|
Worldwide Portal
to Information on Soil Health |
English
|
 |
 |
 |
 |
 |
|
|
|
|
 |
|
 |
|
|
|
|
|
|
|
|
Coberagri-L (Year 2000)
(CIDICCO's Spanish language electronic discussion group)
-return
to main gmcc discussion archives menu-
English summaries of Spanish traffic
- cover crop - green manure - mulches -
(go to 2001 discussions)
|
|
|
|
|
|
|
|
|
Cover crops for highland areas:
Brian Sims from the Institute for Research in Silsoe, UK wrote in response
to a request for information on cover crops for semi-arid areas (1/00),
to offer that some of the information from work in Inter-Andean Valleys
of Bolivia would be available upon specific request. A related discussion
was that on cover crops for soil compaction in semi-arid highlands, which
began with a question from Bernard Triomphe (2/00) on crops such as forage
radishes that might be helpful in relieving soil compaction in the highlands
of Oaxaca and Puebla, Mexico (1600-2200 masl, 500 mm rain) Luis Fregoso
wrote back to recommend that Sorghum Sudan Grass and annual ryegrass had
performed well in anti-compaction trials in Cornell University; Sorghum
Sudan Grass had a number of other beneficial aspects such as rapid biomass
production, forage quality, and also weed and nematode suppression.
Roland Bunch wrote (5/00) describing the multiple benefits of white sweetclover
(Melilotus alba) for high, semi-arid areas. In Oaxaca, Mexico this
cover crop is known as a drought-resistant forage, suitable for intercropping
with maize, and tolerant of the poor soils there. The problem encountered
in this region by farmers was that sweetclover was too resistant and could
not be gotten rid of when going to the next crop in a rotation without
resorting to herbicides. However, farmers had discovered that cutting
the plants at the soil line at the beginning of the dry season reduced
the persistence of the crop and eliminated this problem. Sweetclover thus
appeared much more promising than before. Francisco Guevara also wrote
from Oaxaca to tell about the experience of a farmer group, CEDICAM, in
growing and promoting sweetclover. In addition, farmers were also working
with choreque which appeared to be a variety of Vicia sativa, (in
contrast to in Central America where choreque refers to Lathyrus nigrivalvis).
Francisco also wondered whether there would be interest on the part of
researchers in documenting these practices. Another participant agreed
that sweetclover had been excellent as a sheep forage as well as for yield
improvements in corn on plots that had been previously in sweetclover.
There had also been opinions both ways among farmers on the ease of getting
rid of the sweetclover.
A request came to CIDICCO in July 2000 from Freddy Sanchez asking for
information on promising cover crops for highland areas of Costa Rica.
Milton Flores wrote back with information on CIDICCO's trials with indeterminate
varieties of Phaseolus lunatus (common bean), Phaseolus coccineus
(runner beans) and a variety locally called chilipuca, which seemed
to be a type of Phaseolus lunatus. These seemed adapted to 1500-1800
masl and also were double purpose, in being cover crops that also produced
a food product. Tephrosia is a shrub species already in use as an intercropped
shade plant in highland coffee plantations of Guatemala and Honduras and
is also being studied by CIDICCO. Also, Lathyrus spp. (probably
sativus also known as grass pea) seemed to be very promising for the high-altitude
niche, for breaking pest cycles in maize-potato rotations and for unsurpassed
biomass production among legumes. The only limitation early in the study
seemed to be that during the harvest period, with heavy dew and moisture
in the plantings, there was rotting of the pods. It was hoped that by
adjusting planting and harvest dates with respect to the dry season this
problem could be avoided.
Cover-crop/plant-parasitic nematode interactions.
See also the 2001 discussion
on high elevation cover crops.
Plant-parasitic nematode hosting and/or suppression by legume cover crops:
A question about plant-parasitic nematode hosting and/or suppression by legume cover crops (1/00) generated a discussion about these characteristics and the sometimes conflicting reports about nematode-cover crop interactions. For Mucuna and forage peanut (Arachis pintoi), some data suggests that these are hosts while other information contradicts this. Jose Araujo wrote from Chiapas, Mexico to say that he had seen damage from Meloidogyne (root-knot) nematodes in Canavalia, Cajanus cajan (pigeon pea), and a few varieties of Vigna unguiculata (cowpea); symptoms became especially severe during pod fill of these legumes. David Thurston wrote with an extensive list of references on the subject (in English), including information that Mucuna (velvetbean) was anywhere from somewhat resistant to suppressive of Meloidogyne species; several studies showed reduction of nematode levels with exudates from the velvetbean plants, and recommendations that velvetbean was an excellent rotation crop for annual cropping systems in treatment of nematode problems. Roland Bunch asked whether there might not be issues of experimental design leading to the conclusions about Mucuna and other legumes being hosts or non-hosts to parasitic nematodes. Death, decay and mineralization of the cover crop might produce the nematicidal effect, whereas the plant would appear as a host during its lifetime. He noted that all the studies concluding such legumes to be nematode hosts had not looked at what happens after the death of the plant.
Mucuna as a forage/feed source for animals:
A question on various aspects of design of a trial of green manures as forages for pigs and cattle brought up the question of L-dopa, a substance that has been suspected of toxicity for some animals and a possible limitation of Mucuna as a forage/cover. Milton Flores responded to the list that problems with feeding of Mucuna had generally come up when it was used as a large proportion of the feed for certain livestock. These effects seemed to be especially severe in chickens at up to 30% of the total feed ration or in pigs at 100% of the feed ration when compared to soy flour controls. For ruminants, there were no adverse effects of feeding up to 100% Mucuna pods, either in terms of growth or milk production. These results are summarized in documentation from the Zamorano College of Agriculture, and there was to be a workshop on the use of Mucuna as food and feed in April of 2000 in Honduras, with the proceedings also in English. Milton later wrote (7/00) to announce the publication of these proceedings, and posted a short summary of the proceedings to the list.
Efforts to document and disseminate fallow/green manure/cover crop practices:
Roland Bunch wrote to the list (7/12) to summarize the efforts to date to characterize cover cropping/green manure systems that he, CIDICCO, and MOIST at Cornell had been carrying out. Already there had been more than 150 systems documented, using about 40 different cover crops. It also seemed that the number of cover cropping or fallow systems in use in any given area far exceeded those that had been characterized. There thus seemed to be a great deal of work still to do in describing and disseminating fallow and cover crop systems. Reinaldo Cardona wrote from Venezuela to mention a system in use there (maiz ajonjoli) where Crotalaria juncea is used as a green manure, and which he had studied for its effects on Macrophomina phaseolina (fungus that causes charcoal rot of maize). Milton Flores wrote to the list to encourage the description in sufficient detail of 200 more green manuring systems, along with the publication on CD-ROM of those already described. Jean Marc von der Weid wrote from Paraná, Brazil to offer collaboration in describing green manure systems in that area.
Organic control of aphids on cabbage
Also in April 2000, there was an exchange of several messages on organic control of aphids in cabbage in the lowland Comayagua zone of Honduras. A flour/water mix (dries and suffocates aphids) and a dilute solution of soap with garlic were suggestions from the list. Soap/garlic cannot be applied late in the season or it leaves a bad taste in the cabbage. Commercial potassium salts or "soaps", available in some parts of Central America, were also recommended.
Miscellaneous:
Raul Aleman wrote to post a bulletin from CIDICCO (number 11) on the multiple uses of Jicama in western Honduras (3/00)
During this period there were also several brief exchanges in which people offered cover crop seeds for sale.
A conversation on composting of coffee pulp (4/00) centered on the need to inoculate with soil or not. The conversation was conducted in English and appeared on Mulch-L.
Rida Weidenger wrote
to the COBERAGRI-L list to ask about Mucuna practices she had seen in
Ghana, in which after a number of years of Mucuna cropping, maize plants
were tall but pale, compared to plants in a control plot which were small
but deep green (micronutrients? --editors note)
Reinaldo Cardoa wrote (11/00) to ask whether cultures of Trichoderma
harzianum would be available for trial in Venezuela.
TropSCORE's
Worldwide Soil Health Information Portal
Send us e-mail: lhf2@cornell.edu
© Copyright 2002 by TropSCORE and Cornell University
Last updated: March 13, 2003
by the Development Team