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Cover Crops in West Africa / Plantes de couverture en Afrique de l'Ouest
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The subhumid zone of CameroonClimate and soilsIn Cameroon, most of the earlier work on Stylosanthes was conducted on the Adamawa Plateau (Wakwa Animal Research Station, near Ngaoundéré), at an altitude of 900–1 500 m asl (Figure 7). The climate is characterized by a long-term mean annual rainfall of 1 706 mm and a growing period of 240 d. Most of the rain (91%) falls between April and October, with a peak during August and September. The soil in the region is basaltic and slightly acidic (pH of 5.5) and has a clay texture, 4.9% organic matter (OM), 2.3% total N, 26 ppm P (Olsen), and low CEC. The vegetation is typically Guinea savanna, with tall grasses, such as Andropogon, Hyparrhenia, and Pennisetum, and a dense tree cover comprising Isoberlinia doka, Lophira lauceolata, Daniellia oliveri, Parkia biglobosa, Anogeissus leiocarpus, etc. Figure 7.
The subhumid zone of Cameroon. Socioeconomic conditions and cultural featuresThe potential users of Stylosanthes in northern Cameroon are
agropastoralists who own livestock and practice some level of cropping (maize
and sorghum, usually intercropped with cowpea). They are from the Fulani
ethnic group. Unlike their counterparts in Nigeria, they have access to
land, and each family owns up to 10 ha or more. They live in villages in
which the houses are mostly constructed from mud, with grass roofing. Richer
farmers use aluminium sheets. Agropastoralists try to overcome dry-season
feed shortages by practicing transhumance, which imposes more trekking on
the herders and the animals. During trekking, some of the animals die. Farming systems and Stylosanthes managementAs in the Nigerian SHZ, ruminant production on the Adamawa Plateau is constrained by the poor quality and quantity of the dry-season forage, and this situation has led to numerous problems. For instance, breeding, and hence calving, take place year-round. Many calves are born during the dry season, when forage is insufficient; cows are extremely weak and unable to produce enough milk to feed their calves. Not surprisingly, therefore, calf losses are high, and calves that do survive have health problems. In addition, animals that depend solely on natural vegetation for their nutrition suffer severe weight loss during the dry season (Lhoste 1967), with consequent reproductive failures (Voh et al. 1984). Nomadism and transhumance can to some extent compensate for this feed shortage by allowing pastoralists to exploit a wide range of natural herbage, but such a lifestyle removes them from basic social and technical-support services. To reduce the impact of the dry-season feed shortage on animal production, extension officers in Nigeria have been advocating the purchase of supplementary feeds, such as cottonseed cake, at least for animals at risk. However, these products are generally scarce and expensive. Planting forages (such as Stylosanthes) as an alternative was tested at the Wakwa station of the Institut de recherches zootechniques (IRZ, institute of animal research) in 1987, with a view to extending the concept to agropastoralists in the region. The Wakwa station began testing several forage legumes as early as the 1950s (Rippstein 1985), and some, such as S. guianensis, Desmodium spp. and C. pubescens, have been found promising for the region (Yonkeu et al. 1994). However, scientists have never found an appropriate way to use these improved pasture species to suit the needs and capabilities of the traditional herders. Government efforts to improve rangeland and its management have been unsuccessful because range legislation cannot be enforced. The fodder-bank intervention, developed by scientists at ILCA in the SHZ of Nigeria, presents an alternative approach to introducing and managing improved forages (Otsyina et al. 1987). In an effort to test and possibly extend the concept, researchers established a fodder bank, using S. guianensis cv. CIAT 184, at the Wakwa station (Tarawali and Pamo 1992). During the 1987 rainy season, a 4-ha paddock, fenced with metal and live
posts (mainly Ficus thonningii), was cleared, plowed, and harrowed
with a disc harrow. Seed of S. guianensis cv. CIAT 184 was first
scarified in boiling water for 30 s and then sown (broadcast) at a rate
of 10 kg ha-1. This effort was not very successful in the first
year, mainly because the pasture was dominated by grasses. Because of the
scarcity of seed, a new fodder bank could not be established. Instead, the
grasses in the 1987 paddock were hand-cleared, and the areas with poor regrowth
were selectively reseeded. Contrary to Otsyina et al.'s (1987) recommendation,
just after hand-weeding, N–P–K (20 : 10 : 10) fertilizer was applied
to the pasture at the rate of 385 kg ha-1. Animal evaluationResearch on the response of livestock to Stylosanthes is very rare. However, Table 8 summarizes a feeding trial carried out in Cameroon using Stylosanthes hay or silage for Zebu heifers. In general, the heifers showed a preference for hay over silage (Rippstein 1985).
Agronomic evaluationPasture productivityThe S. guianensis in Tarawali and Pamo's (1992) study had an average height of 1.41 ± 0.12 m. A total DM production of 5.5 t ha-1 from grass and Stylosanthes was recorded. The botanical composition indicated that S. guianensis constituted 93.4% of the pasture. The remaining 6.6% was made up of perennial grasses, such as Brachiaria ruziziensis, Hyparrhenia rufa, and Hyparrhenia filipendula. The performance of S. guianensis was very good, given the locality of the site and the poor terrain. According to guidelines developed by Otsyina et al. (1987) for classifying fodder banks (60–100% Stylosanthes = excellent; 23–34% Stylosanthes = poor), the fodder bank in Wakwa was in excellent condition (93.4% Stylosanthes). The DM productivity of 5.5 t ha-1 is comparable to the average DM yield of Stylosanthes (4.0–5.0 t ha-1) obtained in the Nigerian SHZ (Mohamed-Saleem and Suleiman 1986), where the fodder bank was developed. This suggests that, given the soils in the Adamawa region, 4 ha of improved pasture is sufficient for the dry-season supplementation of 15–20 stressed animals. On-farm trials in the SHZ of Nigeria have shown that agropastoral herds with access to Stylosanthes supplementation performed better than nonsupplemented herds (see Table 2). Stylosanthes can be expected to perform even better under Cameroonian conditions. It is worth noting that annual burning of vegetation, whether accidental or intentional, is common on the Adamawa Plateau, especially at the end of the dry season. In this study, a fire that burned all the paddocks of dry grass around the site was stopped by the thick stand of green S. guianensis in the fodder bank. A good fodder bank therefore appears able to resist fire, at least early in the dry season.
Stylosanthes fallowsThe principal constraints limiting cereal production (maize and sorghum) in northern Cameroon (Garoua; see Figure 7) are low levels of OM, deficiency of soil nutrients, Striga infestations, and high costs of inputs. Looking for ways to combat these constraints, the Institute of Agronomic Research (IAR) at Garoua focused on the use of cover crops (Youri, this volume). In the 1992 growing season, four species of legumes were established: Canavalia ensiformis, S. hamata, Mucuna pruriens, and Calopogonium mucunoides. DM production was measured about 4 months after seeding: S. hamata had the highest yield (11.28 t ha-1), followed by Canavalia (8.38 t ha-1), Calopogonium (7.41 t ha-1), and Mucuna (5.02 t ha-1). The outstanding performance of Stylosanthes and the low yield of Mucuna in this study could be related to the fact that the former can thrive under low-P conditions, whereas the latter has a high P requirement (Sanginga, Okogun et al. 1996). In the second year (1993), the leguminous plots and an adjacent natural fallow were planted with maize at two levels of fertilization (0 and 100 kg N–P–K ha-1). The fallow preceded by Stylosanthes gave maize yields of 2.30 t ha-1 (0 kg N–P–K ha-1) and 3.68 t ha-1 (100 kg N–P–K ha-1). The natural fallow yielded the least: 1.22 t ha-1 in unfertilized plots and 2.45 t ha-1 in fertilized plots (Table 9). In a separate experiment in 1991, three species of legumes (C. ensiformis, S. hamata, and C. mucunoides) were each intercropped with maize; a fourth treatment was a maize–maize intercrop. All the legumes were planted 3 weeks after the maize (one row of the legume and two rows of the cereal). In the second year (1992), each of the plots was split into two subplots: one to study the effect of the cover crops on weeds; the other, to evaluate the impact of the respective fallows on a succeeding maize crop. Again Stylosanthes gave the highest maize yields: 2.25 t ha-1 in unfertilized plots and 4.40 t ha-1 in fertilized plots (Table 10). Furthermore, Stylosanthes and Calopogonium provided excellent weed control.
In a trial in which maize was planted following a 1-year fallow of Calopogonium, Stylosanthes, or natural pasture, the legume-based plots yielded 2.21 t ha-1 (+138%) and 1.83 t ha-1 (+115%) more maize grain than the plots that had had a natural fallow (Table 11) (Youri, this volume).
Adoption of StylosanthesStylosanthes guianensis appears to be well adapted to the Adamawa Plateau, and the fodder-bank package currently used by pastoralists in Nigeria stands a good chance of being adopted by small-scale farmers in Cameroon. The Cameroonian extension agency, in collaboration with a Gesellschaft für Technische Zusammenarbeit (GTZ, organization for technical cooperation) team at IRZ, encouraged pastoralists to establish Stylosanthes pastures for their animals. The idea took off in 1987, but it slowed down from 1988 on. Shortage of funds at IRZ meant that support services, such as the provision of seeds to extensionists, were no longer possible. Stylosanthes was also introduced in the Bamenda region of Cameroon (Markon and Bambui; see Figure 7) in evaluation trials as early as 1974. Currently, Heifer Project International (HPI) is promoting the legume for dairy production. HPI is a charitable nongovernmental organization (NGO) committed to integrated agricultural development for resource-poor farmers (Nuwanyakpai, personal communication, 1997(1)). In the researcher-managed trials involving Stylosanthes at IRA–Garoua,
farmers showed interest in the use of the legume for Striga control
and soil improvement, but this on-station–on-farm activity is still
in its infancy. It is hoped that the program will involve more small-scale
producers in the near future, especially if funds for a regional project
involving Cameroon, Central African Republic, Zaire, and maybe Nigeria are
approved by donors (Kounmenioc, personal communication(2)). The subhumid zone of Côte d'IvoireClimate and soilsBouaké in the central SHZ and Korhogo in the northern Guinea savanna are the centres for the adoption of Stylosanthes in Côte d'Ivoire (Figure 8). The average rainfall in the area is 1 000 mm. The soil is the ferruginous-tropical type (N'Guessan 1994); it is sandy, with a high proportion of gravel, and has a pH of about 6.0. Levels of P and N are <5% and 0.4–0.59%, respectively; the level of OM is 1.13% at Kohorgo and 1.55% at Bouaké. All these parameters vary considerably throughout the whole region. Figure 8. The subhumid zone of Côte d'Ivoire. The region is typified by broken savanna vegetation, with shrubs and
trees, such as Daniellia, Isoberlinia, Parkia,
Lannea, and Pterocarpus, and a number of grasses, such
as Andropogon, Hyparrehenia, Digitaria, Cymbopogon,
Loudetia, and Pennisetum. Socioeconomic conditions and cultural featuresThe farmers, who mostly belong to the Baoulé and Senoufo tribes, live in villages and settlements, with about 10 persons per household. The Baoulés and the Senoufos are the landowners around Bouaké and Kohorgo. The economic activities in the Bouaké area are based on crops, whereas those in the Korhogo area are mainly based on crops and to a lesser degree on livestock managed by Fulani herders. The male farmers, who are also the heads of the households, are 25- to 40-years old and have 1–5 children and one or several wives and associates within the compound. Children are sent to government schools, and in Bouaké fees are usually paid from farm income. Medical facilities are provided by the government, but individuals are expected to buy their own drugs. Some of the houses of the richer farmers and those participating in the peri-urban dairy project have aluminium roofing, but many other smallholders in the various communities use grass materials. The roads around the villages and farms consist of laterite, but they are better developed than other feeder roads in northern Côte d'Ivoire. As in Nigeria and Cameroon, the low quantity and quality of the savanna
vegetation, especially in the dry season, precipitated the introduction
of improved pastures, such as those with Stylosanthes, which has
a higher CP content as a result of its ability to fix soil N. Farming systems and Stylosanthes managementThe smallholders who currently cultivate Stylosanthes for dairy production in central Côte d'Ivoire are crop farmers who adopted livestock production after the introduction of the Eco-farms Project (see below). Although they keep other animals (such as chickens, goats, sheep, and pigs) on their farms, other tribes from the north (such as the Fulbe and Malinga, who have extensive farming systems) manage the Baoulé and Senoufo herds. The peasants own both lowland and upland farms and practice mixed cropping, with up to 10 crop combinations on a single farm. Tobacco, soybean, rice, and especially cotton are grown as important cash crops The most common food crops are maize, yam, cassava, pepper, tomato, sweet potato, groundnut, and rice. Yam (usually grown in mounds and heavily mulched) and maize are usually grown as sole crops. Rice and vegetables are generally grown in lowland areas. Farm areas under crops vary from 1 to 5 ha. The high cost or unavailability of fertilizers has forced these farmers to rely entirely on green manures, animal manures, and fallow periods. Farmers who include cotton in their rotation have access to draft animals, fertilizers, and credit through the Compagnie ivoirien de développement du textiles (Ivorian textiles development company). Stylosanthes was introduced and tested in the SHZ of Côte d'Ivoire (Bouaké and Korhogo) more than 35 years ago (Toutain et al. 1994) in an effort to improve the nutritional value of the low-quality natural range and to establish artificial pastures. Most of the experiments, which were mainly on station, focused on S. guianensis cv. Schofield and covered plant behaviour, management, and maintenance; sowing techniques; seed production; performance evaluation; and the importance of these species in livestock-production systems. Low animal prices at that time and damage to S. guianensis cv.
Schofield from anthracnose in 1980 retarded the introduction of this legume
to smallholders. Screening of Stylosanthes varieties later identified
disease-resistant ones, such as S. hamata cv. Verano (Toutain et
al. 1994). Researchers recommended the use of this cultivar, in association
with Panicum maximum (a perennial grass) cultivars C1 and T58,
for future Stylosanthes-based pastures to discourage attack by
fungal diseases (favoured by high Stylosanthes densities and humidity)
and to take advantage of low-cost production techniques. In a new set of
evaluation trials, the S. guianensis cultivars CIAT 184, L348,
L359, and IRI 1022 were found to be high yielding and anthracnose tolerant
(N'Guessan and Dosso 1995). Eco-farms ProjectThe Eco-farms Project was jointly established by the Côte d'Ivoire government and Germany, through GTZ. The project sought to create a supply of milk around big cities to reduce the importation of dairy products, which had become very costly; intensify agricultural production; and create jobs for youth. The project got under way in 1987 through the extension support of the Société pour le développement des production des animaux (SODEPRA, society for the development of animal production) and GTZ; the general mandate of both agencies was to promote integrated animal production, with special emphasis on milk. SODEPRA, which ceased to function in the 1980s, was later replaced by the National Agency for the Support of Rural Development (NASRD). Côte d'Ivoire's Institut des savanes (savanna institute) supported the on-farm pilot studies with research and expertise. Eight farmers around Bouaké were initially selected for this project. They focused on the production of milk for the city, and they were each given 10 crossbred cows, a shed, a borehole, 10 ha of Stylosanthes-based pastures, and a farmhouse, where the participant lived with his immediate family. In the past, installing such a structure cost 5–7 million CFA francs (XOF), but after the devaluation of the XOF, the same model was expected to cost around 10 million XOF (Eco-Farms Project 1995) (in 1986, 320 XOF = 1 United States dollar [USD]; in 1998, 610.65 XOF = 1 USD). Under this scenario, the farmer provided all the land required, and the facilities were provided to him on a loan-recovery basis. To establish the improved pastures, the project workers prepared the
land with a tractor and then broadcast S. hamata cv. Verano seed
(5 kg ha-1), in association with P. maximum cv. C1 or
T58 seed (each at 5 kg ha-1). N–P–K (10 : 18 : 18)
was applied at the rate of 300 kg ha-1 to boost the performance
of this grass–legume mixture in the initial year. The dairy animals
were encouraged to graze the pastures year-round. Animal evaluationInterviews with about eight adopters and extension agents revealed that daily milk yields varied from 2.5 to 5.0 L per cow, but a systematic study jointly conducted by GTZ and NASRD in 1994/95 reported that, on average, the N'dama x Abondance crossbreds each produced 5.5 L d-1, although some yielded up to 9 L in one milking. Table 12 shows the excellent potential of the crossbreds to be exploited for milk and beef production. For instance, one dairy cow produced about 1 500 L of milk over 235 d of lactation. The weight of the calves at birth was 25 kg, although some were up to 30 kg. At 1 year, a bull weighed 230–300 kg, equivalent to the LW of an adult N'dama.
Economic evaluationSome of the farmers collected up to 90 000 XOF month-1 from this enterprise (Kaligha, personal communication, 1997(3)), and such an income enabled them to pay school fees for their children, increase their herd sizes, and buy other farm inputs. A systematic economic analysis conducted on six farms during 1994/95 demonstrated that milk accounted for 68.2% of the total income, followed by beef (20.6%) and crops (11.1%) (Table 13). The total revenue from each farm varied from 0.74 million to 1.78 million XOF, with a mean of 1.25 million XOF (Figure 9). This evaluation was based on variable inputs, such as seed, herbicides, fertilizers, labour, feeds, veterinary drugs, and fuel. The income included sales of milk, meat from both large and small ruminants, poultry, and crop produce.
The Eco-farms Project at Bouaké had the initial aim of ensuring
that each farmer earned a revenue of 0.72 million XOF year-1,
which would be equivalent to the income of their counterparts in the towns.
Three years after installation, each farmer was able to earn a total revenue
of 1.50 million XOF year-1. These interesting economic results
— the regular and attractive revenue and the new perspectives of domestic
dairy production, especially after devaluation — are some of the factors
that prompted the further expansion of the Eco-farms Project around Bouaké.
Stylosanthes as improved fallowIn Bouaké, NGOs (for example, the Société de développement des forêts [society for forest development]) are promoting the use of cover crops, including Stylosanthes around Bouaké, mainly to reclaim land abandoned to aggressive weeds. In this system, the land is prepared with a tractor, and S. guianensis cv. CIAT 184 is sown in pure stands at the rate of 10 kg ha-1; N–P–K (10 : 18 : 18) is applied at the rate of 300 kg ha-1 during the establishment year. The following year, the legume is plowed under, and the land is cropped with a cereal. The assessment of crop performance following various periods of Stylosanthes fallow is still in its infancy, but previous on-station work in the SHZ of Côte d'Ivoire (N'Gguessan 1994) established the potential of using such fallows to boost crop yields and restore soil fertility. That study was conducted in Bouaké and Korhogo to assess the residual effects of S. hamata cv. Verano and S. guianensis cv. Cook, with or without fertilizer-N and fertilizer-P, on a subsequent maize crop. The legumes were grown from June 1982 to November 1983. Maize was planted the following wet season, which commenced in May 1984, after the legume biomass had been incorporated into the soil (relay cropping). For simplicity, only the results for the unfertilized Stylosanthes plots will be reported here. Maize yields on plots preceded by S. hamata were 450 and 1 300 kg ha-1 in Korhogo and Bouaké, respectively; on plots preceded by S. guianensis, 1 000 and 1 400 kg ha-1 (Figure 10). Although these are preliminary results, they reflect the potential role of Stylosanthes in agricultural intensification. Adoption of StylosanthesStylosanthes was introduced in the SHZ of Côte d'Ivoire about 35 years ago, mainly in on-station evaluation trials. These initial materials were obtained from the Commonwealth Scientific and Industrial Research Organisation (Australia), the International Centre for Tropical Agriculture (Columbia), the Food and Agriculture Organization of the United Nations (Rome), and ILCA, now ILRI (Ethiopia). During those pioneer days, further extension of these leguminous pastures to farmers was inhibited because of the susceptibility of S. guianensis cv. Schofield to anthracnose in 1980. Following intensive evaluations, some disease-resistant or -tolerant varieties were identified, notably S. hamata cv. Verano and S. guianensis cv. CIAT 184. This successful evaluation program was supported at Badikaha (80 km from Korhogo) by a commercial seed-multiplication farm established to supply high-quality Stylosanthes materials to livestock owners, including adopters of Eco-farms in Côte d'Ivoire and other West African countries (Table 14). On this farm, Stylosanthes was sown on 183 ha, and a seed yield of about 100–300 kg ha-1 was reported for 1986.
Records and recent visits have shown that between 1987 and 1995 in Côte d'Ivoire, eight farmers each adopted 10 ha of Stylosanthes-based pastures around Bouaké to promote the dairy enterprise. It is expected that Stylosanthes pastures will be established between 1996 and 1998 for 30 farmers in central, 13 in southeast, and 13 in west Bouaké, making a total of 56 new adopters and 560 ha, although there have been 90 applicants (Eco-farms Project 1995; Mill, personal communication, 1997(4)). Funds for this new phase will be provided by the African Development Bank (ADB) and GTZ. The recent application of Stylosanthes in fallow management will also increase this acreage during the same period. The West African Rice Development Association (WARDA) and its national
partners are testing S. guianensis cv. CIAT 184 and S. hamata
in rice-based systems in Côte d'Ivoire (four sites) and Burkina
(two sites) and on lowlands (irrigated off-season crop in Vallée
du Kon, Burkina) and flooded plains (Boundiali, Côte d'Ivoire). If
successful, this has the potential to improve many hectares of land in the
region (Becker, personal communication, 1997(5)). The subhumid zone of southern MaliClimate and soilsThe SHZ in southern Mali is situated between latitudes 10 and 14°N and longitudes 4 and 8°W (Figure 11). The rainy season lasts from June to October and is followed by a dry period, which lasts from October to May. This dry period is divided into a cool spell, which is dominated by the harmattan, a cold wind from the Sahara desert (December to February), and a hot spell (March to May). The average rainfall is 750 mm in the northern part (San), 980 mm around Koutiala, and up to 1 300 mm in the Sikasso area. Figure 11. The subhumid zone of Mali. The soils are of the tropical-ferruginous type, with low levels of N and P and a low CEC. The typical toposequence comprises uplands, steep slopes, colluvial soil, banks, and lowlands. The vegetation in the cultivated areas is the savanna type, with large
trees, such as P. biglobosa, Acacia albida, Adansonia
digitata, and Butyrosprmum parkii, all of which are useful
to people. Other common vegetation includes Pterocarpus, Combretum,
Isoberlinia, and Deutarium. The grasses are Andropogon,
Loudetia, Schoenefeldia, Hyparrhenia, and Pennisetum.
Socioeconomic conditions and cultural featuresThe farmers in southern Mali live in village communities in Sahelian houses built of mud. The farmers are predominantly from the Minianka, Senoufo, and Bambara tribes. Population densities are high, and annual population growth rate is greater than 3%. The main economic activity is cotton production, which represents 20–30% of the cultivated land. Each household cultivates about 2–3 ha of cotton. The cotton is sold through cooperatives to the government for export and is Mali's main foreign-exchange earner. The enterprise is very well organized, and the farmers get very good prices for this crop. Over the years, this undoubtedly has improved the standard of living of the indigenous farmers, and they have developed a good knowledge of agricultural techniques. Average cotton yields are up to 1 100 kg ha-1. About 70–80% of the farmers have at least a full team of oxen (plow, harrow) and a donkey-drawn cart; most of them own motorcycles, ox-drawn carts, and wheelbarrows, all of which make farm operations more efficient. The smallholders tend to keep large herds, as this confers social prestige in the community. The farmers consider cattle herds a reliable option (compared with banks) for investing money generated from cotton. Southern Mali is not traditionally a cattle-husbandry zone, but the introduction of cotton, accompanied by animal traction, led to the growth of herds. Because of their Islamic background, the children attend Koranic schools, usually situated in bigger villages. Hospitals are provided in towns, and mobile clinics usually visit the villages. The main problems affecting the communities are low soil fertility and
land degradation caused by the expansion of cultivated lands, with few or
no possibilities for fallow; roaming animals; lack of high-quality forage
during the dry season; poor management of traction animals, labour, and
equipment; disintegration of social unity within farmers' associations;
and a tendency toward the breakup of extended families. Farming systems and Stylosanthes managementThe farmers in southern Mali depend on rain-fed agriculture. They produce cereals such as millet, sorghum, maize, and fonio, generally intercropped with cowpea. The main cash crops, in order of importance, are cotton, maize, rice, and groundnut. Cotton is usually grown in biennial and often triennial rotations with cereals. This farming practice is meant to benefit the food crops, for which no fertilizer inputs are usually provided; in contrast, the cotton usually receives N–P–K and cattle manure. Planting is done on ridges with adjacent furrows, which have the dual advantage of conserving water and retaining fertilizer. The grain yields are variable and tend to decline over the years. The farmers compensate for the low yields by increasing the area under cultivation; to prepare the land, they use animal traction and apply cattle manure. The smallholders keep herds of 25–200 cattle, and these animals provide meat, milk, and traction. In addition, farmers also keep small ruminants (usually up to 20 or more), which usually satisfy the financial, social, and religious needs of the people. The herds depend on natural pasture during the wet season, then mainly on crop residues at the beginning of the dry season. These are supplemented with cottonseed cake (produced locally by the cotton industry) in the late dry season. Although produced locally, the cottonseed cake is reportedly still inadequate to support the growing cattle population in southern Mali. For instance, the cottonseed cake produced by the cotton mills in Koutiala and Koulikoro meets about 10–30% of the demand in southern Mali. Part of this cottonseed cake enters the commercial circuit and leaves the area for other regions in the country. Some farmers have been encouraged by extension workers to exploit Stylosanthes pastures for late dry-season supplementation of their cattle and small ruminants and to improve the nutritional status of their traction animals before commencement of land preparation. In the past, the use of improved pastures to feed animals was very rare in southern Mali. The farmers usually establish Stylosanthes as sole crops, with guidance from farming-systems research scientists and extension agents. The land is mainly prepared by traction animals, and scarified seeds are broadcast at the rate of 10 kg ha-1. Fertilizer (Phosphate naturel de TilemsiTM [PNT]) is applied at the rate of 300 kg ha-1 at planting. Some farmers cut the legume and carry this fodder to the animals, whereas others use the improved pastures for grazing their animals. Because of the legume's soil-improving characteristics, crops are usually
introduced in Stylosanthes plots 3 years after establishment, to
exploit the residual effect of the legume. Land reclamation at the Dalabani seed-multiplication farmThe national seed-service farm was established at Dalabani (near Bougouni) by the Malian government to promote the production and distribution of high-quality seeds (cotton, rice soybean, cowpea, maize, sorghum, etc.) for crops grown by the cotton farmers in southern Mali. Continuous seed production commenced in 1975 but had to be stopped in 1992 because of the general decline in seed yield for all these crops. This was a result of soil degradation caused by lack of rest periods and failure to use amendments, such as cattle manure. Cover crops were then introduced, mainly to restore the fertility of the degraded soil on the farm. The usual seed-production activities of the farm were transferred to private-contract farmers, and the farm was planted with Stylosanthes spp. Aeschynomene, Panicum, etc. Fifty hectares of the land was specifically planted to Stylosanthes, and 22 ha of this was dedicated to seed-multiplication plots. The initial seed stock was purchased from the defunct Badikaha seed farm in northern Côte d'Ivoire, at a price of 4 000 XOF kg-1. Seeds harvested from the farm are usually sold to farmers and NGOs through the regional offices of the Compagnie malienne de développement des textiles (CMDT, Malian textiles development company). The yield varies from 200 to 300 kg ha-1, and the Stylosanthes residue is fed to traction animals. The farm in Mali is able to produce Stylosanthes seeds for any organization in West Africa, provided the order is received in advance. There is clear evidence (a high density of nitrophilous grasses) that
the previously degraded soil has been rejuvenated, and the farm manager
is now planning to go back to crop-seed production, in rotation with Stylosanthes-seed
production. About 200 farmers visit the farm each year. These observers
reckon that the idea of revitalizing the farm through cover crops is wise,
and some of them promised to try it on their farms. Animal evaluationResearch in Mali is currently focused on agronomic evaluation; however,
farmers are evidently using Stylosanthes to promote dairy production
and the performance of traction animals, and the legume seems to be having
positive effects on both enterprises. In the CMDT zone around Koutiala,
farmers allow work oxen to graze Stylosanthes before or after 2–3
h work. Agronomic evaluationIn effect, it is the responsibility of the Institute of Rural Economy (IRE), and more specifically, the Division of Research for Rural Production Systems (DRRPS), to carry out the research and extension programs with a multidisciplinary team of scientists in three zones: the CMDT zone around Sikasso, Koutiala, and San; the CMDT zone at Bougouni; and Operation High Valley (OHV) zone, around Banamba, Koulikoro, Kati, Kangaba, and Bamako. All these extension bodies have been collaborating with other organizations, such as the Agro-ecological Project, the battle against erosion project (PLAE), and CMDT, to evaluate Stylosanthes in the farming systems of southern Mali. Some of these activities are summarized below. In 1986, some herbaceous legumes, including Stylosanthes, were established in three villages (Tominian, Koutiala, and Fonsébougou); PNT was applied at three levels (0, 300, and 600 kg ha-1). Some combinations of herbaceous legumes used were B. ruziziensis + S. hamata and Cenchrus ciliaris + S. hamata; pure S. hamata and natural vegetation were also in the trials. In the OHV zone, 11 villages have had improved Stylosanthes fallows since 1989. After 2 years, the improved fallow produced more DM (6.3 t ha-1) than the natural fallow (4.1 t ha-1), but the forage value was more or less the same, and the N content improved only slightly (Table 15) (DRRPS 1990).
Between 1987 and 1988, ILCA carried out feasibility studies on fodder banks at three sites: Madina (4 ha), Diassa (4 ha), and Sotuba (near Bamako; 6 ha) (ILCA 1989). The banks, which consisted of Stylosanthes fallows, were meant to secure supplementary feed for livestock during the dry season. At each site, the land was plowed, fertilized with SSP (120 kg ha-1), and seeded with S. hamata (10 kg ha-1). After 2 years of establishment, Stylosanthes-based pastures yielded up to 10 200 kg ha-1 (71% stylo) at Sotuba, 5 500 kg ha-1 (87% stylo) at Madina, and 6 129 kg ha-1 (25% stylo) at Diassa (Table 16). The establishment of the fodder bank was preceded by several tests meant to identify species adaptable to different sites in southern Mali. Stylosanthes guianensis was the most productive, followed by Stylosanthes scabra and then S. hamata. However, the first two species were susceptible to anthracnose and were therefore abandoned in favour of S. hamata.
In a peri-urban dairy program, jointly conducted by ILCA and IRE to improve milk production in Bamako, fodder banks consisting of Stylosanthes were established in four villages (Falan, Sanankoroba, Bancoumana, and Tienfala). The DM productivity was disappointing at all four sites in the first year, as a result of late seeding. However, in the second year, the yield was appreciable at all the locations (Table 17).
Crop productionDRRPS conducted on-farm trials on the effect of Stylosanthes and Brachiaria on soil fertility and the grain yield of subsequent cereals in the CMDT zone. The cover crops were planted either as sole crops or in combination in 1988. After 3 years, the plots were sown to sorghum. Soil analysis showed that after the fallow period, soil fertility had improved in the Stylosanthes plots, as was evident from better C–N ratios. For instance, the C–N ratio changed from a range of 22–25 to one of 8–12, signifying an improvement (Diarra and de Leeuw 1994). Grain yield of sorghum from soils preceded by the legume was also clearly better than that from non-Stylosanthes plots (Table 18) (DRRPS 1990).
Economic evaluationA simple economic analysis of data from an SHZ site in Mali suggested that peasants' adoption of Stylosanthes generates a net income of 55 480 XOF ha-1 (Table 19). Fomba and Bosma (1994) concluded that the surplus cereal produced as a result of soil improvement does not guarantee the financial attractiveness of the system and that extension schemes should focus on the optimal use of fodder by livestock in addition to crop yield. In Mali, as in Nigeria, the analysis indicated that fencing constitutes the highest expense (about 41%) in the package. Where the cotton industry is thriving, it may be more profitable to follow up an improved fallow with a cash crop, such as cotton, rather than with a food crop.
Similarly, an economic analysis based on linear programing confirmed
that the adoption of S. hamata by farmers in southern Mali increased
their incomes, provided a reliable market exists for animal products (Kébé
1994). In this evaluation the Stylosanthes system produced more
animals (1029 tropical livestock nnits [TLUs] as opposed to 759 TLU) and
more manure. The extra revenue generated from the sale of meat also provided
the necessary capital to purchase inputs required for maize production.
This analysis considered inputs such as land, labour, ox-plow, and cart;
animal products and crops were considered the outputs. Adoption of StylosanthesIn southern Mali, the testing and diffusion of Stylosanthes owes much to the efforts of research and extension agents, in addition to those of DRRPS and CMDT, which actually have the national mandate for this. A summary of these efforts is given below to illustrate the potential for adoption of this legume. Stylosanthes was introduced in 1974 to supply fodder and to reactivate degraded soils in Mali, mainly in the cotton-growing belt of the south. As already indicated, in 1986, Stylosanthes was tested in Tominian, Koutialia, and Fonsébougou. ILCA established three fodder banks at Madina, Diassa, and Sotuba between 1987 and 1988. In 1989, OHV introduced improved Stylosanthes in 11 villages, and in 1990, the peri-urban dairy team around Bamako established Stylosanthes in four villages (Falan, Sanankoroba, Bancoumana, and Tienfala). Promoting the technology, PLAE distributed 200 kg of S. hamata
seed in 1991/92 to be used to establish sole pastures in 25 villages (Diarra
and de Leeuw 1994). In the 1992/93 promotion, the same project distributed
1 000 kg of Stylosanthes seed in southern Mali. Preextension Stylosanthes programFaced with the constraints of maintaining soil productivity in southern Mali, DRRPS farming-systems scientists, in conjunction with CMDT extension agents, started testing Stylosanthes on farmers' fields in four villages (Kola, Karangana, Ségain, and Touroumadié) around Koutiala and Sikasso in 1989/90 (Fomba and Bosma 1994). The three principal objectives of this preextension phase were to evaluate the Stylosanthes system under farm conditions, determine the degree of adoption by farmers, and determine the support services required by the extension agents to successfully pass this message to farmers and fulfill their requirements, for instance, in the supply of seeds. The introduction of Stylosanthes usually commences with a sensitization of farmers and the choice of voluntary farmers from each village. This is followed by a demonstration session on the establishment of Stylosanthes and live hedge enclosures to protect the legume; usually this session is organized by training agents. Subsequently, the sites are visited by other farmers from the village. The use of live fences is encouraged because wire fencing is very expensive. Euphorbia balsamifera and Jatropha curcas were used in this preextension program, as these species performed well in a previous program in the battle against erosion. Stylosanthes seeds were unavailable in Mali to commence this extension program, but they were eventually acquired from NASRD (Côte d'Ivoire) at 4 000 XOF kg-1. The same organization provided cuttings of Euphorbia free of charge. After 3 years of activities, the preextension program ended with 49.3 ha covered. Of the original 310 participants, only 59 were still using the technology (Table 20). The dramatic drop in the number of participants could be related to the problems indicated by farmers in the Siwaa zone (see below).
During the evaluation, the farmers were asked to choose the three main problems they intended to combat using Stylosanthes. The problems the farmers cited generally depended on the particular situation of the village. For instance, restoration of soil fertility was perceived as an important issue in all the villages except Touroumadié, where land is always available (Table 21). Fodder production was also considered by all the villages to be important, except at Kola, where the farmers are busy combating soil erosion. At Touroumadié, because of the paddy fields, the problem of fodder should not be expected to be as acute as in any of the other villages, but the fact that the animals appreciate Stylosanthes explains the importance accorded to its production.
Transfer of Stylosanthes technology to farmers in the Siwaa zone by CMDTThe experience derived from the preextension exercise was very important for CMDT extension agents, who were already encouraging farmers in all the 25 CMDT sectors in the region to use Stylosanthes. The new program, which involved 45 farmers, was initiated in 1992 in the Siwaa zone, with the hope that the exercise would be extended in later years to other areas of southern Mali. The Siwaa zone covers two districts (Molobala and Koutiala) and six villages: four in Molobala and two in Koutiala. To stimulate Stylosanthes-seed production and to test the willingness of the farmers to pay for the seed, CMDT supplied it on the condition that the farmers would reimburse CMDT in the second year. After 1 year, 49% of the farmers abandoned the program (Dembélé and de Vries 1993). Poor development of fodder during the first year and lack of follow-up by the trainers were two factors in the farmers' withdrawal from the scheme. Constraints that hindered the expansion of Stylosanthes in the Siwaa zone included lack of protection from roaming animals; ignorance of the types of species available; and lack of professional techniques for cutting, conservation, feeding, and seed collection. Stylosanthes germination was good for 61% of the plots owned by the farmers who continued in the program but for only 27% of the plots owned by the farmers who withdrew. Also, management practices varied widely between the two groups. For instance, most of the farmers (72%) who opted out of the program planted the legume very late (October), whereas the majority of those (61%) who continued planted their Stylosanthes at the appropriate time (July). Fifty-nine percent of the farmers who abandoned their Stylosanthes plots paid no attention to fencing, but this was true of only 33% of those who continued. More live hedges were used by the latter (23%) than by the farmers who lost interest (9%). 1M. Nuwanyakpai, HPI, Cameroon, personal communication, 1997. 2J. Kounmenioc, IRZ, Cameroon, personal communication, 1997. 3M. Kaligha, Agence nationale d'appui au developpement rural, Côte d'Ivoire, personal communication, 1997. 4E. Mill, GTZ, personal communication, 1997. 5M. Becker, WARDA, personal communication, 1997.
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