Green Manure/Cover Crops Systems

(forwarded from John Jackson)
Chapeco, Santa Catarina State, Brazil  April 6-12, 1997

        In South America, 8 million hectares of farmland are in crop rotation, cover
crops, no tillage and direct seeding system.   There are about 5 1/2 million
hectares under this system in Brazil.  There are 3 million hectares in
Argentina, half a million hectares in Paraguay, 100,000 hectares in Chile, and
around 20,000 hectares each in Bolivia and Uruguay.   Rolf Derpsch, the Project
leader of the GTZ Soil Conservation Project, shared these estimates with me. in
        In Santa Catarina State in southern Brazil, the small farmer practitioners we
visited owned their farms.  Their farms were between 7 to over 30 hectares in
size.  They had access to farm machinery.  They were relatively prosperous
(they owned livestock, a small, neat bungalow home, one car or truck, satellite
dish).  They were cultivating cash crops like tobacco, and integrated into an
apparently stable market for agriculture produce.  They were descendants of
immigrants from either Germany or Italy.

Brazil Farm Visits
        We visited farmers who had managed to integrate a combination of crop
rotation, cover crops, no tillage and direct seeding technologies into the way
they farm.  There was more than one reason that motivated these farmers to
apply these combination of technologies.
        One, the use of cover crops checks weeds and apparently reduces labor costs
for weeding.  Interestingly, during the farm visits it was the smaller farmers
using animal traction and cultivating sloping farms who appreciated this
contribution of the cover crops.  In the municipality of Sao Joao Batista
inside the Ribeirao Fernandes micro-watershed, Mr. Joao Jacinto owns a 7.4
hectare flatland farm.  He integrated mucuna cover crop with corn as the means
to manage weeds.  Once, he incorporated the mucuna into
 the soil but this resulted in a tremendous weed problem.  That experience
convinced him that a permanent cover was better.
        Two, mucuna cover was as a management practice for heavy clay soils.  Mr.
Milton Amorin, farms a 6.75 hectare of flat farm land also in the municipality
of Sao Joao Batista.  He maintains a mucuna cover to prevent the heavy clay
soil on his farm from sealing and becoming very hard during the summer.  This
is an important practice for Milton who uses animal traction.
        Three, tobacco is an important cash crop in the communities we visited.
Introducing cover crops into tobacco farms improves the quality, though not
necessarily the quantity of tobacco harvest.  It is the improved quality that
fetches the better selling price.  Roland Ristow has been rotating corn and
tobacco, and planting mucuna as a cover crop for the past 40 years on his farm
in the municipality of Ibirama.  Mr. Ristow harvests 25,000 kgs of tabacco per
hectare, using half the chemical nitrogen input hi
s neighbors use, together with mucuna.  Average production in the area is
17,000 kgs per hectare.  In Sao Joao Batista the tobacco companies provided
farmers with the first seeds of mucuna.
        Four, five farmers we visited integrated the combination of crop rotation,
cover crops, no tillage technologies with cattle and swine enterprises.  Nilton
Amorim has been giving a home made mucuna feed mix to about 10 heads of cattle
for the last 5 years.  He uses a mechanical grinder to process dry mucuna
seeds.  He mixes a third of ground mucuna with two thirds of other foodstuff,
such as corn.  Joao Jacinto feeds mucuna to fatten young animals and nourish
milking cows.  He gives 3-4 kgs of green mucuna
seeds to each cow per day.  He also cooks mucuna seeds and gives to fish in his
fishpond.  Ernesto and Roland (father and son) Ristow, were feeding mucuna
seeds to their pigs (but I did not find out if and how they process the
mucuna).  In the municipality of Agrolandia, inside the Ribeirao Das Pedras
micro-watershed, Mr. Alvim Trappi owns 19 cows.  By planting a mix of oat and
vetch as a cover crop with corn, he gets feed for his cattle in the winter with
the regrowth serving as a winter cover.  I think it
 is Mr. Trappi who had experimented, with success, in feeding directly mucuna
pods to cattle.  Mr. Aurima Knauls integrated a family enterprise of about 100
breeding sows with a corn and cover crop system in a 19-hectare farm.  The
contribution of the cover crop to the pigs is indirect as the maize is the main
source of foods for the animals.
        Finally, Joao Jacinto was planting mucuna because there was market for the
seeds in his village.  The mucuna seeds fetched a price of  $ 0.80 per kgs,
which was more than the price of edible field bean at $ 0.50 per kgs.  But Joao
also said that farmers not planting mucuna are those who want two field bean
crops per year, therefore leaving no room on the farm to plant mucuna.
However, my impression is that this was an artificial market created by
EPAGRI's vigorous promotion of mucuna.
        At the farm level, the farmers above have improved their livelihoods by
integrating cover crops into their farms and farm enterprises.  At the
community level, according to Ken Schlather (Cornell University agronomist),
there is some data showing reduced siltation in the dams located in the
micro-watersheds where EPAGRI is working.  The apparent widespread adoption of
permanent cover cropping in the area may have something to do with this.  There
may also be a reduction in the use of herbicides inside the
micro-watersheds.  Farmers using cover crops and no-tillage systems are
applying fewer herbicides than farmers who do not apply these practices.
        The weakest link in the cover cropping, no-tillage technology in South
America, in my opinion, is its dependence on the use of herbicides.  The great
majority of farmers applying the cover crops, no-tillage technologies still
find that they have to apply herbicides -- though at lesser amounts -- to
manage the cover crops ground cover.  Rolf Derpsch said that there are a few
exemplary farmers who have made the transition to doing away completely with
using herbicides.  Two important factors enable these far
mers to manage weeds without having to use herbicides.  One, the availability
of farm implements that allow the farmers to harvest the main crop and plant
the cover crop simultaneously.  This encourages early establishment of the
cover crop and checks outbreak of weeds.  Two, availability of farm labor to do
spot weeding as a management practice.  Apparently some farmers, especially
those just starting to practice cover cropping, no-tillage technologies, are
not very confident that the ground cover can thor
oughly check outbreak of weeds.  This is one reason why they continue to use
herbicides.  The herbicide being used widely in Brazil is Round Up.

        The Central America and Mexico case studies shared some recommendations based
on critical reflection on what small farmers have done with the cover crops
technology over the years and why.  A recommendation with a lot of consensus
was to develop cover crops that can provide food for people or animals, and has
economic value.  The lack of these characteristics was constraints to wider
adoption of mucuna and canavalia among resource poor farmers.  The Mexico case
study recommended that research look beyond c
over crops/green manures in addressing sustainability of small farms in the
region.  Farmers who had experimented with cover crops, according to the Mexico
case study, had both positive and negative impressions about their usefulness.
Both Central America and Mexico acknowledged the benefits of cover crops as a
regenerative agriculture technology.  They also cautioned, and recognized, that
in several cases the NGOs and researchers are often more enthusiastic about
cover crops than the farmers are.

        In a place like southern Brazil, the environmental, economic, political and
social conditions do not seem to be constraints to family farms.  Therefore a
technical intervention such as cover crops has made and apparently continues to
make significant positive impact on the livelihood of farmers and on the
environment.  In Central America and Mexico, where the external environment is
less favorable to small farms, a similar technical intervention has made less
ground.  In such a setting, it may take more th
an just a technical intervention to benefit a lot of small farmers.

May 4, 1997
John Jackson
World Neighbors, Philippines

"New Generation Cropping Systems": the cutting edge of sustainable agriculture
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Cedar Meadow Farm
679 Hilldale Rd
Holtwood PA 17532  USA
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