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 Tilth Lab
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 75100% 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 castings.
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 America, 1995.
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 front end.
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 surrounding soil.
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. 262-264
Earthworms help eliminate thatch in lawns and grassy areas
by eating and digesting the plant debris.
Studies have shown that soils rich in earthworms have less
of the harmful nematodes like root feeders.
Earthworms create soil conditions that discourage populations
of soil organisms such as insects, nematodes and others that
are harmful to plants.
By passing soil and organic matter through their bodies, gradually
make acid soil less acid and alkaline soil less alkaline. The
Rodale Book Of Composting, 1993
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, 1995.
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 America,
1995.
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 growth
The tunneling activity of earthworms prevents many of the
conditions that weed seeds need to germinate.
Earthworms often eat weed seeds and either destroy them or
reduce their ability to germinate.
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 and lignin. Improve water
absorption and prevent erosion
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
water.
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 Tilth
Lab
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,
July/August 1991.
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, July/August 1991.
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 environment.
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 1991.
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 properties.
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 America, 1995.
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. 87, 1995. 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 applies:
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 native
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 is required.
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
USEFUL REFERENCES:
The Earth Moved, by Amy Stewart, Algonquin Books, P.O. Box
2225, Chappel Hill, North Carolina 27515 ISBN 1-56512-337-9
The Biology of Earthworms, C.A. Edwards and J.R. Lofty
Earthworms, K.E. Lee
Worms Eat My Garbage, Mary Appelhof, ISBN 0-942256-03-4
Worm Digest Magazine, P.O. Box 544, Eugene, OR 97440-9998
The Farmer's Earthworm Handbook: Managing Your Underground
Moneymakers, David Ernst, Lessiter Publications, Brookfield,
Wisconsin. 1995.
"Worm Wise News", International Worm Growers Association,
P.O. Box 900184, Palmdale, CA 93590
Soil Biology & Biochemistry, Special Issue: 5th International
Symposium on Earthworms Ecology, ISSN 0038-0717
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:
Texas:
Twin Oaks Farm (Georgia Brown Nose...a heat tolerant worm)
Jim McCarter
Rt. #1 Box 78A
Purdon, Tx 76679-9801
(817) 578-1272
Rabbit Hill Farm
Jay Mertz
Rt. 3 Box 2936
Corsicana, Tx 75110
(903) 872-4289
Earthworm Institute
City of Grapevine
Larry Wilhelm
(817) 424-0540
Pat's Worm Ranch (Louisiana Wigglers - soil worm..not for
containers)
Sonny or Pat Kellum
P.O. Box 3194
San Antonio, Tx 78211
(210) 922-1592
OTHER:
Brown's Worm Farm
Rosemary Brown
Box 284
Marietta, OK 73448
(405) 276-3897
Flowerfield Enterprises (good source of educational material
for children)
Mary Appelhof ("The Worm Lady")
10332 Shaver Road
Kalamazoo, MI 49002
(616) 327-0108
Jim Knight
Rt. 2 Box 183
Eudora, AR 71640
(510) 294-2603 Southern Worm Enterprize
12118 Marilyn Lane
Hammond, LA 70403
(504) 294-2603
Willingham Worm Farm
Rt. 1 Box 241
Butler, GA 31006
(800) 223-WORMSOURCES OF WORM BINS & OTHER INFORMATION:
Gardener's Supply Company
128 Intervale Rd.
Burlington, VT 05401
(800) 955-3370
Garden's Alive
5100 Schenley Pl.
Lawerenceburg, IN 47025
(812) 537-8650
Peaceful Valley Farm Supply
P.O. Box 2209
Grass Valley, CA 95945
(916) 272-4769