongata, deep burrowing earthworm
used in Bombay India to convert garbage into
vermicompost. Recommended by Uday Bhawalker
(Bhawalker Earthworm Research Institute) as the
most efficient organic waste converter. Waste
conversion occurs at the soil surface, not in a bin
hence less material handling is required.
- Lumbricus terrestris, called nightcrawlers, dew
worms, rain worm, orchard worm, etc. They like soil
temperatures less than 50EF. They are also dig
burrows and do not like to have their burrows
disturbed. They come to the surface to feed on dead
grass leaves etc. drawing them into their burrow
hence taking organic matter deep into the soil
layer. A good garden worm.
- Garden worms, Allolobophora caliginosa, A.
chloritica, Aporrectodea turgida, A. tuberculata,
etc. often found in pastures.
- Most worms found in U.S. soils are not
- Some earthworms from the southern hemisphere
can grow 3-5' long, 1" in diameter and
weigh up to 1.3 pounds
- Earthworms have many uses from soil farmer to
food for animals. Most recently they are being used
as a diagnostic tool since they have the ability to
hyper accumulate toxins and environmental
pollutants found in the soil (since they ingest
soil). As a result they are often collected and
their tissue analyzed for chemical contaminants
- Earthworm Math
25 earthworms/sq. ft. = 1 ton of worms/acre
1 ton worms = 100 tons of castings or b"
manure (castings) on surface per acre
Macropore equivalent to 4,000 ft. of 6" tile
drain pipe per acre
Nutrients added to 1 acre of soil each year:
4 lbs of nitrate of nitrogen
30 lbs of phosphorus
72 lbs of potash
90 lbs of magnesium
500 lbs of calcium
or in terms of a fertilizer analysis = 4-68-96
plus 3/4 ton of limestone for a nutrient value of
$34.15/acre in 1998.
- WORM SPECIES:
- Allolobophora chlorotica - the green worm, native to U.S.
- Aporrectodea rosea - the pink soil worm, native to U.S.
- Aporrectodea trapezoides - the southern worm, native to U.S.
- Aporrectodea turgida - the pasture worm, native to U.S.
- Bimastos tumidus - often found in compost piles, tolerates medium C:N ratios and cooler
temperatures better than Eisenia foetida , multiplies rapidly in old straw and spoiled hay,
hardy to Z-5 and will survive in ordinary soil conditions hence once established it would
survive without extensive preparations. Earthworm Ecology and Biogeography in North America
- Chumiodrilus zielae:
- Eisenia foetida: (the tiger or brandling worm), often used for composting sometimes called E.
andrei, (composter or surface worker species)
- Eudrilus eugeniae: (African nightcrawler) do well but cannot withstand low temperatures,(composter
or surface worker species)
- Hyperiodrilus africanus: (west African)
- Lumbricus rubellus: (common redworm or red marsh worm), used in Cuba's vermicomposting
program, (composter or surface worker species), native to U.S.
- Lumbricus terrestris: nightcrawler, native to U.S.
- Millsonia anomala:
- Perionyx excavatus: (Asian species) do well but cannot withstand low temperatures. (composter or
surface worker species)
- Octolasion tyrtaeum - woodland white worm, native to U.S.
- Pheretima elongata: bigger, stronger and livelier than common species such as red worm (esienia foetida). It is a deep
burrowing worm. Recently found in Missouri. Agricultural Research Service scientists are attempting to breed and spread this species as it
would be useful for breaking up hardpans and for erosion control (increase infiltration). Avant Gardener, p.87, 1995.
- deep burrowing earthworm: used in Bombay India
to convert garbage into vermicompost. Recommended
by Uday Bhawalker (Bhawalker Earthworm Research
Institute) as the most efficient organic waste
converter. Waste conversion occurs at the soil
surface, not in a bin hence less material handling
- Polypheretima elongata:
- Ponotscoex corethrurus: (common through-out humid tropical zone)
- Pontoscolex corethrurus:
- Stuhlmannia porifera:
- Earthworm predators:
- Artioposthia triangulata - "flatworm",
from New Zealand, destroying earthworms in Great
Britain, worm is dark brown, flattened with cream
speckled margins, likes moist conditions with
moderate to cool temperatures.
- Australoplana sanguinea - "flatworm",
from Australia, destroying earthworms in Great
Britain, tolerates warmer and drier conditions
than A. triangulata
The Earth Moved, by Amy Stewart, Algonquin Books,
P.O. Box 2225, Chappel Hill, North Carolina 27515
The Biology of Earthworms, C.A. Edwards and J.R.
Earthworms, K.E. Lee
Worms Eat My Garbage, Mary Appelhof, ISBN
Worm Digest Magazine, P.O. Box 544, Eugene, OR
The Farmer's Earthworm Handbook: Managing Your
Underground Moneymakers, David Ernst, Lessiter
Publications, Brookfield, Wisconsin. 1995.
"Worm Wise News", International Worm
P.O. Box 900184, Palmdale, CA 93590
Soil Biology & Biochemistry, Special Issue: 5th
International Symposium on Earthworms Ecology, ISSN
Earthworm Ecology, Soil and Water Conservation
Society, Edited by Clive Edwards, PhD, St. Lucie
Press, Copyright 1998, ISBN: 1-884015-74-3
SOURCES OF WORMS:
Twin Oaks Farm (Georgia Brown Nose...a heat tolerant worm)
Rt. #1 Box 78A
Purdon, Tx 76679-9801
Rabbit Hill Farm
Rt. 3 Box 2936
Corsicana, Tx 75110
City of Grapevine
Pat's Worm Ranch (Louisiana Wigglers - soil
worm..not for containers)
Sonny or Pat Kellum
P.O. Box 3194
San Antonio, Tx 78211
Brown's Worm Farm
Marietta, OK 73448
Flowerfield Enterprises (good source of educational
material for children)
Mary Appelhof ("The Worm Lady")
10332 Shaver Road
Kalamazoo, MI 49002
Rt. 2 Box 183
Eudora, AR 71640
Southern Worm Enterprize
12118 Marilyn Lane
Hammond, LA 70403
Willingham Worm Farm
Rt. 1 Box 241
Butler, GA 31006
(800) 223-WORMSOURCES OF WORM BINS
Gardener's Supply Company
128 Intervale Rd.
Burlington, VT 05401
5100 Schenley Pl.
Lawerenceburg, IN 47025
Peaceful Valley Farm Supply
P.O. Box 2209
Grass Valley, CA 95945