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INTERNATIONAL AG-SIEVE (VOL VII, 1)



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INTERNATIONAL AG-SIEVE  Volume VII, number 1   (SOIL FAUNA)
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-  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:

Agsievefb.inbox@parti.inforum.org

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.


Sincerely,

Roger Bairstow
Communications Manager
Rodale Research Institute

                                           
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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 
difficult. 

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 
ameliorator.

Methodologies

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 
50-100 kg/ha/year.

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

manure.

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% 
larger.

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%.

Conclusion

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 
land;
%       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 
Project), ORSTOM

Contact:

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



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BOOK REVIEWS:



>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 
rich vermicompost.

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 
the operation.


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 
earthworms:
 
"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 
in the Tropics. Written for people working in the field in the developing 
world, the Ag-Sieve contains the technical information that the scientific 
community needs and the practical information the field worker can use, but 
does not require a Ph.D. or a dictionary to understand.

We link the work of the major agricultural centers, the insights of the 
farmer, the experience of the multidisciplinary development team, and the 
individual researcher into an eight page newsletter that highlights 
breakthroughs in sustainable agriculture. 

Our audience functions as an Information Exchange Network. Readers contribute 
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Recent thematic issues cover the latest in tropical forest products, training 
opportunities, seeds, biodiversity, urban gardening and vegetable systems, 
women in agriculture, and agroforestry.
 
For those interested in hard copies write to:

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