Minimum tillage for soi1 and water management with...
Minimum tillage for soi1 and water management with animal traction in
the West-African region
br
Alioune Fall’, and Adama Faye2
IAgricultural
Mechanisation, ISRAKRA Djibélor, 2Animal Scient& Coopération Suis$
I
,
Abstract
I
The paper reviews the utilization levels of animal traction for better soi1 and water management, through
conservation tillage in the West Aj?ica region. Various tools and techniques used by farmers are reported.
Recommendations
in order to improve .farmers’ environmental conditions for better agricultural productivity
and sustainability have been pro@sed. -
translate the farmers’ concern to reach sustainable
1. Introduction
cropping systems through decisions to be made on
when and how to conduct field activities in relation
Farmers in the West-Afiican region are mainly
to available resources (Jouve, 1986). However,
smallholders who must contend with increasing
there is a number of limiting factors on farmers’
population pressure on available land, low level of
performance which cari help explain their response
mechanisation, short fallow, permanent cropping
to the situation.
and risky rainy, seasons. The existing farming
systems seem to be vulnerable with regard to
A number of research studies, conducted both on-
continuous degradation of the farmers’
station and on-farm throughout the region, have
environmental conditions. Current practices have
shown that sustainability of cropping systems is
led to advanced soi1 erosion which has
better achieved when agricultural practices are
compromised productivity on both land and crops.
aimed ,at improving plant-soil-water relations.
Farmers depend greatly on animal traction for
1.1 Objective
energy supply to meet their agricultural production
objectivés. The energy provided represents more
The objectives of this paper are:
than 90% of the mechanical energy used in
agriculture in the area of study. The use of animal
(9
to review the use of animal traction in the
traction is viewed by Jaeger (1984) as an important
region towards better soil-water
step in creating more production opportunities and
management through conservation tillage,
increasing retums through better land preparation
and jmproved timeliness of field operations.
(ii)
to identify the most suitable tools and
However, the intensity of animal traction utilisation
techniques available to farmers and
in relation to the level of farmers’ experience is
highly variable fiom country to country.
(iii)
to formulate recommendations in order to
improve farm environmental conditions
Animal traction was introduced in Senegal, Guinea
for enhanced sustainability.
and Mali in the late 1920s and early 1930s. The
most significant impact of animal traction in
TO do SO, major research fïndings in relation to
today’s farming systems h?s been the increase in
major constraints to soil-water management, tillage
cultivated area per active household member rising
and trop growth are discussed. Most of the
fi-om 30 to 40% in Senegal and 40 to 70% in Mali.
researches on animal traction have been conducted
in Senegal, Mali, Guinea, Togo, Sierra Leone,
For the last two decades, agriculhual production
Burkina Faso, Niger, Nigeria and Tchad. However,
throughout the Sahel has been mainly bound by the
there is emphasis on research activities conduced in
shortage of rainfall along with its uneven
Senegal.
distribution during the rainy season. The amount
of rainfall has decreased by an average of 33 to
45%, inducing new farmers’ production strategies
towards meeting food security requirements
(Posner et al., 1988). The coping sbategies
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.. .
2. Climate and soils description
toposequence and the types to the texture of the
surface horizon. Sub-Saharan Aiïica was divided
2.1 Climates
into five large zones (Charreau, 1974):
The climatic transition in West Afi-ica takes place
-
In the northern part of Senegal, Mali and Niger
across a short distance between humid and dry
and Tchad: sand and dunes.
weather. In this short distance away from the
equator, the occurrence of two rainy seasons is
-
In the Niger Rive?s arc and in a great part of
observed. The dry spell between the two rain
the Tchad basin: alluvial deposits ranging Çom
seasons is short and cari vary in length in relation to
pure sand to fine clay.
the duration of the sun cycles. Vegetation in tbe
area corresponds to the humid forest. The high
-
West, South-West, and East’of the Niger
amount of rainfall has the tendency to create more
River’s arc in Burkina Faso, in two-thirds of
soi1 nutrients and leaching problems leading to
Senegal, and in Southem Tchad were found
fiagile and infertile soils. Soi1 protection is a must.
the Terminal Continental formations. The
materials generally went through a strong
As pointed out by Beets (1990), the weather around
ferralitic alteration.
the 15’ latitude is divided into two distinct seasons
in relation to occurrence of rains: dry season and
-
In the Southern part of Niger River3 arc, in
rainy season. The area where this climate prevails
the central part of Mali, and in the Western
is becoming narrower with the global pejoration of
part of Burkina Faso is a vast area of Combro-
the weather. Therainfall is still significant and
Ordovician sandstones overlanded by an
relati,vely reliable. It stretches from moist to forest
ancient “lateritic” iron pan.
Savannah with an average annual rainfall of
1000 mm. Water runoff is a serious problem as are
-
In the southem part of Mali, in Burkina Faso,
forest tires during the dry season. Fires are
in the central part of Tchad: crystalline shield
fiequent and cari burn completely the grass
made up of plutonic rocks, metamorphic rocks
covering and protecting the soil, leaving bare soi1
and volcanic rock”
surfaces to receive the first tropical rain events at
the beginning of the rainy season.
The soi1 map showed that large areas of the West-
Afiican region are occupied by grey and yellow-to-
Northward, the semi-arid to arid types of climate
beige ferragenous soils (Alfïsol), and by red
prevail in the central and northern part of Sahel
ferralitic soils (Oxisol). These soils are mainly
countries Çom Senegal to Tchad. The weather is
characterised by a field capacity of 15 to 20% v/v
dry and hot with one short rainy season. Rainfall is
and a wiltiuk point of 7 to 9% v/v. The oxic
unreliable as drought situations are always reported
horizon of the ferragenous and ferralitic soils are
from year to year in terms of mid-season droughts
mainly made of a mixture of three elements:
or dry spells during the rainy season. Many studies
kaolin, amorphous hydrated oxides (iron and
have showed difficulties encountered in finding
aluminium), and quartz. They are desaturated and
solution to the drought situations.
characterised by a low cation exchange capacities
(CEC) due to the presence of kaolinite, and by
Dupont (1986) and Sivakumur (1988) developed
having almost reached the end of weathering in
techniqu’es to predict the level of probability of dry
their evolution.
spells from the onset of rains to the end of the final
development stage of the cropr, grown at the farm.
The ferragenous soils (“sol beige”) present a sandy
to course loamy texture in the Upper horizon with a
2.2 Soils of West Africa
sub-angular blocky structure and a fine loam to fine
clayey texture in the deeper horizon with angular
The soils in the West-Afiican region have been
blocky structure. The ferralitic soils (“sol rouge”
surveyed for more than twenty years by teams of
or red soils) present some altïc characteristics with
Alïican and European soi1 scientists. Charreau
sub-surface horizons made of clay accumulation.
(1974) published the first m&t exhaustive soi1
Their texture and structure are similar to the grey
classification for the Sub-Saharan Ahica. This was
type. Other important types of soils are those
made possible by a team of IRAT and ORSTOM
located in dryer areas, mainly made of sandy
(France) soi1 scientists. The West-African soi1 map
texture and these soils represent a transition
was made of 12 classes subdivided into sub-
between ferragenous and vertisol types (Ducreux,
classes, groups and sub-groups, families, series and
1984).
types of soil. The family was composed of soils
originating f?om the same kind of parent material.
The characteristics of these soils are important for
The series related to the position of the soi1 on the
two main reasons:
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The key success to environmental and farming
-
the wetting and drying cycles in relation to the
system sustainability is to train smallholders to
aggregates and structure stability, and
become soi1 moisture managers by giving them
more insight on subjects like:
-
the hardening process (“prise en masse”)
taking place during the dry season and after
0
Animal-drawn implements selection with
intermittent rainfalls followed by dry spells
suitable working components.
during the rainy season.
?
Physical and mechanical characteristics of
For these reasons, the management of soi1 moisture
their soi1 types.
regime appears to be a critical issue for plant
growth in this part of Africa, especially at the
?
Soi1 moisture regime (infiltration, holdmg
beginning of the rainy season.
capacity).
Nicou (1975) bd studied these &VO combined
o
Consumption rate and vegetative development
characteristics which tend to confer to thesoils
of grown crops.
specific physical and mechanical behaviour. A
major fïnding, confirmed by Ducreux (1984) was
3.
Conservation tillage with animal traction
the fact that the low clay content in the Upper
horizon (8 to 12%) and the presence of kaolinite
Research activities on no-till, minimum tillage, and
are responsible for the tendency of the aggregates
later on conservation tillage with animal traction
to harden tbrough cementation during the drying
started in the early 1960s in many West tican
phase of the cycle.
countries. These activities were mainly conducted
on station until1979 when the shortage of rainfall
A texh&l index called ‘Hardening Index”, defined
and the drought situation induced significant
as the ratio of the clay content over the coarse
changes in farmers’ production systems. However,
fraction of the,soil (coarse silt + coarse Sand), was
conservation tillage could not be isolated fiom the
introduced to describe the physical be,haviour of the
broader practices of soi1 conservation. The
tropical soils. They found Chat there was a linear
baseline was to develop techniques that:
relationship between the hardening of the soi1
upper horizons and the HI index for soils studied in
(9
reduced the number of mechanised field
Senegal and Niger. The higher the HI index, the
operations,
higher the tendency of the soils to harden during
the drying phase of the cycle.
(ii)
improved timeliness of field operations,
The phenomenon just discussed MS found to be
(iii)
reduced energy requirements,
important in relation to trop production, in tillage
and in root penetration. If the hardening process
(iv)
reduced wind and water erosion,
took place during land preparation, the draft
required (averaging 250 kN) on these ferrogenous
69
improved soil-water availability to plants,
and ferralitic soils was too high for drafl animals
found in West-Afiica. For better utilisation of
(vi)
maintained soi1 fertility,
existing animal-drawn farm implements and
optimisation of available animal energy, more
(vii)
reduced capital investment for farm
studies need to be oriented towards determining the
implements.
soi1 specifio resistance to traction at diffefent soi1
moisture level.
The combination of two or more conservation
.
practices muit contribute to the implementation of
After the occurrence of the first usefùl rain, farmers
a sustainable farming system to preserve the
in their major@ do not carry out fiéld operations at
enviromnent. Sustainability is complex concept as
optimal soi1 water content as the window in terms
shown by the many definitions encountered in
of working days is usually too short to allow the
literature. Jodha (1990) cited by the FAO ( 1994)
completion of the task on time (Fall, 1985; Lee et
gave a comprehensive and suffïcient deftition:
a:, ,1993). In relation to other limiting factors,
farmers need to be aware of the different
“the ability of the agricultural system to maintain
techniques used in conservation tillage in order to
a certain well-deflned
output level ofperformance
take full advantage of the available soi1 water
over time, and ifrequired, to enhance that output
content.
without damaging the essential ecological integrity
of the system “.
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----.--
-M>
In the dry and semi-humid West-Africa, dhe onset
protect the soi1 fiom wind erosion and to increase
of the rainy season has been investigated ~by
soi1 organic matter. The techniques are yet to be
Sivakumar (1988) who stipulated that it I
accepted by fanmers who are still using trop
corresponds to:
residues for animal feed or as input for other off-
l
season activities.
“‘the date after May 1”’ when rainjbil acciumulated
over 3 consecutive
days is at least 20 mnl and when
More investigations and research are needed to
no dry spell within the next 30 days exce@s 7
design adequate implements and working
days ‘:
components to carry out this type of tillage with
animal traction. The main constraints are:
Because ofthe hardening process phenomenon
effrciency of crops residues burial, level ofdrafI
discussed earlier (“prise en musse”), most of the
required, and alternatives for animal feed.
tropical soils cari be worked only if the soi1 is wet
enough to allow the working component of the
3.4 Seedbed preparation in dry soi1
implement to penetrate the soi1 surface. $Vhen dry,
the amount of draft required is just too hibh for the
Farmers located in areas with rainfall less than
species of draft animais used by farmers. ~ The
600 mm are subject to drastic year-to-year weather
moisture of status of these soils (ferralitic and
variation as drought is more frequent and severe. It
ferragenous) is such that the plastic phase is non-
is crucial for fiumers to take advantage of aIl the
existent as the soi1 goes frorn solid (11 ton 13% v/v)
soi1 moisture provided by unpredictable min
to liquid (14 to 17% v/v) state (Ducreux, il 984;
events. For this reason, the soi1 water management
Fall, 1992). Seedbed preparation with animal
techniques must go beyond tillage to include
traction is only possible in the friable state of the
landscape improvement (live fentes, windbreaks).
soil.
There is no need to wait for the onset of me raih
season to start field activities. The seedbed
Field’operations monitor-mg and experierjces have
preparation in dry soi1 gives more timeliness in
showed that a 20 cm mouldboard plough (working
terms of weeding performed as early as possible to
at an average depth of 10 cm gave the be$t results
allow adequate trop germination and development
in terms of draft requirements and weed control.
as the rain season is short. Three techniques with
Two techniques are applicable: ploughing and
specific implements are available to farmers:
ridging. TO prevent soi1 erosion, the field must not
be ploughed to the edge, a narrow band of gmssed
1) tillage in dry soi1 conditions,
unploughed land needed to be left to pre@t lose
2 ) scarification with tines and different sizes of
soi1 particles to follow waterways (Fall, 1985).
sweeps, and
From the onset of rains, the number of wbrking
3 ) direct seeding with no-till.
days is the most limiting factor for farmers to
achieve their production objectives in terms of
3.4.1 Ploughing in dry soi1
amount of land to seed on time and ener
requirements. Le Moigne (198 1) found
at on one
Ploughing in light soi1 is hard to perform. The
f
hand, ploughing and ridging were not ad isable for
difficulties reside in the lack of stability of the
rainfall between 30 mm/day and 50 mm/day. On
implement as the fimow is tut but not overturned.
the other hand, the operation was diEcul/ to
This technique of ploughing leaves an
perform after a lO-day dry spell. Ifperformed
heterogenous soi1 surface (Ducreux, 1984) to be
correctly, these seedbed preparation techniques
subjected to wind and first rain event erosion. The
gave the best results with regard to yield,~ plant
practice is not sustainable over time and should not
roots development and soi1 protection.
be advocated to fat-mers. In heavier soil, it is not
l
only the quality of the tillage which is a problem
3.3 Post-trop development cycle tillage in wet
but the draft requirements are just too high.
soi1
Implements are subject to damages and to rapid
wear. Field tests have reported the wear of 1 share
This technique has shown its merits in many
per day in ferragenous soils.
experiences conducted on-station, The target
farmers are the same as the above, in areas with
3.5 Scarification of soi1 surface
annual rainfall greater than 800’mm. Thd best
results were obtained in rice growing areas where
The seedbed preparation with implements
soils stayed wet longer than in upland areas after
(generally toolbars) equipped with a set of sweeps
the rains had stopped. The main objectives of this
(3 or 5) of different shapes (full, half and sizes (200
end-of-season-tillage was to take ml1 advantage of
mm to 350 mm). The technique consists of
the level of current status of soi1 moisture and to
allowing the sweeps to till the soi1 subsurface and
but-y the trop residues, after harvest, in order to
to undercut any standing stubble and weeds. The
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The dynamic characteristic of sustainability, as
benefïcial effects of soi1 ornanic matter towards
time is involved, required farmers to adapt the&
protection of soi1 fiom degradation including:
practices according to the changing environme@
(meteorological, economical, etc.). In these
-
supply of CEG to weathered soils,
conditions the use of animal traction has a
-
contribution to soi1 aggregation,
significant role to play towards helping farmerg
-
reduction of the soi1 susceptibility to erosion
achieve more durable reproductive farming
-
decrease of the concentration of Aluminium
systems. Seedbed preparation represents the mpst
and Manganese
critical field operation for which to find adequ@e
<_
increase in flora and fauna activities by
solutions in relation to better soil-water
creating channels for better soi1 aeration.
management, soi1 protection and energy saving$.
The question that remains now has to do with what
The energy savings aspects are viewed by many
is the current status on the techniques available to
policy makers as a reai dilemma as many
~’
farmers or tested by research, especially for
experiences around the world have showed the
seedbed preparation and cultivation, to optimise
positive correlation between energy input and CI
these benefits.
yields per ha. It must be emphasised at this poix
that the energy involved in this study is more
3.2 Seedbed preparation in wet soi1 at the
mechanical than commercial.
beginning of the rainy season
3.1 Energy savings and soi1 pfotection
These seedbed preparation techniques concem
mainly farming systems located in areas with
Conservation tillage aims to maintain and enhan
ratiall more than 800 mm. The advanced soi1
soi1 productivity by preventing land degradation
degradation observed today in many farming
The reduction of the number of field operations
systems in the Humid Tropical West-Afi-ican
achieved with animal traction in comparison if
region is mainly due to ploughing in relation to the
compared with conventional tillage. The level CI
precipitation profile during the rainy season and to
investment on farm implements is lower with
soi1 erosion. Deep ploughing in these conditions
minimum tillage compared to conventional.
cari result in disastrous effects on soi1 resources as
the energy from tropical raindrops Will literally
An important and undesirable side effect of tillai
explode soi1 aggregates and destroy their structure.
is soi1 compaction as energy fiom farm equipme:
E:xperiences conducted in sandy clay soils showed
traffic is directly transmitted to the soil. Ducreu:
that, if the soi1 surface is not protected enough, sol1
(1984) and Fall (1992) tried to evaluate the effet
erosiop (in t/ha) and nutrient loss (i? kg/ha)
of this energy by using the Proctor method whicl
increased respectively by 27 and 15 fimes as runoff
compared the variation of soi1 bulk density at
(in % of rainfall) increased by more than ï 000
different soi1 water contents under simulated
times (Khatibu et al., 1984).
charges: The results were as follow:
For thecrop development aspects, Nicou et al.
Animal traction
65 J/dm3 of soi1
(1970) had showed that on average, roots
development in ferragenous type of soi1 (Beige
Small to medium tractors 104 J/dm3 of soi1
soil) was far better under tillage executed with a
mouldboard plough than under soi1 surface
Heavy machinery
350 J/dn? of soi1
scarification.
.
These levels show that the use of animal traction
The responses given by animal traction users to
cari improve soi1 aeration and water infiltration a:
these environmental conditions were mainly
levels of compaction are less. For the tropical
oriented towards better choice of implements and
soils, especially for ferralitic and ferragenous, the
types of soi1 protection practices to be applied as
water retention is higher in non-compacted soil,
animals got more and more integrated in the
with an exception of silty soils. The beneficial
crapping system. Nevertheless, farmers are
effects provided by animal traction cari be further
generally confronted with three major problems:
improved by adding organiC matter to the soil, SU
as manure and trop residues. These help increase
: > the unpredictable onset of the rainy season,
water holding capacity. Experiences conducted ir
2 ) the narrow range of soi1 rnoisture for seedbed
Ghana showed that the decrease of organic matter
preparation and
in sandy soils fiom 5 to 3% reduced soi1 water
3 ) the rapid growth of v=rd after the onset of
retention fiom 57% to 37%(Beets, 1990). In the
rains
same study, Beets (1990) mentioned the other
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main advantage of this practice resides in the fact
oriented towards meeting their production
that trop residues are left mixed in the soi1 surface
objectives rather than protecting the soi1 f+om
for effective protection against erosion and water
hazards.
runoff. .This is the most widely used technique ~
today in the dry semi-arid Sahel, tiom Senegal to
Gne main reason is the fact that none of the seeders
Tchad). The purpose of this scarification is to
used at present time by farmers is really designed
allow the fust rains to infiltrate and water to be
to plant crops in sod or stubble, meaning that more
stored in the sub-surface horizon for better seed
investigations are needed to irnprove farmers’-
germination. The draft requirements are moderate.
practices.
as the depth range of cultivation is around 6 to 9
cm. It must be noted that the positive effects of
Globally, the advantages of this technique are Fe
this technique on yield have not been
following aspects:
demonstrated.
-
reduction of production costs,
3.6 Shallow sub-soiling
-
improvement of soi1 retention and less runoff;
-
decrease in level of soi1 compaction,
Special60’ angle-chisels, named’Gouvy have been
-
better timeliness in seeding,
tested lately on farmers’ fields of the Groundnut
-
reduction in some weather related risks.
Basin of Senegal aiming to improve soi1 water
status in dry soi1 after the fust rains (Pirot and
~
4.
Implements selection discussion and
Paris, 1980; Garin and Sene, 1988). Le Thiec and
recommendations
Bordet (1988) had also tested a similar steel-made
chisel built by CEEMATKXRAD and called RS in
The same types of implements are encountered in
Botswana and in Burkina Faso. It consisted of a
a11 the West-Afiican countries except for Guinea
.sihgle rigid standard frame toolbar equipped with
where a significant part of the implements were
an adjustable 60’ angle-chisel. At an average depth
introduced from China in 1968 at the earlier stage
of 8- 10 cm, the chisel shatters and loosens the soi1
of animal traction implementation. Even ifthe
especially in dry conditions. It requires less draft
implements are more less the same across the
compared to mouldboard plough and also bas the
countries, most of them have been adapted to fit the
advantage of leaving trop residues on the surface.
local situation, with regard to draft animais, soi1
The chisel is ineffective when the soi1 is already
types, farmers height etc. The Ciwara and Houe
wet, depending on the importance of water stress
Asine (Mali) were adapted hem the Sine 9
and the types of crops (groundnut, millet, maize).
cultivator and the Occidental Hoe respectively.
The distance between two single subsoil rows cari
The main local manufacturers are SISMAR and
vary from 30 to 100 cm. Water f?om rain Will ented
URPATA in Guinea.
rapidly in the shattered rows to improve water
lateral redistribution in the soi1 profile.
Implements are still imported l?om developed
countries (EMCOT, BAJAC. EBRA, etc.) and parts
In general on one hand, the chisels had improved
of tbe implements used today are built by local
the soi1 surface rugosity by 20 to 60% to tut down
blacksmiths.
:significantly the water runoff during the frrst rains
of the season. Groundnut yield was increased by
The most used implement types are moulboard
120% the first year. From the present status of
ploughs, ridger ploughs, spring and rigid tine
research on animal traction towards water control,
cultivators, harrows, seeders and groundnut
the seedbed preparation in dry soils needs further
diggers. These implements have not changed since
:,tudies and investigations towards the development
the 1960s except for some minor adaptations. In
of better tools to enhançe the soi1 moisture regime.
the selection and utilisation process, farmers are
generaHy confronted with the challenge of fitting
35.7 Direct seeding in dry soi1
the energy requirements for different tïeld activities
to the draft animal without degrading the
This is widely used in the Senegalese groundnut
environment. Each implement has its own
basin in the Gambia. The technique consists of
utilization requirements in tenus of when and how
using a one-row-weeder (Super Eco seeder fiom
to use it.
SISMAR) pulled by a donkey or a horse. It
produces minimum of soi1 disturbance (Metcalfe
TO slow down the process of soi1 degradation
and Elkins, 1980). Alter the seed is placed in dry
currently observed in farmers conditions, it is
s4, farmers pray for the rain to be at the rendez-
crucial that animal drawn implements be operated
VIXU. In this situation, timeliness is not a problem.
by skilled operators. Training Car-mers to new
However, it is important to mention that the way
techniques is one way to limit the unwanted effects
this practice is carried out by farmers is more
of tbe technology on the direct environment. It is
14s
Conservation tillage with Animal Traction: ATNESA Resource Book
also important to keep in mind that th& learning
-
1s it possible to explain to farmers what
process of farmers cari be very slow +d cari take
environmental sustainability is about?
years (Fall, 1997).
-
HO~ cari farmers manage the knowledge
l
generated SO far under the cenceptual
The best practice to&ards enviromne&al
fizmework of sustainability as interpreted by
sustainability with animal traction sta$s first of a11
WCED (1987).
with increasing tbe range of implement selection
w=ith new types to take into account thk changing
Because the level of animal traction utilization is
environmental conditions. Mechanisjd farming
still low in most parts of West Afiica, the room lefi
must be conducted fiom a holistic perspective
for improvement cari caver different aspects:
within agroforestry-based farming sy$ems in order
(0
des@ of better implements ta include
to improve land use. Beets (1989) defmeci
post-tillage operations like weeding and
agroforestry as a land-use in which tries are grown
hart-esting,
in such spatial arrangement to foster qoth
(ii)
optimization of draft animal utilisation to
ecological and economic interactions between the
take full advantage pf the available
tree and the other component of the fving
energy by planning field operations
system: soi1 conservation by the rootihg systems,
during the most suitable hours of the day,
dune fixation, fertility improvement, &dder trees
(iii)
meeting the feeding requirements of the
for animais, windbreaks, etc.
I
working animais tiom better integration
of different fting system components,
5. Conclusion
(ii)
emphasising farmers’ training sessions as
part of any animal-traction-based projects
The sustainability of the environment 1s a major
to reduce the learning period.
concem to policy makers and to farm@s willing to
adopt new practices without jeopardisbg
References
agricultural productivity. The introduçtion of
animal traction in smallholders farminlg systems in
Beet, W C. 1990. Raising and Sustaining Productivity of
West Afiica has brought about signifilant positive
Smallholder Farming Systems in the Tropics. Agbé
Publishing, Akmaar Holland.
changes in the production systems buti on the other
hand, has induced advanced soi1 degrddarion
Charreau, C et Nicou, R. 1971. L’amélioration du profil
processes. It is possible to reverse the1 situation by
culturel dans les sols sableux et sablo-agrileux de la
introducing new farming practices thai go beyond
sone Tropicale sèche Ouest-Africaine et ses incidences
agronomiques (d’après les travaux de recherches des
simple animal traction utilisation.
~
chercheurs de I’IRAT en Afrique de l’Ouest).
Agronomie Tropicale 26903-978.
At this stage of development, animal thaction has
proven its positive impact in raising cqopping
Ducreux, A. 1984. Caractérisation mécanique d&ols sableux
et sablo-agrileux de la z.one Tropicale séche de
systems productivity.
However, the téchnology
l’Afrique de l’ouest. Etude d’un prototype d’outils
needs to be adjusted to the rapid chan$es taking
permettant de les travailler en période sèche. Thése de
place in the environment. Efforts musq be oriented
Docteur Ingènieur en Sciences Agronomiques-Option:
towards designing tools and introducqg new
Pédologie. AcadBmie de Montpellier, Universitè des
Scienw et Techniques du Languedoc. Montpellier,
practices to take full advantage of the tcarce
France.
amqunt of rains falling in different p+ of West
Africa today. This Will help mitigate lhe effects of
Dupont, Ci. 1986. Measurement and Analysis of Aaoclimatic
droughts on trop production. The techpiques will
Zones for West Afkica.
vary from one agro-ecosystem to another mainly
Fall, A. 1985. Situation actuelle de l’environnement et de
characterised by the level of wetness. ;To lhis
l’utilisation du pard ce matérials de culture attelée en
perspective, agroforestry practices ne&l to be
Basse Casaamance. Mémoire de titularisation.
investigated to complement any activip around the
DRSPTT en milieu rural. ISRA.
use of animal traction.
l
Fall, A 1992. Relations outils-sols: Comportements et
caractéristiquess mécaniques de sols sablo-argileux et
Emphasis Will be placed 0; a good ex ~nte farmers’
argileux. LAGEPGY, ENSA. Montpellier, France.
understanding of the potential contrib d”tiorn of the
Fall, A 1997. Methodology for evaluating the impact of ammal
new techniques towards solving the sytainability
traction at the fann level in a small scale multicropping
and soi1 protection constraints. For Ise reasons,
system (Basse Casamance, senegal). Suhmitted to
animal traction projects in the future +st be
MSU in partial fulfullment of the requirements for the
apprehended fiom a multidisciplinary
degree of Doctor of pHilosophy. Ag Engineering, E
Lansing, USA.
A number of questions need to be ad
implementing fùture animal traction
FAO. 1994. Farming systems development and soi1
conservation. Rome, Italy
146
Conserv#ion tillage with A n i m a l T r a c t i o n :
ATNESA Resource Book
Jaeger, KW. 1984. Agricuhural Mechanization: The
)
zone sah&anne. Etude metbodologique. CEEMAT,
economics of animal traction in Burkina Faso.
Paris, France.
of Philosophy Dimertation submitted to IFPRI S”fI:d
University.
Metcalfe, D S snd Elkins, D M. 1980. Crop production:
Principles and practices.. 4u Edition. MacMiian
Jodha, N S. 1990. Sustainable Agriculture in Fra8ile Res@te
Pubhshing Co. New York, USA.
Zones: TechnologicaJ Imperatives. Paper prese ‘ted at
the International Symposium on Natural resour 4
Nicou, R et ut. 1970. Comparaison de l’enracinement de quatre
s9EE Sustainable Agriculture, New Delhi,
varictts de riz pluvial en preserxe ou absence de
travail du sol. L’ Agronomie tropicale 8:639-659.
Khatiby A 1 et cl. 1984. Effects of tillage methods snd ~
Posner, J L et ut! 1988. Les sutémes de production en Basse
mulching on erosion and physical properties of a sandy
Casamance et les strat6gies paysannes face au déficit
clay loam in an equatorial warm hurnid region. Fteid
phtviom&rique. ISRAMSA International
Crops Research 8:239-254.
Development Papers.
Lee, J V D et a% 1993. Design and validation of an animaj
Sivakumur, M V K. 1988. Predicting rainy season potentiai
traction module for a smahholder livestock sy&&
from the omet of rains in the Sahelian and Sudanian
simulation model. Agricuhural Systems 43:199-227.
climatic zones of West-Africa. Agricuhural and Forest
Meteorology 42:295-305.
Le Mo@re, M. 1981. Contraintes pos&s par
mécanisation dans les unit& de production
Conservation tillage
th Animal Traction: ATNESA Resource Book
the West-African region
br
Alioune Fall’, and Adama Faye2
IAgricultural
Mechanisation, ISRAKRA Djibélor, 2Animal Scient& Coopération Suis$
I
,
Abstract
I
The paper reviews the utilization levels of animal traction for better soi1 and water management, through
conservation tillage in the West Aj?ica region. Various tools and techniques used by farmers are reported.
Recommendations
in order to improve .farmers’ environmental conditions for better agricultural productivity
and sustainability have been pro@sed. -
translate the farmers’ concern to reach sustainable
1. Introduction
cropping systems through decisions to be made on
when and how to conduct field activities in relation
Farmers in the West-Afiican region are mainly
to available resources (Jouve, 1986). However,
smallholders who must contend with increasing
there is a number of limiting factors on farmers’
population pressure on available land, low level of
performance which cari help explain their response
mechanisation, short fallow, permanent cropping
to the situation.
and risky rainy, seasons. The existing farming
systems seem to be vulnerable with regard to
A number of research studies, conducted both on-
continuous degradation of the farmers’
station and on-farm throughout the region, have
environmental conditions. Current practices have
shown that sustainability of cropping systems is
led to advanced soi1 erosion which has
better achieved when agricultural practices are
compromised productivity on both land and crops.
aimed ,at improving plant-soil-water relations.
Farmers depend greatly on animal traction for
1.1 Objective
energy supply to meet their agricultural production
objectivés. The energy provided represents more
The objectives of this paper are:
than 90% of the mechanical energy used in
agriculture in the area of study. The use of animal
(9
to review the use of animal traction in the
traction is viewed by Jaeger (1984) as an important
region towards better soil-water
step in creating more production opportunities and
management through conservation tillage,
increasing retums through better land preparation
and jmproved timeliness of field operations.
(ii)
to identify the most suitable tools and
However, the intensity of animal traction utilisation
techniques available to farmers and
in relation to the level of farmers’ experience is
highly variable fiom country to country.
(iii)
to formulate recommendations in order to
improve farm environmental conditions
Animal traction was introduced in Senegal, Guinea
for enhanced sustainability.
and Mali in the late 1920s and early 1930s. The
most significant impact of animal traction in
TO do SO, major research fïndings in relation to
today’s farming systems h?s been the increase in
major constraints to soil-water management, tillage
cultivated area per active household member rising
and trop growth are discussed. Most of the
fi-om 30 to 40% in Senegal and 40 to 70% in Mali.
researches on animal traction have been conducted
in Senegal, Mali, Guinea, Togo, Sierra Leone,
For the last two decades, agriculhual production
Burkina Faso, Niger, Nigeria and Tchad. However,
throughout the Sahel has been mainly bound by the
there is emphasis on research activities conduced in
shortage of rainfall along with its uneven
Senegal.
distribution during the rainy season. The amount
of rainfall has decreased by an average of 33 to
45%, inducing new farmers’ production strategies
towards meeting food security requirements
(Posner et al., 1988). The coping sbategies
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.. .
2. Climate and soils description
toposequence and the types to the texture of the
surface horizon. Sub-Saharan Aiïica was divided
2.1 Climates
into five large zones (Charreau, 1974):
The climatic transition in West Afi-ica takes place
-
In the northern part of Senegal, Mali and Niger
across a short distance between humid and dry
and Tchad: sand and dunes.
weather. In this short distance away from the
equator, the occurrence of two rainy seasons is
-
In the Niger Rive?s arc and in a great part of
observed. The dry spell between the two rain
the Tchad basin: alluvial deposits ranging Çom
seasons is short and cari vary in length in relation to
pure sand to fine clay.
the duration of the sun cycles. Vegetation in tbe
area corresponds to the humid forest. The high
-
West, South-West, and East’of the Niger
amount of rainfall has the tendency to create more
River’s arc in Burkina Faso, in two-thirds of
soi1 nutrients and leaching problems leading to
Senegal, and in Southem Tchad were found
fiagile and infertile soils. Soi1 protection is a must.
the Terminal Continental formations. The
materials generally went through a strong
As pointed out by Beets (1990), the weather around
ferralitic alteration.
the 15’ latitude is divided into two distinct seasons
in relation to occurrence of rains: dry season and
-
In the Southern part of Niger River3 arc, in
rainy season. The area where this climate prevails
the central part of Mali, and in the Western
is becoming narrower with the global pejoration of
part of Burkina Faso is a vast area of Combro-
the weather. Therainfall is still significant and
Ordovician sandstones overlanded by an
relati,vely reliable. It stretches from moist to forest
ancient “lateritic” iron pan.
Savannah with an average annual rainfall of
1000 mm. Water runoff is a serious problem as are
-
In the southem part of Mali, in Burkina Faso,
forest tires during the dry season. Fires are
in the central part of Tchad: crystalline shield
fiequent and cari burn completely the grass
made up of plutonic rocks, metamorphic rocks
covering and protecting the soil, leaving bare soi1
and volcanic rock”
surfaces to receive the first tropical rain events at
the beginning of the rainy season.
The soi1 map showed that large areas of the West-
Afiican region are occupied by grey and yellow-to-
Northward, the semi-arid to arid types of climate
beige ferragenous soils (Alfïsol), and by red
prevail in the central and northern part of Sahel
ferralitic soils (Oxisol). These soils are mainly
countries Çom Senegal to Tchad. The weather is
characterised by a field capacity of 15 to 20% v/v
dry and hot with one short rainy season. Rainfall is
and a wiltiuk point of 7 to 9% v/v. The oxic
unreliable as drought situations are always reported
horizon of the ferragenous and ferralitic soils are
from year to year in terms of mid-season droughts
mainly made of a mixture of three elements:
or dry spells during the rainy season. Many studies
kaolin, amorphous hydrated oxides (iron and
have showed difficulties encountered in finding
aluminium), and quartz. They are desaturated and
solution to the drought situations.
characterised by a low cation exchange capacities
(CEC) due to the presence of kaolinite, and by
Dupont (1986) and Sivakumur (1988) developed
having almost reached the end of weathering in
techniqu’es to predict the level of probability of dry
their evolution.
spells from the onset of rains to the end of the final
development stage of the cropr, grown at the farm.
The ferragenous soils (“sol beige”) present a sandy
to course loamy texture in the Upper horizon with a
2.2 Soils of West Africa
sub-angular blocky structure and a fine loam to fine
clayey texture in the deeper horizon with angular
The soils in the West-Afiican region have been
blocky structure. The ferralitic soils (“sol rouge”
surveyed for more than twenty years by teams of
or red soils) present some altïc characteristics with
Alïican and European soi1 scientists. Charreau
sub-surface horizons made of clay accumulation.
(1974) published the first m&t exhaustive soi1
Their texture and structure are similar to the grey
classification for the Sub-Saharan Ahica. This was
type. Other important types of soils are those
made possible by a team of IRAT and ORSTOM
located in dryer areas, mainly made of sandy
(France) soi1 scientists. The West-African soi1 map
texture and these soils represent a transition
was made of 12 classes subdivided into sub-
between ferragenous and vertisol types (Ducreux,
classes, groups and sub-groups, families, series and
1984).
types of soil. The family was composed of soils
originating f?om the same kind of parent material.
The characteristics of these soils are important for
The series related to the position of the soi1 on the
two main reasons:
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Conservation tillage w i t h A n i m a l T r a c t i o n :
ATNESA Resource Book
The key success to environmental and farming
-
the wetting and drying cycles in relation to the
system sustainability is to train smallholders to
aggregates and structure stability, and
become soi1 moisture managers by giving them
more insight on subjects like:
-
the hardening process (“prise en masse”)
taking place during the dry season and after
0
Animal-drawn implements selection with
intermittent rainfalls followed by dry spells
suitable working components.
during the rainy season.
?
Physical and mechanical characteristics of
For these reasons, the management of soi1 moisture
their soi1 types.
regime appears to be a critical issue for plant
growth in this part of Africa, especially at the
?
Soi1 moisture regime (infiltration, holdmg
beginning of the rainy season.
capacity).
Nicou (1975) bd studied these &VO combined
o
Consumption rate and vegetative development
characteristics which tend to confer to thesoils
of grown crops.
specific physical and mechanical behaviour. A
major fïnding, confirmed by Ducreux (1984) was
3.
Conservation tillage with animal traction
the fact that the low clay content in the Upper
horizon (8 to 12%) and the presence of kaolinite
Research activities on no-till, minimum tillage, and
are responsible for the tendency of the aggregates
later on conservation tillage with animal traction
to harden tbrough cementation during the drying
started in the early 1960s in many West tican
phase of the cycle.
countries. These activities were mainly conducted
on station until1979 when the shortage of rainfall
A texh&l index called ‘Hardening Index”, defined
and the drought situation induced significant
as the ratio of the clay content over the coarse
changes in farmers’ production systems. However,
fraction of the,soil (coarse silt + coarse Sand), was
conservation tillage could not be isolated fiom the
introduced to describe the physical be,haviour of the
broader practices of soi1 conservation. The
tropical soils. They found Chat there was a linear
baseline was to develop techniques that:
relationship between the hardening of the soi1
upper horizons and the HI index for soils studied in
(9
reduced the number of mechanised field
Senegal and Niger. The higher the HI index, the
operations,
higher the tendency of the soils to harden during
the drying phase of the cycle.
(ii)
improved timeliness of field operations,
The phenomenon just discussed MS found to be
(iii)
reduced energy requirements,
important in relation to trop production, in tillage
and in root penetration. If the hardening process
(iv)
reduced wind and water erosion,
took place during land preparation, the draft
required (averaging 250 kN) on these ferrogenous
69
improved soil-water availability to plants,
and ferralitic soils was too high for drafl animals
found in West-Afiica. For better utilisation of
(vi)
maintained soi1 fertility,
existing animal-drawn farm implements and
optimisation of available animal energy, more
(vii)
reduced capital investment for farm
studies need to be oriented towards determining the
implements.
soi1 specifio resistance to traction at diffefent soi1
moisture level.
The combination of two or more conservation
.
practices muit contribute to the implementation of
After the occurrence of the first usefùl rain, farmers
a sustainable farming system to preserve the
in their major@ do not carry out fiéld operations at
enviromnent. Sustainability is complex concept as
optimal soi1 water content as the window in terms
shown by the many definitions encountered in
of working days is usually too short to allow the
literature. Jodha (1990) cited by the FAO ( 1994)
completion of the task on time (Fall, 1985; Lee et
gave a comprehensive and suffïcient deftition:
a:, ,1993). In relation to other limiting factors,
farmers need to be aware of the different
“the ability of the agricultural system to maintain
techniques used in conservation tillage in order to
a certain well-deflned
output level ofperformance
take full advantage of the available soi1 water
over time, and ifrequired, to enhance that output
content.
without damaging the essential ecological integrity
of the system “.
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----.--
-M>
In the dry and semi-humid West-Africa, dhe onset
protect the soi1 fiom wind erosion and to increase
of the rainy season has been investigated ~by
soi1 organic matter. The techniques are yet to be
Sivakumar (1988) who stipulated that it I
accepted by fanmers who are still using trop
corresponds to:
residues for animal feed or as input for other off-
l
season activities.
“‘the date after May 1”’ when rainjbil acciumulated
over 3 consecutive
days is at least 20 mnl and when
More investigations and research are needed to
no dry spell within the next 30 days exce@s 7
design adequate implements and working
days ‘:
components to carry out this type of tillage with
animal traction. The main constraints are:
Because ofthe hardening process phenomenon
effrciency of crops residues burial, level ofdrafI
discussed earlier (“prise en musse”), most of the
required, and alternatives for animal feed.
tropical soils cari be worked only if the soi1 is wet
enough to allow the working component of the
3.4 Seedbed preparation in dry soi1
implement to penetrate the soi1 surface. $Vhen dry,
the amount of draft required is just too hibh for the
Farmers located in areas with rainfall less than
species of draft animais used by farmers. ~ The
600 mm are subject to drastic year-to-year weather
moisture of status of these soils (ferralitic and
variation as drought is more frequent and severe. It
ferragenous) is such that the plastic phase is non-
is crucial for fiumers to take advantage of aIl the
existent as the soi1 goes frorn solid (11 ton 13% v/v)
soi1 moisture provided by unpredictable min
to liquid (14 to 17% v/v) state (Ducreux, il 984;
events. For this reason, the soi1 water management
Fall, 1992). Seedbed preparation with animal
techniques must go beyond tillage to include
traction is only possible in the friable state of the
landscape improvement (live fentes, windbreaks).
soil.
There is no need to wait for the onset of me raih
season to start field activities. The seedbed
Field’operations monitor-mg and experierjces have
preparation in dry soi1 gives more timeliness in
showed that a 20 cm mouldboard plough (working
terms of weeding performed as early as possible to
at an average depth of 10 cm gave the be$t results
allow adequate trop germination and development
in terms of draft requirements and weed control.
as the rain season is short. Three techniques with
Two techniques are applicable: ploughing and
specific implements are available to farmers:
ridging. TO prevent soi1 erosion, the field must not
be ploughed to the edge, a narrow band of gmssed
1) tillage in dry soi1 conditions,
unploughed land needed to be left to pre@t lose
2 ) scarification with tines and different sizes of
soi1 particles to follow waterways (Fall, 1985).
sweeps, and
From the onset of rains, the number of wbrking
3 ) direct seeding with no-till.
days is the most limiting factor for farmers to
achieve their production objectives in terms of
3.4.1 Ploughing in dry soi1
amount of land to seed on time and ener
requirements. Le Moigne (198 1) found
at on one
Ploughing in light soi1 is hard to perform. The
f
hand, ploughing and ridging were not ad isable for
difficulties reside in the lack of stability of the
rainfall between 30 mm/day and 50 mm/day. On
implement as the fimow is tut but not overturned.
the other hand, the operation was diEcul/ to
This technique of ploughing leaves an
perform after a lO-day dry spell. Ifperformed
heterogenous soi1 surface (Ducreux, 1984) to be
correctly, these seedbed preparation techniques
subjected to wind and first rain event erosion. The
gave the best results with regard to yield,~ plant
practice is not sustainable over time and should not
roots development and soi1 protection.
be advocated to fat-mers. In heavier soil, it is not
l
only the quality of the tillage which is a problem
3.3 Post-trop development cycle tillage in wet
but the draft requirements are just too high.
soi1
Implements are subject to damages and to rapid
wear. Field tests have reported the wear of 1 share
This technique has shown its merits in many
per day in ferragenous soils.
experiences conducted on-station, The target
farmers are the same as the above, in areas with
3.5 Scarification of soi1 surface
annual rainfall greater than 800’mm. Thd best
results were obtained in rice growing areas where
The seedbed preparation with implements
soils stayed wet longer than in upland areas after
(generally toolbars) equipped with a set of sweeps
the rains had stopped. The main objectives of this
(3 or 5) of different shapes (full, half and sizes (200
end-of-season-tillage was to take ml1 advantage of
mm to 350 mm). The technique consists of
the level of current status of soi1 moisture and to
allowing the sweeps to till the soi1 subsurface and
but-y the trop residues, after harvest, in order to
to undercut any standing stubble and weeds. The
144
Conservati& Mage tith Animai Traction: ATNESA Resource Book
The dynamic characteristic of sustainability, as
benefïcial effects of soi1 ornanic matter towards
time is involved, required farmers to adapt the&
protection of soi1 fiom degradation including:
practices according to the changing environme@
(meteorological, economical, etc.). In these
-
supply of CEG to weathered soils,
conditions the use of animal traction has a
-
contribution to soi1 aggregation,
significant role to play towards helping farmerg
-
reduction of the soi1 susceptibility to erosion
achieve more durable reproductive farming
-
decrease of the concentration of Aluminium
systems. Seedbed preparation represents the mpst
and Manganese
critical field operation for which to find adequ@e
<_
increase in flora and fauna activities by
solutions in relation to better soil-water
creating channels for better soi1 aeration.
management, soi1 protection and energy saving$.
The question that remains now has to do with what
The energy savings aspects are viewed by many
is the current status on the techniques available to
policy makers as a reai dilemma as many
~’
farmers or tested by research, especially for
experiences around the world have showed the
seedbed preparation and cultivation, to optimise
positive correlation between energy input and CI
these benefits.
yields per ha. It must be emphasised at this poix
that the energy involved in this study is more
3.2 Seedbed preparation in wet soi1 at the
mechanical than commercial.
beginning of the rainy season
3.1 Energy savings and soi1 pfotection
These seedbed preparation techniques concem
mainly farming systems located in areas with
Conservation tillage aims to maintain and enhan
ratiall more than 800 mm. The advanced soi1
soi1 productivity by preventing land degradation
degradation observed today in many farming
The reduction of the number of field operations
systems in the Humid Tropical West-Afi-ican
achieved with animal traction in comparison if
region is mainly due to ploughing in relation to the
compared with conventional tillage. The level CI
precipitation profile during the rainy season and to
investment on farm implements is lower with
soi1 erosion. Deep ploughing in these conditions
minimum tillage compared to conventional.
cari result in disastrous effects on soi1 resources as
the energy from tropical raindrops Will literally
An important and undesirable side effect of tillai
explode soi1 aggregates and destroy their structure.
is soi1 compaction as energy fiom farm equipme:
E:xperiences conducted in sandy clay soils showed
traffic is directly transmitted to the soil. Ducreu:
that, if the soi1 surface is not protected enough, sol1
(1984) and Fall (1992) tried to evaluate the effet
erosiop (in t/ha) and nutrient loss (i? kg/ha)
of this energy by using the Proctor method whicl
increased respectively by 27 and 15 fimes as runoff
compared the variation of soi1 bulk density at
(in % of rainfall) increased by more than ï 000
different soi1 water contents under simulated
times (Khatibu et al., 1984).
charges: The results were as follow:
For thecrop development aspects, Nicou et al.
Animal traction
65 J/dm3 of soi1
(1970) had showed that on average, roots
development in ferragenous type of soi1 (Beige
Small to medium tractors 104 J/dm3 of soi1
soil) was far better under tillage executed with a
mouldboard plough than under soi1 surface
Heavy machinery
350 J/dn? of soi1
scarification.
.
These levels show that the use of animal traction
The responses given by animal traction users to
cari improve soi1 aeration and water infiltration a:
these environmental conditions were mainly
levels of compaction are less. For the tropical
oriented towards better choice of implements and
soils, especially for ferralitic and ferragenous, the
types of soi1 protection practices to be applied as
water retention is higher in non-compacted soil,
animals got more and more integrated in the
with an exception of silty soils. The beneficial
crapping system. Nevertheless, farmers are
effects provided by animal traction cari be further
generally confronted with three major problems:
improved by adding organiC matter to the soil, SU
as manure and trop residues. These help increase
: > the unpredictable onset of the rainy season,
water holding capacity. Experiences conducted ir
2 ) the narrow range of soi1 rnoisture for seedbed
Ghana showed that the decrease of organic matter
preparation and
in sandy soils fiom 5 to 3% reduced soi1 water
3 ) the rapid growth of v=rd after the onset of
retention fiom 57% to 37%(Beets, 1990). In the
rains
same study, Beets (1990) mentioned the other
143
Conservation Mage u
I A n i m a l T r a c t i o n :
ATNEBA Resource Book
main advantage of this practice resides in the fact
oriented towards meeting their production
that trop residues are left mixed in the soi1 surface
objectives rather than protecting the soi1 f+om
for effective protection against erosion and water
hazards.
runoff. .This is the most widely used technique ~
today in the dry semi-arid Sahel, tiom Senegal to
Gne main reason is the fact that none of the seeders
Tchad). The purpose of this scarification is to
used at present time by farmers is really designed
allow the fust rains to infiltrate and water to be
to plant crops in sod or stubble, meaning that more
stored in the sub-surface horizon for better seed
investigations are needed to irnprove farmers’-
germination. The draft requirements are moderate.
practices.
as the depth range of cultivation is around 6 to 9
cm. It must be noted that the positive effects of
Globally, the advantages of this technique are Fe
this technique on yield have not been
following aspects:
demonstrated.
-
reduction of production costs,
3.6 Shallow sub-soiling
-
improvement of soi1 retention and less runoff;
-
decrease in level of soi1 compaction,
Special60’ angle-chisels, named’Gouvy have been
-
better timeliness in seeding,
tested lately on farmers’ fields of the Groundnut
-
reduction in some weather related risks.
Basin of Senegal aiming to improve soi1 water
status in dry soi1 after the fust rains (Pirot and
~
4.
Implements selection discussion and
Paris, 1980; Garin and Sene, 1988). Le Thiec and
recommendations
Bordet (1988) had also tested a similar steel-made
chisel built by CEEMATKXRAD and called RS in
The same types of implements are encountered in
Botswana and in Burkina Faso. It consisted of a
a11 the West-Afiican countries except for Guinea
.sihgle rigid standard frame toolbar equipped with
where a significant part of the implements were
an adjustable 60’ angle-chisel. At an average depth
introduced from China in 1968 at the earlier stage
of 8- 10 cm, the chisel shatters and loosens the soi1
of animal traction implementation. Even ifthe
especially in dry conditions. It requires less draft
implements are more less the same across the
compared to mouldboard plough and also bas the
countries, most of them have been adapted to fit the
advantage of leaving trop residues on the surface.
local situation, with regard to draft animais, soi1
The chisel is ineffective when the soi1 is already
types, farmers height etc. The Ciwara and Houe
wet, depending on the importance of water stress
Asine (Mali) were adapted hem the Sine 9
and the types of crops (groundnut, millet, maize).
cultivator and the Occidental Hoe respectively.
The distance between two single subsoil rows cari
The main local manufacturers are SISMAR and
vary from 30 to 100 cm. Water f?om rain Will ented
URPATA in Guinea.
rapidly in the shattered rows to improve water
lateral redistribution in the soi1 profile.
Implements are still imported l?om developed
countries (EMCOT, BAJAC. EBRA, etc.) and parts
In general on one hand, the chisels had improved
of tbe implements used today are built by local
the soi1 surface rugosity by 20 to 60% to tut down
blacksmiths.
:significantly the water runoff during the frrst rains
of the season. Groundnut yield was increased by
The most used implement types are moulboard
120% the first year. From the present status of
ploughs, ridger ploughs, spring and rigid tine
research on animal traction towards water control,
cultivators, harrows, seeders and groundnut
the seedbed preparation in dry soils needs further
diggers. These implements have not changed since
:,tudies and investigations towards the development
the 1960s except for some minor adaptations. In
of better tools to enhançe the soi1 moisture regime.
the selection and utilisation process, farmers are
generaHy confronted with the challenge of fitting
35.7 Direct seeding in dry soi1
the energy requirements for different tïeld activities
to the draft animal without degrading the
This is widely used in the Senegalese groundnut
environment. Each implement has its own
basin in the Gambia. The technique consists of
utilization requirements in tenus of when and how
using a one-row-weeder (Super Eco seeder fiom
to use it.
SISMAR) pulled by a donkey or a horse. It
produces minimum of soi1 disturbance (Metcalfe
TO slow down the process of soi1 degradation
and Elkins, 1980). Alter the seed is placed in dry
currently observed in farmers conditions, it is
s4, farmers pray for the rain to be at the rendez-
crucial that animal drawn implements be operated
VIXU. In this situation, timeliness is not a problem.
by skilled operators. Training Car-mers to new
However, it is important to mention that the way
techniques is one way to limit the unwanted effects
this practice is carried out by farmers is more
of tbe technology on the direct environment. It is
14s
Conservation tillage with Animal Traction: ATNESA Resource Book
also important to keep in mind that th& learning
-
1s it possible to explain to farmers what
process of farmers cari be very slow +d cari take
environmental sustainability is about?
years (Fall, 1997).
-
HO~ cari farmers manage the knowledge
l
generated SO far under the cenceptual
The best practice to&ards enviromne&al
fizmework of sustainability as interpreted by
sustainability with animal traction sta$s first of a11
WCED (1987).
with increasing tbe range of implement selection
w=ith new types to take into account thk changing
Because the level of animal traction utilization is
environmental conditions. Mechanisjd farming
still low in most parts of West Afiica, the room lefi
must be conducted fiom a holistic perspective
for improvement cari caver different aspects:
within agroforestry-based farming sy$ems in order
(0
des@ of better implements ta include
to improve land use. Beets (1989) defmeci
post-tillage operations like weeding and
agroforestry as a land-use in which tries are grown
hart-esting,
in such spatial arrangement to foster qoth
(ii)
optimization of draft animal utilisation to
ecological and economic interactions between the
take full advantage pf the available
tree and the other component of the fving
energy by planning field operations
system: soi1 conservation by the rootihg systems,
during the most suitable hours of the day,
dune fixation, fertility improvement, &dder trees
(iii)
meeting the feeding requirements of the
for animais, windbreaks, etc.
I
working animais tiom better integration
of different fting system components,
5. Conclusion
(ii)
emphasising farmers’ training sessions as
part of any animal-traction-based projects
The sustainability of the environment 1s a major
to reduce the learning period.
concem to policy makers and to farm@s willing to
adopt new practices without jeopardisbg
References
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