EARTHWORMS - The Benefits
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.
- the tunneling activity improves soil aeration, porosity, and permeability.
- increase moisture absorption and 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 1½
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 fields respiration during cold wet
winter-spring months are 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 _ of a
soils air-filled pores. 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 allows 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.
- help compost residues and waste products, bacteria in a worm's gut help
destroy harmful chemicals and breakdown organic wastes
- create fertile root channels - the mucus lining of abandoned burrows are
an excellent source of nutrients
- 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 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
- 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 Ogun State University have found that a tea made from the
worm castings speeds up the sprouting of hard to germinate seeds following a
1 hour 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 1 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.
