- Searching for the Suitable Soil
- Book Reviews: From Garbage to Garden
Raising Worms for Bait
Below are some more rough articles which will be included in the next issue
(Vol VII, 1) of the International Ag-Sieve. The purpose of this electronic
version of the newsletter is to send out the soon-to-be-printed articles to
you, the reader, in the hope that you will respond and comment on the contents.
Please send your suggestions to:
Once comments are read, stylistic changes are made according to suggestions,
and some individual remarks will be added to the printed version under our
Readers React column. I hope you enjoy this up-coming issue, and I look forward
to your reactions.
Rodale Research Institute
Searching for the Suitable Soil
A high level of endemism and limited ability for colonization are attributes
which give many earthworm species a narrow geographical distribution. Most
"native" species also have minimal tolerance for disturbance. All in all, this
makes the introduction of foreign species to certain agricultural lands
Scientist at ORSTOM have been studying techniques aimed at stimulating
earthworm activities within the soil. Together, with the Ecology Institute of
Mexico, Peru's INIAA/NCSU Yurimaguas Experimental Station, the University of
Rwanda and the Spain's Universidad Complutense, they have completed the first
stage of their macrofauna project. The project's purpose was to: 1) identify
native and peregrine (wandering) species of endogeic earthworms which can live
in cultivated soils with low-input annual crops; 2) quantify earthworms'
demographic parameters and their short-term effect on soil texture, soil
organic matter and nutrient release; and 3) evaluate during six successive
cropping cycles the effects of earthworms on plant production and parameters of
soil fertility. Their research has identified those earthworm species which
have the ability to withstand disturbances and perform their role as a soil
Field experiments were conducted in small, 0.28 to 1.5 m2 experimental units
isolated with nylon mesh or plastic sheets. These units were randomly treated
"with" or "without" earthworms and three different residue management systems:
1) no incorporation of crop residues; 2) incorporation of stubble mulch; and 3)
stubble mulch + legume green manure. These units were distributed within 400 to
600 m2 plots divided into blocks.
Identification of tolerant species
Native and exotic species were selected from a compiled database of 176
species and 60 communities from the tropical America (six countries) and Africa
(two countries) for their potential to adapt to annual crop conditions. More
peregrine species, as opposed to native endemic species, were selected.
Selection criteria were:
% tolerance of varying environmental conditions;
% time elapsed since the original ecosystem was disturbed;
% the type of agricultural practices applied to the area.
A comprehensive analysis of the demographic parameters of 14 tropical
earthworm species identified 3 types. Native species from Western Africa
(Lamto, Cte d'Ivoire) were found to have extended generation times (15-42
months), low fecundity rates (1.3-10.7 cocoons/adult/year) and long life
expectancies (3-12 months). Peregrine endogeic Pontoscolex corethrurus and
Polypheretima elongata had short generation times (3-4 months) and high
fecundity rates (35-100 cocoons). While native species from India had
intermediate demographic profiles.
Short-term effects on the Soil
Earthworms released significant amounts of mineral nitrogen and assimilable
phosphorus in their fresh casts. The amount of nutrients found in casts was
related to the mineralization rates in the original soil and the earthworm
species. The highest concentration of mineral-N (1095 mg/kg) was found in casts
of Pontoscolex corethrurus in an andosol of Martinique. The lowest
concentration (24 mg/kg) was measured in casts of Millsonia anomala in a
ferric acrisol in Cte d'Ivoire.
In the sandy soil at Lamto, Ivory Coast, mineral-N levels had dropped down to
control levels after eight days. In an ultisol at Yurimaguas, Peru, mineral-N
concentrations were significantly higher in casts than in a control soil after
16 days of incubation. Concentration of assimilable P was 50% greater in fresh
casts of Polypheretima elongata fed with a vertisol, than in the control soil.
Based on these results, the annual production of mineral-N in fresh casts of a
population of Pontoscolex corethrurus in a tropical pasture was estimated at
Settlement of introduced populations
Low densities of selected earthworm species were introduced in low input
cropping systems at Lamto, Cte d'Ivoire; La Mancha, Mexico and Yurimaguas,
Peru to test their effects on soil fertility in the field. After 5 cropping
cycles (i.e. two years) at Lamto, biomass of the native Millsonia anomala was
limited to a few grams fresh weight/m2 in the experimental units due to the low
nutritive quality of the soil. At Yurimaguas, earthworm biomass was sustained
at a much higher level (40g fresh weight on the average, with peak values of
>80 g) at harvests 2 and 3 in treatments receiving an application of legume
green manure. At the 5th harvest, biomass was significantly lower in the "no
organic input" treatment than in treatments with crop residues and legume green
Earthworms significantly affected soil structure. At Lamto and Yurimaguas,
earthworms increased soil macroaggregates and bulk density while infiltration
rates slightly decreased. N-depletion was somewhat delayed and the structure of
soil organic matter (SOM) into particle size fractions was modified. After five
crops at Lamto, more coarse organic matter in treatments with earthworms was
found. Microbial activities were also modified. N-mineralization rates were
higher during the early phases. At the fifth harvest, less nitrate was released
in soil from "with earthworm" treatments but microbial biomass was 10-40%
Plant production was significantly increased in 10 out of the 20 cropping
cycles observed at the three sites. At Lamto, soil was too poor to sustain a
sizeable earthworm population. Biomass decreased by a few grams/m2 at the third
cropping cycle. The effect on grain production was low (10-20%) and limited to
the first crop. At La Mancha, the biomass of P. corethrurus was 21-27g in
treatments with organic inputs and 10-12g in treatments without mulch. At
Yurimaguas, where the soil was relatively more fertile, the average earthworm
biomass for the first five cropping cycles was lower in the treatment with no
organic inputs (biomass of 30g fresh weight/m2 ), as compared to the treatment
with application of stubble mulch (40g) and the treatments with stubble +
legume green manure (50g). Grain production at Yurimaguas was much higher with
average increases of 145% in a continuous maize crop fertilized after the 3rd
harvest (-5% to +350% depending on the cropping cycle). In the traditional low
input rotation (-43-78%) the grain yield was 36%.
This study clearly pointed at the selective advantage of peregrine species for
use in arable systems. Their tolerance for a wide range of environmental
conditions, parthenogenetic reproduction and fast population turnovers make
them suitable for colonization purposes. Pontoscolex corethrurust is the most
commonly found earthworm, but Polypheretima elongata is another widely
distributed species with high potential for manipulations.
The introduction of earthworms into traditional low-input systems is
promising. Whenever sizeable earthworm populations have been created from the
original inoculum, significant increases of production were observed. It is yet
too early to know how sustainable introduced earthworm systems are. However, as
some farmers abandon their cropland after two or three cropping cycles (e.g. at
Yurimaguas), the introduction of earthworms which result in high increases of
production at that stage may be a good technique. As ORSTOM's director Patrick
Lavelle states, the key research issue is now to determine practices where
earthworms will be maintained at a critical level of biomass, estimated at
30-40 g fresh weight m2 of soil.
Based on the preliminary results of this study, research on earthworm
production techniques needs to address four critical issues:
% production of large quantities of earthworms for colonization;
% spatial and temporal colonization patterns of earthworms in arable
% comparative effects of earthworms on different species, grown in
different soil types;
% improvement of earthworm activities through the use of low quality
organic wastes which are not used normally in farming systems (sawdust, coir,
coffee wastes, etc.)
This study demonstrates the potential earthworm colonization can have on
arable lands, but also the need for more information. ORSTOM has started the
second phase of their macrofauna project which is intent on answering some of
these new questions.
Summary Report, Conservation of Soil Fertility in Low-Input Agricultural
Systems of the Humid Tropics By Manipulating Earthworm Communities (MacroFauna
P. Lavelle, Centre ORSTOM de Bondy, Laboratoire des Sols Tropicaux, 72 route
d'Aulnay, 93143 - Bondy Cedex, France Tel: 33 1 48 02 55 01 Fax: 33 1 48
47 30 88
>From the Garbage to the Garden
Prostomium, putrefaction, setae, toxoplasmosis and enchytraeids are just some
of the words used frequently by earthworm experts. Many times however, they are
words that can confuse and discourage a number of people from becoming involved
in vermicomposting. If you want to know what earthworms to use, or how many
earthworms you need to process x amount of waste, then read Mary Appelhof's
book, "Worms Eat My Garbage". As interest in vermicomposting has grown, so has
the importance of this book. It presents an easy-to-follow process of creating
your own earthworm composting system.
Even in its tenth printing, this book is hardly outdated. The book describes
the world of worms, the materials needed for your vermiculture project, and
continuously informs readers about the earthworms' relationship with soil
quality. Types of worm beddings, container size, temperature and labor
requirements and reproduction rates are some of the many relevant topics
covered. The book's simple approach to vermicomposting allows readers to
understand the basics and begin experimenting with their own composting system.
Included in this book are a useful glossary, a metric conversion sheet, a
personal record sheet for your own project, bibliographical references and
sources for further exploration into earthworm cultivation and composting. For
the earthworm novice, there is no better place to begin.
As Mary Appelhof explains, vermicomposting is a relatively simple process and
easily understood after a few basic principles and techniques are explained.
Upon reading her book, a reader can become the worm expert and composting
aficionado that he or she has always wished to be.
Appelhoff, Mary, Worms Eat My Garbage, Flower Press, c. 1982, pp.100, $8.95.
To Order: Flowerfield Enterprises, 10332 Shaver Rd., Kalamazoo, MI 49002
Tel: (616) 327-0108
Raising Worms for Bait
With only a minimal initial investment and a little work, anyone can start a
profit-making worm business, according to Earl B. Shields, author of "Raising
Earthworms for Profit". For those interested in raising earthworms to be sold
as bait or to be used in making vermicompost, this and other handbooks can help
make the venture easy and enjoyable.
"Raising Earthworms for Profit" is a comprehensive guide which details each
step involved in creating either a small- or large-scale earthworm-raising
enterprise. The guide begins by explaining the different kinds of earthworms
available, the expected number of earthworms after a year of breeding and the
benefits resulting from the worms' ability to build soil with a high organic
matter content. It also shows how rabbit raisers can combine their endeavor
with worm breeding, as worms are useful in processing rabbit droppings into
Planning the earthworm project, building indoor and outdoor bins, feeding,
protecting worms from their natural enemies, harvesting, packaging and shipping
worms, and necessary supplies for the operation are all discussed in detail.
Drawings, photographs and diagrams complement the text and enhance the reader's
level of understanding. The final section gives an annotated list of useful
books for further reading. For those who want to begin a profit-making
earthworm project, this guide provides a solid base covering major aspects of
Shields, Earl. 1994 (Nineteenth Edition). Raising Earthworms for Profit.
Shields Publications, 128 pages, $7.00.
The following handbooks are also useful for those with an interest in
"Earthworm Buyer's Guide 1994-95" -
This guide provides a listing of earthworm hatcheries in the USA and Canada.
Readers receive a state-by-state listing of suppliers and information on where
to buy bedding, bin, packaging and other supplies. Shields, Robert F. 1994.
Earthworm Buyer's Guide. Shields Publications, 63 pages, $5.00.
"Raising the African Night Crawler or Tropical Giant Worm"-
Raising this type of bait, which is known for its ability to withstand extreme
heat, can be easy and profitable. The guide provides specific information on
bins, bedding, feeds and feeding, harvesting, packing and shipping, and selling
the nightcrawlers. Morgan, Charlie. 1970. Raising the African Night Crawler
or Giant Tropical Worm. Shields Publications, 53 pages $5.00.
To Order: Shields Publications, P.O.Box 669, Eagle River, Wisconsin 54521
Tel: (715) 479-4810
The International Ag-Sieve is a bimonthly collection of gleanings of the
latest and most applicable information in the field of sustainable agriculture
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