EARTHWORM
CASTINGS
Literature
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by Jim Jensen, YELM Earthworm & Castings Farm, 1997 yelmworms@aol.com. Permission granted to copy or post with
complete attribution in whole, without addition, deletion, or substitution.
Earthworm
castings provide
many special benefits beyond what farmers or gardeners can expect from just
manure or compost. In fact, most
specialists recommend that castings be used as a top dressing or
supplement. In this way, castings help
make the most effective use of all your bulk soil amendments. "A little goes a long way" because
the benefits of castings are so concentrated.
In
nature, composting worms tend to be highly localized, thriving in pockets of
highly enriched, organic materials.
They will consume a great variety of organic wastes and excrete
"worm castings" a highly valued soil conditioner. Composting worms also tolerate a wide range
of environmental conditions, which helps explain their adaptability.
Here
are the results of research conducted by leading researchers around the world:
·
“Scientific
studies show that worm-worked composts have better texture and soil-enhancing
properties; hold typically higher percentages of nitrogen, potassium, and
phosphorous; and may offer plants disease-fighting properties.” [Edwards, 1988].
·
"Earthworm
excreta (castings) are an excellent soil-conditioning material with a high
water holding capacity and a natural time release' for releasing nitrogen into
the soil." [Harris, et. al.,
1990].
·
“Vermicompost
(castings) is a finely divided peat like material with excellent structure,
porosity, aeration, drainage and moisture-holding capacity." [Dominguez, et. al., 1997]
·
"Among
the blessings of castings, vermiphiles count a smaller particle size than
thermophilic compost, lower odor, enhanced microbial activity, and as a bonus,
the vermicompost often contains worm cocoons, meaning a free work force for the
future." [Riggle and Holmes, 1994]
·
"Through
vermicomposting the humic substances showed an increase of 40 to 60 percent
which was higher than the value obtained for the composting process." [Dominguez, 1997]
·
“An
important feature is that during the processing of the wastes (manure) by
earthworms, many of the nutrients they contain are changed to forms more
readily taken up by plants, such as nitrate nitrogen, exchangeable phosphorus
and soluble potassium, calcium, and magnesium.
The most surprising result [of our research] was that even 5% of
worm-worked animal waste in the worm-worked waste/commercial mixture had a
significant effect on the growth of plants." [Edwards and Lofty, 1977]
·
In a
study for the EPA, researchers reported, "Passage of organics through the
earthworm's gut significantly alters the physical structure of the
material. Large particles are broken
down into numerous smaller particles, with a resultant enormous increase in
surface area. As a result of the
increase in surface area, any remaining odor-producing sulfides are completely
oxidized, microbial respiration is accelerated by a factor of 3, and Salmonella
bacteria are destroyed at a higher rate" [Camp, Dresser and Mckee, 1980],
·
“The
results obtained for the germination index showed a beneficial effect of
earthworms and the highest values of this index were recorded at the final
stages of the process. The germination
index was 65 to 70 percent higher in the treatments with earthworms than in the
control (no earthworms)."
Regarding heavy metals: "We
found a decrease of between 35 percent and 55 percent of the bioavailable metals
in two months." [Dominguez, 1997]
·
"By
shredding organic matter and contributing nitrogen, earthworms stimulate
microbial decomposition. Soil
microorganisms live in the worm's gut as well as the surrounding soil and so
the microbial content of casts is usually more concentrated than in surrounding
soil. Microbial activity in casts improves
soil structure by encouraging aggregation of particles. Microbial secretions (gums) and growth of
fungal hyphae stabilize the worm cast.
Worm-worked soil is relatively water-stable and will resist soil
compaction and run-off due to rains.”
[Edwards and Lofty, 1977]
·
“In
sum, earthworms must be seen not as a ‘miracle pill,’ a panacea for better soil
and crop yields, but as an integral part of intelligent organic soil management
practices. As earthworms are dependent
upon organic matter for food, and mulches for protection from heat cold, and
drought, so do growing plants depend upon the earthworm, in combination with
bacteria and other microorganisms, to maintain and improve soil structure and
fertility. When earthworms are seen as
part of a living soil, existing in and contributing to a vital ecosystem, then
the question of "whether earthworms create good soil, or good soil creates
earthworms" becomes essentially meaningless. Our aim is to improve our soils and grow higher yields of healthy
crops, not to banter about academic questions.
In this pursuit, the earthworm has-beyond doubt-found a treasured place
in the organic scheme of gardening and farming." [Minnich, 1977]
Buchanan,
M.A., et. al., "Chemical Characterization and Nitrogen Mineralization
Potentials of Vermicomposts Derived from Differing Organic Wastes," Earthworms
in Waste and Environmental Management, The Hague, Netherlands, SPB Academic
Publishing, 1988.
Camp,
Dresser, McKee, lnc~, Compendium on Soild Waste Management by
Vermicomposting, Cincinnati, OH, Municipal Environmental Research Lab, EPA,
1980.
Dominguez,
Jorge; '”esting the Impact of Vermicomposting," BioCycle, April
1997.
Dominguez,
Jorge; Edwards, Clive; and Subler, Scott; "A Comparison of Vermicomposting
and Composting," BioCycle, April 1997.
Edwards,
Clive, "Historical Overview of Vermicomposting," Biocycle, June
1995.
Edwards,
Clive, ed., "Breakdown of Animal, Vegetable and Industrial Organic Wastes
by Earthworms" Earthworms in Waste and Environmental Management, The
Hague, Netherlands, SPB Academic Publishing, 1988.
Edwards,
Clive, and Lofty, J.R., Biology of Earthworms, Chapman and Hall, London,
1977.
Frank,
Richard, et. al., "Metal Transfer in Vermicomposting of Sewage Sludge and
Plant Wastes," Bull. Environ. Contam. Toxicol, 1983.
Haimi,
J. and Huhta, V., "Capacity of Various Organic Residues to Support
Adequate Earthworm Biomass for Vermicomposting," Biology and Fertility
of Soils, Spring-Summer, 1986.
Harris,
George, et al., "Vermicomposting in a Rural Community," Biocycle, Jan.1990.
Loehr,
Raymond, et. al., Waste Management Using Earthworms: Engineering and
Scientific Relationships (final project report), Washington, DC, National
Science Foundation, 1984.
Minnich,
Jerry, The Earthworm Book, Rodale Press, Emmaus, PA, 1977.
Riggle,
David and Holmes, Hannah, "New Horizons for Commercial Vermiculture,"
BioCycle, October.
Scott,
Margaret, "The Use of Worm-Digested Animal Waste as a Supplement to Peat
in Loam less Com posts for Hardy Nursery Stock," Earthworms in Waste
and Environmental Management, The Hague, Netherlands, SPO Academic
Publishing, 1988.