|Animal Traction in Rainfed Agriculture in Africa and South America (GTZ, 1991, 311 p.)|
|F. Case studies: West Africa:|
3.1 The country and the population
Senegal has a total surface area of ca. 197,000 km and thus is somewhat smaller than the Federal Republic of Germany (250,000 km). In 1988 there was a population of approximately 7.1 mil inhabitants with a growth rate of 2.9 %. On the average the population density is about 35 inhabitants per km this varies considerably from 6 per kmast Senegal to 2500 per kmhe Cap Vert region. 70 % of the Senegalese people live in rural areas. The rapid rural exodus is creating a population explosion in Dakar, the capital, as well as the Cap Vert region. (Statistisches Bundesamt, 1987; Nohlen, 1989)
The country has relatively few natural resources, phosphate being the most important. The main share of the gross national product is covered by agricultural products, representing 20 - 30 % of the total, whereby great fluctuations occur depending on the climate. Since Senegal is the world's largest exporter of groundnuts, the record harvest in 1987/88 of 950,000 tons severely depressed the world market price. Approximately 1/4 of the turnover of the industry in Senegal is generated by oil mills. About half of the industrial products are exported, mainly groundnut products, tinned fish, phosphate, shoes and textiles. Transportation routes have been built up relatively well for African conditions. (Statistisches Bundesamt, 1987; Nohlen, 1989)
Senegal along with six other West African countries belongs to the Communaut FinanciŠre Africaine, which issues the franc CFA currency unit. It has a fixed exchange rate of 50 CFA to the French franc. Therefore, currency exchange problems do not exist to the extent known in other countries of the Third World. The importation of goods is thus easier within certain limits. In 1987 the expenditures for imports were covered by exports to 58 % (Nohlen, 1989).
3.2 Natural endowment
The south of Senegal has a wet and try tropical climate with a rainy season from June to October. In the north there is a semiarid climate with only a 3-month rainy season and an uncertain amount of rainfall. The precipitation ranges from 1200 mm per annum in the southwest to 300 mm in the north of the country. (Statistisches Bundesamt, 1987) It is being observed that from the northeast to the southwest aridity is on the increase, thus changing the overall agricultural production systems.
Soils and topography
Senegal is predominantly flat; the existing slight rolling hills are seldom higher than 200 m. The soils are mostly sandy (Sols Ferrugineux Tropicaux -FS; Alfisol -USST) to clayey (Sols Ferralitiques -FS; Ultisol - USST). In some regions as in the Casamance rough relief is encountered, in which soil types change drastically within short distances between plateaus, slopes and valleys. On the slopes the soil is often clayey, in part with iron concretions which are difficult to till. In the valleys heavy alluvial soils (Sols Hydromorphes - FS) are found. The soils on plateaus and slopes are characterized by very rapid compaction during the dry season and render soil preparation most difficult (Fall and Ndiame, 1988a). Sandy soils are less fertile and have a weak structure. Surface crusting and compaction become a problem. Macropores can only be created on the basis of biological activity.
The coastal zone is flat, with the exception of the steep coast of Cap Vert, which is of volcanic origin (Statistisches Bundesamt, 1987).
3.3.1 Background information
In 1984, 5.22 mil ha of arable land and permanent crops were registered. Approximately 2/3 of the gainfully employed inhabitants work in agriculture. They produce about 1/3 of the net export profits, especially from groundnuts and groundnut products and to a lesser extent from cotton. Staple foods are millet, rice, maize, beans, cassava and groundnuts. In the densely populated coastal regions vegetables are also grown. Tree crops are oranges, mangoes, bananas, coconuts and oilpalm. (Statistisches Bundesamt, 1987)
The two crops, groundnuts and millet, alone cover 88 % of the cultivated land; they are produced across the whole of the country except for the Senegal river valley. Cotton production takes up only about 1/20. It is found primarily in Senegal Oriental and Casamance. 67 % of the groundnut production originates from Sine-Saloum. Sorghum is grown especially south of Kaolack and rice in Casamance; dry rice is found in Senegal Oriental and paddy rice along the Senegal river. Maize cropping occurs only on a few areas in the south of Sine-Saloum, but mainly in Casamance and Senegal Oriental. Nib cropping occurs throughout the whole country, however is more prevalent near Louga. (Havard, 1988a)
Depending upon the weather conditions the yields of the individual crops fluctuate significantly in different years. On the whole, food production per inhabitant has declined approximately 1/3 in the past 10 years. Under a "new agricultural policy" an increase and diversification of own production of staple foods (millet, maize, rice) is to be achieved with a corresponding reduction of food imports, especially rice. (Statistisches Bundesamt, 1987 and 1985)
Animal husbandry only plays a small role in agricultural production. Cattle are reared predominantly in the north of the country and represent the most important activity with 2.2 mil animals (1985). (Statistisches Bundesamt, 1987)
3.3.2 Status of animal traction
Animal traction is considerably widespread in Senegal. More than 30 % of all the farms use draft animals (Starkey, 1988b). In contrast, in 1984 only 460 tractors and 145 combine harvesters were registered in the country (Statistisches Bundesamt, 1987).
In no other country of francophone Africa in the past has so much effort gone into the promotion of animal traction as in Senegal. For this reason there is hardly an animal-drawn implement in Africa that has not been tested in this country, either in this or a similar version. (Bordet et al., 1988) The dissemination of animal traction here was particularly associated with the expansion of groundnut cropping.
Today, the number of draft animals is given as ca. 520,000, of which 200,000 are horses, 180,000 donkeys and 130,000 cattle (Starkey, 1988b). Since there is a good market for meat of young draft oxen they are considered to be a very economic investment (compare section D 5). In 1981 about 26 % of the draft cattle were cows (Lhoste, 1986). The utilization of cows offers the possibility of having trained animals over a long time span and to assure reproduction (compare section D 1.3.1).
In the This, Diourbel and Louga regions horses represent the greatest share of work animals, while in the south of the country oxen predominate in the Casamance region. Donkeys are used in the north and the east. Correspondingly, one can observe a transition from the donkey to the horse and then oxen with increasing humidity. The suppression of the tsetse fly due to aridity is an advantage for the penetration of the donkey in the south.
3.4 Work operations and implements
Bordet et al. (1988) estimate that in 1983 ca. 230,000 cultivators, 145,000 seeders, 100,000 carts, 67,000 groundnut lifters, 52,000 plows and 9,000 ridgers were being used. These figures show the significance of light cultivators (especially Houe occidentale and Houe sine) and the seeder (Super Eco).
After initially being used for groundnuts and later also for other crops (cotton and grain) the Super Eco was overtaken by light cultivators for weed control and for surface soil preparation in terms of sales figures. (Bordet et al., 1988)
The increase of sales of animal-drawn implements during the years 1960 - 1979 (figure F 12) must be viewed in connection with the "Programme Agricole" operational in this period in Senegal. Credits for procurement of inputs was made available to the farmers within the framework of this scheme, which was discontinued in 1980 because of open debts accrued by some cooperatives (Havard, 1988a). This directly affected a reduction of sales of implements. The decline is less attributed to the lower real demand of the farmers for implements than to the poor capability of building up capital. The farmers reacted by continuing to utilize their old implements in their poor condition, thus negatively affecting the work operations. (Havard, 1985)
The development of animal traction occurred primarily in the "Bassin Arachidier". 82 % of the implements sold since 1950 went to the area, comprising the Thi Diourbel, Louga and Sine-Saloum regions. Sgal Occidental received only 9 % of the total, including however 30 % of the ridgers and plows. Casamance region absorbed 9 % of the sold implements, which consisted of 50 % of the plows and 65 % of the ridgers. Animal traction has not been disseminated in the remaining regions. (Havard, 1988b)
In subsequent sections of this text the plow, ridger, Super Eco seeder, groundnut lifter and multipurpose Houe occidentale, Houe sine, Arara, Ariana and the polyculteur are introduced for each individual work operation. The implements available in Senegal are almost exclusively manufactured by SISMAR in Dakar. This company also offers other implements, which have however hardly found acceptance in agricultural practice. This also applies for prototypes.
3.4.2 Soil Preparation
Soil preparation with a animal-drawn plow was for a long time the object of the extension service programme in Senegal. However, the plow is not accepted by the farmers in the north of the country and in the Sine-Saloum region. The main reason is that the vegetation period is very brief in these drier regions. Sowing must take place as early as possible. A prior intensive soil preparation during the dry season is not possible in the dry and hard soil. Soil preparation after the first rain would delay the sowing date considerably and thus increase the risk for the yield and harvesting.
For this reason direct sowing with the seeder without previous soil preparation is prevalent in the northern drier part of Sine-Saloum, while in the south only a surface soil preparation occasionally takes place with the cultivator.
In contrast, the longer vegetation period in the more humid
areas of Casamance allows a more intensive soil preparation. In this region
crops are traditionally grown on ridges. Here, the plow has been used for
seedbed preparation and to some extent for building up of ridges. A more
intensive soil preparation is necessary, among other things, because of the high
weed growth in wetter regions. Estimates assume that a large proportion of the
plows in Senegal are to be found in this region The practice of superficial soil
preparation, as is conducted in Sine-Saloum, has moved in recent years to
approximately 200 km to the south.
Harrows have not been seen in agricultural practice.
Two plows from SISMAR are being offered: the CFOOOP conventional plow with the Huard body (8" or 10") weighing 38 kg (figure F 14) and a 10" reversible (two-way turnover) plow with 2 bodies weighing 50 kg, which however is not widespread. According to company brochures both plows function at a working depth of 18 -20 cm and an average draft power of 70 -80 kp.
In Senegal the Huard plow body, especially with the CROOOP conventional plow and as a tool for the Arara cultivator, appears to have become widespread. This plow requires a team of animals (as a rule oxen).
SISMAR offers a ridging body, which can be mounted on multipurpose implements. In eastern Senegal and Casamance it is often found in combination with the Arara multicultivator, which is most widespread there. Another ridging body has been introduced from the Gambia to Casamance and is occasionally employed with the frame of the CFOOOP plow, after the "Programme Agricole" was discontinued in 1980 and no further credits were offered. It appears to achieve a better result in some situations. (Fall, 1985 in Bordet et al., 1988)
The Super Eco seeder was already introduced in 1930 for planting groundnuts and had substantial distribution. The implement is equipped with a furrow opener, two seed covering scrapers (adjustable in height) and a press roller. The exchangeable slanting spacing wheel assures a careful handling of the seed, which is particularly important for groundnuts (figure F 15). The deeper point of gravity of the implement and its low weight facilitates handling. For transport the tools can be set to a higher position. The Super Eco is adapted to the draft power of the donkey (25 -30 kp) or horses (35 - 40 kp): with coulter, furrow opener and duckfoot shares it requires 20 kp on sandy soil and 30 kp on soils with a higher clay content (Havard, 1988a).
The implement received a good assessment from all the respondents and contacts. Its success is especially attributed to its appropriateness for direct seeding, which corresponds to the traditional method of sowing in some regions. In addition, the seed covering scrapers mounted on the implement simultaneously take care of weed control during sowing, an operation that is traditionally done by the farmers after the emergence. Seeding can be also done on low ridges because of the two side wheels (Metzger, 1988).
In practice the accessories, such as the knife coulter or the marking stick are not used by the farmers (Bordet et al., 1988). The furrow opener is often welded tight, in order not to become lost, even if it is no longer possible to adjust the working depth (Havard, 1988a).
The pre-condition for the utilization of the Super Eco is a field free of roots and harvest residues. Its use has displaced the work peak from sowing to weed control as a result of the now possible expansion of cropped area. The farmers often sow the greatest possible area and during weed control they can first assess how much they really will manage to tend depending on the climatic conditions (Metzger, 1988).
The Tamba seeder is used for sowing cotton; it deposits the 5 - 6 seeds in pockets at a spacing of 15 -25 cm. The implement is considered inefficient due to the uneven distribution of the seed (Havard, 1988a).
Because of its rapid pace the horse is usually used for sowing. Frequently, children are given the task of seeding and weed control with animal-drawn implements.
The Super Eco has a varying distribution corresponding to the types of crops and cropping methods:
3.4.4 Weed control
This work operation is carried out almost exclusively with multipurpose toolbars having 3 or 5 cultivating tools, which are suited for both weed control and surface soil preparation. In addition, they can be equipped with a ridger, plow body or groundnut lifter.
For the following two implements a width adjustment of maximum 45 cm is possible (the spacing of the groundnut rows is between 50 and 60 cm). As a rule only one draft animal is used for this work operation, normally the horse or donkey. (Bordet et al., 1988)
The Houe Occidentale is a light cultivator. It can be used with 3 or 5 cultivating tools or 3 chisel-plow tines and can easily be adjusted for width without the aid of a spanner. Moreover, a ridger or a plow body (6 or 8") can be obtained for this implement and groundnut lifters manufactured by artisans are often utilized. It weighs 18 - 25 kg. (figure F 16)
The Houe Occidentale has achieved similar success to the Super Eco in Senegal. In contrast to our experience that weed control as a rule is mechanized before seeding with draft animals (compare section E 1.4), the cultivator (here the Houe Occidentale) required a longer introduction period than the seeder. Its wide distribution is however attributed to the fact that the draft power of the donkey is sufficient for the task of weed control, as is the case with the Super Eco.
The Houe Sine is a medium-weight cultivator. The tools can be adjusted in width simply without a spanner (figure F 17). It can be equipped with 3 cultivating tools, 3 chisel-plow tines, a ridger, a plow body (8 - 10") or a groundnut lifter. It is used primarily with cultivating tools. It is also used in combination with the Firdou groundnut lifter, and to some extent with the ridger or plow body (both for draft oxen).
It weighs 30 - 45 kg. Since it was subsidized after 1966 it costed about the same price as the lighter Houe Occidentale, which boosted the sales of the Houe Sine
(Bordet et al., 1988). Cattle and horses are preferred for pulling the Houe Sine.
The only implement used for harvesting is the groundnut lifter; the sales have increased appreciably in recent years There were an estimated 67,000 groundnut lifters in 1983. The low number of lifters in Casamance is attributed to the widespread cropping on ridges; the implement is less suited for this method. The figures in table F 7 reflect merely the industrially manufactured implements. Havard (in Bordet et al., 1988) estimates that 60 % of all groundnut lifters (frame and tools) in Senegal originated from local workshops and the tools (shares) for the majority of the remaining implements from industrial manufacturing are made by artisans. For the past 15 years the same tool model (Arara Firdou) has been sold; it can be mounted on all multipurpose toolbars offered by SISMAR. This a type of sweep share manufactured in 200, 350 and 500 mm widths. The 350 mm share has found the widest distribution. Hand-manufactured shares are often used, which are poorer in quality but 6 - 7 times cheaper than the Firdou. These are the only animal-drawn implements that the farmers can purchase without taking advantage of credit facilities. (Bordet et al., 1988) Arara The Arara multipurpose toolbar was developed initially for groundnut harvesting. The same mounting tools can be used for the heavy frame as for the Houe Sine, aside from the fact that 5 chisel-plow tines can be attached (figure F 18). (Bordet et al., 1988) Also called the Araire the implement weighs 31 - 46 kg, depending upon the mounted equipment. A team of two animals is required for draft power.
The Arara has been distributed as a toolbar for the groundnut lifter in the groundnut region, and for the plow and ridger body in cotton-growing areas. 18,000 were sold by SODEFITEX from 1976 to 1979. Aside from Senegal it has become widespread in Benin, Niger and the Ivory Coast. Since its development was primarily directed to utilization for digging groundnuts it is quite cumbersome to handle for plowing. Further disadvantages are the high draft power required, rapid rusting of the bolts and the necessity of a spanner for mounting the tool to the frame. (Bordet et al., 1988)
The distribution of carts take third place (figure F 12), following seeders and light cultivators. Air-filled tires are used on the carts (figure F 19) offered by SISMAR having various sizes and weights, depending upon the type of animals used. The carts have hardly changed appearance since the independence of Senegal in 1960. Some have been in use for a long time. Often they have been distributed under the auspices of development programmes.
As table F 8 shows, the largest proportion of donkey and horse carts are located in areas where the tsetse fly is less prevalent. The figures do not include the carts manufactured by local artisans, which have been usually built from scrap metal for a number of years.
3.4.7 Multifunctional implements
Most of the above mentioned implements are multipurpose toolbars that have achieved special importance for certain work operations. The Houe Occidentale and the Houe Sine are used primarily for weed control and surface soil preparation; the Arara has mainly become significant in the harvesting of groundnuts. Further multipurpose implements of relevance are: Ariana The implement is heavier and more stable than the Houe Sine and is equipped with wheels on both sides, thus facilitating transport. (figure F 20) It can be used with 6 to 8 hoeing implements, one ridger, 1 - 2 plow body (10"), one reversible plow having two bodies (1/4 turn) or a groundnut lifter. It weights 58 - 92 kg, depending upon the equipment. It corresponds to the Brazilian Policultor 600, which was developed in cooperation with CEEMAT.
The Ariana offers the possibility of working two rows simultaneously when sowing or carrying out weed control. Multi-row implements however have generally not been accepted in practice. At the end of the 1970s the Ariana was sold at a subsidized price which included the plow, ridger, cultivator and groundnut lifter. This entire implement array was cheaper than the package without the plow. At the same time, the Houe Sine with a chisel plow and groundnut lifter was also offered at a subsidized price, equal to 1/4 the price of the Ariana. The tools delivered with the Houe Sine were actually those needed by the farmers. For this reason only a limited number of the Ariana could be sold. (Bordet et al., 1988) All implements are pulled by oxen. Polyculteur (Wheeled toolcarrier) The Polyculteur has hardly been used in agricultural practice. The heavy model, "rand rendement" costs 22 times as much as the Houe Sine and therefore only a few are found. It has been purchased by experimental stations and wealthy farmers. Ariana and Polyculteur are often considered to be status symbols (Pocthier, 1988). If one considers the difficulties occurring with the maintenance and servicing of simple implements and that the supply of spare parts is not attractive to the artisan due to the low distribution rate, then it is understandable why this implement will be found in a defective condition (figure F 21) (for further reasons why the implement has been a failure see Starkey, 1988a). (Photo: Schmitz)
3.5. Regional cropping practices and implement use
Two regions, Bassin Arachidier and Basse Casamance, are now described in more detail.
Three zones are distinguished in Bassin Arachidier. The northern zone (essentially the Thi Diourbel and Louga regions) has 300 to 500 mm annual precipitation (figure F 22). There is practically no primary tillage here. The average farm (carrhas 5.8 ha, with 2 Super Eco, 2.2 cultivators (87 % Houe Occidentale), 1.2 groundnut lifters mounted on cultivators, 1 cart and 2.6 animal spans (80 % horse and 20 % donkeys) (table F 9). (Havard, 1988b)
A middle zone covers a width of 60 km from Fatik via Kaolack to Koungheul between the Isohyeten which have 500 to 600 mm rainfall. Here there is a transition from the Houe Occidentale to the Houe Sine and a higher incidence of the industrially manufactured Firdou groundnut lifter. 80 % of the farms have available the seeder and cultivator implement package for harnessing horses, in part with the groundnut lifter (65 %). (Havard, 1988b)
In the southern zone between the Isohyeten of 600 to 800 mm the donkey is replaced gradually with oxen and the proportion of horses remains the same. Non tillage or some superficial working of the soil is practised. Thereby an area performance of 5 h/ha is achieved. Plowing, which would require 25 h/ha, is not done (Metzger, 1988). In addition, the chisel plow can be used as a cultivator for weed control. The Houe Sine replaces the Houe Occidentale. In the Nioro region, located in this zone, the following array of implements is found: cultivator (1.5 per farm <carrt; especially the Houe Sine), seeder (1.45), groundnut lifter (1.1) and cart (0.58). The plow and the ridger are seldom found here. (Havard, 1988b)
Also, in traditional cropping on the level of manual labour, only a superficial loosening and weed control is done with the "iler" (figure F 24).
In the Basse Casamance region there is a wet and dry climate with an annual precipitation of 1000 mm. Plateaus and valleys alternate; in addition a large flood plains exists.
Animal traction (including for transportation) is utilized on 36 % of the farms in the lower Casamance. Two prevalent cropping systems exist with a varying labour distribution between the sexes: the Mandingue system, named after the Mandingue minority and the Diola system, which represents 83 % of the population (Fall and Ndiame, 1988a):
- the Mandingue system (zone A, figure F 23): In this zone the men cultivate the plateau and the women are responsible for the rice crop. The "donkotong" (similar to the daba for ridged crops, section F 2.5.1) is the hand tool used mainly by the men for soil preparation; the women use the "fanting" (figure F 24). Both tools are hoes. Animal traction is used to a considerable extent, but only by the men for work on the plateau. The plow is the most prevalent animal-drawn field implement, and the ridger is also common. The following array of implements reflects an average distribution rate: 1 plow per 2 farms, 1 Arara with a plow or ridger per 3 farms, 1 Super Eco per 3 farms, 1 Houe Sine per 8 farms and 1 cart per 2 farms (table F 9). (Fall and Ndiame, 1988a)
- the Diola system (zone B, figure F 23): The men are responsible for soil preparation on the entire relief, while the women do the easier tasks of seeding and weeding. The most important handtool is the "kayendo". It is used for building up the ridges on the plateau as well as for rice cropping on the slopes and in the valleys and for harvesting groundnuts. It functions somewhat like a shovel (handplow) and is particularly suited for cropping rice in the flood plain. (Marzouk-Schmitz, 1984)
Animal traction is less prevalent. It first serves the purpose of soil preparation on the plateau, which is done by the men, and secondly the soil preparation in the rice fields tended by the women. With the increasing aridity the Mandingue system moves southwards, so that the women have to work their fields in the valley with the "fanting" when the rainy season does not occur early enough (Lo, 1988). The ridger is the most popular animal- drawn implement. Neither seeders nor cultivators are used because of the ridge cropping. The following array of implements is found: 1 plow per 10 farms, 1 ridger per 3 farms, 1 cart per 5 farms (table F 9). (Fall and Ndiame, 1988a) In the remaining zones (C and D) animal traction is scarcely used and only there where Mandingue or immigrants from northern or central Senegal live (Fall and Ndiame, 1988a).
3.6 Manufacturers and artisans
The implements are almost exclusively manufactured by SISMAR, one of the largest West African metal-working factories. Until 1980 a large percentage of the implements were purchased on credit under the "Programme Agricole". Since 1980 (until 1986), for example, seeders were exclusively and cultivators were predominantly bought in a used condition in the Fatick Department. Only carts were purchased new in significant numbers without loans. Also, groundnut lifters, mainly built by artisans, have been bought new. (Havard, 1987a) According to an analysis of animal-drawn implements, it would have been necessary to replace abrasive parts on 30 to 40 % of the implements, 15 to 20 % of the axles of plow wheels or press rollers and 10 % of the gears and further parts of the dispensor mechanisms on seeders.
The distribution of original spare parts functions very poorly according to Havard (1988a), so that the place of the artisans is of utmost importance. All spares (duckfoot shares, furrow opener, spacing wheels, gears) are available in the towns. These are all manufactured by artisans and cost 1/3 the price of original parts. Only bearings, tires and tubes for the carts must be supplied by the industry. (Havard, 1987a)
Most of the blacksmiths have a very meager supply of equipment. They are able to assemble parts and manufacture simple abrasive parts such as shares. Generally, they have templates for fabricating the most important parts such as duckfoot shares for cultivators and furrow openers for the Super Eco seeder. Only 10 % can do welding (figure F 25) (Havard, 1987a). Smiths having arc welders use various types of welding rods. They can, for example, cut threads, weld breaks in the frame or produce seed hoppers.
The supply of materials is the most serious constraint for the artisans. 60 % have no supply in store, the remaining 40 % can only manufacture spare parts from their material supplies for the stocks. The following list of the commonly used material exemplifies the problem of material supplies: leaf springs from trucks, building steel, sheet metal from old cars and sporadically collected parts. (Havard, 1987a)
Frequently, smiths also work in agriculture. Most of the smiths in Basses Casamance mention this as their most important activity (Fall and Ndiame, 1988b).
Animal traction is widely distributed in Senegal. Due to the rapid succession of climatic conditions the cropping patterns and the sequence of implements used change considerably within relatively short distances. In semihumid/semiarid areas direct seeding is common due to the short vegetation period and favoured by the light soils. Efforts to introduce a more intensive soil preparation have failed here. The draft animals used are donkeys and horses.
Due to the wetter climate very intensive weed control prior to sowing is necessary in Casamance and Sngal Occidentale. Longer vegetation periods allow the use of the plow or ridger prior to seeding. Ridged cropping, which hinders the use of seeders, is widespread. Oxen are used as draft animals. In transitional zones superficial scratching and sowing is practised.
Animal traction is primarily introduced in connection with the Super Eco seeder. In numerous development projects many implements have been tested in Senegal. SISMAR represents the existence of a viable farm machinery manufacturer in the country. Nevertheless, the supply of spare parts functions poorly. However the artisanal system is well developed. The ability of the artisan to repair as well as to manufacture spare parts with the aid of templates has contributed significantly to the wide distribution of implements. A severe constraint is the extremely poor supply of materials.