The existing agricultural or farming systems in different ecological zones of West Africa are designed to produce subsistence food, cash sales and materials for local or industrial use. There is no generally accepted classification of farming systems in tropical Africa, but for convenience a classification which is based on intensity of cultivation and/or animal rearing is presented in Table 11. The various production systems are grouped under (i) traditional and transitional systems, and (ii) modern systems and their local adaptations.
Traditional and Transitional Agricultural Systems
The majority of the farming systems of West Africa belong to this group which range from the extensive (shifting cultivation and nomadic herding) to more permanent and specialized types of farming (compound farms and terrace farming). Shifting cultivation is an extensive agricultural production system in which a cultivation phase on ‘slash-and-burn’ cleared land alternates with a fallow period (Okigbo, 1982). The clearing is done using axes or matchetes and usually only herbaceous plants, saplings and undergrowth are cut. When dry the cut material is burned and the cleared area is planted on the flat or on mounds with crops like yams, rice, sorghum, millet, maize and cassava depending on the ecological zone. The land is cultivated for one to four years after which it returns to fallow. The regrowth of natural vegetation rejuvenates the soil through nutrient cycling, addition of litter and suppression of weeds. The cultivation phase alternates with a much longer fallow phase, ideally 10–20 years. Marked variation in the relative lengths of cultivation and fallow periods have been reported by Nye and Greenland (1960) and Ruthenberg (1974).
In classical shifting cultivation, the homestead of the farmer is relocated near the cultivated fields after each cultivation phase. In practice the situation varies from where the farmer may never return to the same piece of land to situations where cultivation is repeated on the same plots. This cultivation system is ecologically viable in frontier situations where population density is low and fallow periods are long enough to restore soil fertility. Shifting cultivation in the classical sense has all but disappeared in West Africa and Morgan (1980) reported it to be restricted to parts of Ivory Coast and small areas between Nigeria and Cameroon (Figure 10). Nomadic herding is the extensive animal rearing counterpart of shifting cultivation in the savannah and more arid areas is discussed separately.
Fig. 10 WEST AFRICA: MAIN AGRICULTURAL OR FARMING SYSTEMS.
|Pastoralism and sabel fringe cultivation|
|Rotational woody bush fallow|
|Rotational bush/grass land fallow|
CLASSIFICATION OF FARMING SYSTEMS IN AFRICA1
(Okigbo & Greenland, 1977)
|A.||Traditional and Transitional||B.||Modern Farming Systems and|
|Systems||their Local Adaptations|
|1.||(a) Nomadic Herding||1.||Mixed Farming|
|(b) Shifting Cultivation (Phase I), L 10*|
|2.||Bush fallowing or Land Rotation Shifting Cultivation (Phase II) L = 5 - 10|
|3.||Intensive Livestock Production (Poultry, Pigs, Dairying)|
|3.||Rudimentary Sedentary Agriculture. Shifting Cultivation (Phase III) L = 2 - 4|
|4.||Large Scale Farms and Plantations|
|4.||Compound Farming and Intensive Subsistence Agriculture. Shifting Cultivation (Phase IV) L 2||(a) Large scale food and arable crop farms based on natural rainfall.|
|(b) Irrigation projects involving crop production.|
|5.||(a) Terrace Farming: L = 1 – 2||(c) Large scale tree crop plantations.|
|(b) Floodland agriculture L ≤ 1|
|(a) Market gardening.|
|(b) Truck gardening and fruit plantations.|
|(c) Commercial fruit and vegetable production for processing.|
1 Adapted from Whittlesey, 1936; Morgan and Pugh, 1969; Floyd, 1979; Laut, 1971; Benneh, 1972; Greenland, 1974.
where C = Cropping period
F = Fallow period
L = Land use factor
Shifting cultivation has been replaced by more intensive farming systems as the result of increasing population pressure and the shortening of the fallow period. The intensity of cultivation can be measured using the Land Use Factor (L) of Allan (1965) where:
C = number of years of cultivation
F = number of years of fallow
Greenland (1974) reported that intensification of cultivation (Table 11) passes through the following phases:
|System||Intensity of Cultivation|
|Phase I - Shifting cultivation||L = 10|
|Phase II - Recurrent cultivation||L = 3 – 10|
|L = 7 – 10|
L = 5 – 7
L = 3 – 5
|Phase III - Semi-permanent cultivation||L = 2.5 – 3|
|Phase IV - Permanent cultivation||L = 2|
The intensification of production in the farming systems shown in Table 11 can be assessed by relating their L values to those above. Based on the foregoing, the traditional and transitional West African farming systems in which crops are grown and some animals reared are characterized as follows:
Originally farming in West Africa was subsistence orientated. During the colonial era trade in spices, forest products and later cash crops led to increased cash cropping and with increasing industrialization, the production of export orientated raw materials (palm oil, palm kernels, groundnuts, rubber, cotton, etc.). With increasing domestic industrialization many of these raw materials can be sold locally. With increasing urbanization and mobility, the market economy has become well established in West Africa, particularly the need by farmers for money to purchase goods, services and farm inputs which can only be obtained through sales of farm produce. By products of farming (manure, fuel wood, etc.) can also be used. Therefore the objectives of traditional farmers are various and, although food crops still have priority, some commodities are produced specifically for sale.
Traditional West African farming systems consist of several fields in more or less concentric circles round a compound or homestead-garden. (Figures 11 and 12). The homestead-garden is under intensive, permanent production and contains a mix of perennial and annual crops grown in a complex agroecosystem. In the tropical rain forest zone this may attain a multistoried structure approaching that of the tropical rain forest (Plates 2 and 3). In the savannah, it is not so complex owing to lower rainfall but the diversity index usually exceeds that of the surrounding woodland. Fertility is maintained by applying household refuse, crop residues and animal manure. The fields are located at varying distances from the homestead and have fallow periods which increase with increasing distance from the homestead (Plate 4).
In areas where population densities are low, L values on the farthest fields can exceed 10. Where population densities are high, as in southeastern Nigeria or Kano, L values are much lower than 10. Most fields outside the homestead-garden contain useful semi-wild or indigenous trees; these include the oil palm (Elaeis guineensis), the oil bean (Pentaclethra macrophylla) and the African mango (Irvingia gabonensis) in the rain forest zone, and the shea butter (Butyrospermum paradoxum), locust bean (Parkia spp), Acacia albida and Balanites aegyptiaca in the savannah. Fields near the intensively cultivated homestead-garden are generally impoverished and under short periods of fallow (L = 1 – 3) because they are constantly being cropped or grazed with no manure or fertilizer application. More distant fields are more fertile mainly because the period of fallow is longer. There is a tendency for these fields to carry crops which are grown for sale or those which are more easily harvested.
There are specialized cropping systems that take advantage of topographical or microenvironmental variations which occur within the farm. The homestead-garden is usually sited in a dry, upland situation, but nearby may be lowland or valley bottoms (called fadama in the savannah areas of Nigeria or boliland in Sierra Leone) (Plate 5) where rice, vegetables, yams, sugar cane, bananas, taro, etc. may be grown depending on the ecological zone. Crops which require high levels of fertility or greater care like yams, vegetables and cocoyam in the forest zone or tobacco and vegetables in the savannah, are grown nearest to the homestead. The homestead-garden system includes varying numbers of small ruminants, pigs and poultry; cattle, donkeys, camels and horses are kept in tsetse-free savannah areas. Livestock are a feature of the homestead and adjacent areas and they graze on fallows and residues on the harvested fields.
The different production systems compete for labour and resources and to maximize these, different crops or varieties of a crop are grown in the different fields. With distance from the homestead, fishing, hunting and some food gathering increase in importance. This concentric field system is sometimes called ‘land zoning’ (Grove and Klein, 1979), or the ‘ring system of cultivation’ (Ruthenberg, 1980; and Norman, et al., 1982).
Fig. 11 SIMPLIFIED MODEL OF SPATIAL ORGANIZATION OF FIELDS AND FARMING SYSTEMS IN TROPICAL AFRICA. (Adapted from Grove & Klein 1979)
NOTE: Specialised field on land use systems include valley bottoms, terraces, termite mounds etc.
Fig. 12 Schematic diagram of compound farms in relation to associated fields systems in traditional farming systems of the humid tropics of West Africa.
PLATE 2 - Compound or homestead-garden in the Humid Zone, Nigeria
PLATE 3 - Compound or homestead-garden and adjacent plot in the Subhumid Zone, Nigeria
PLATE 4 - Distant open cultivated field in the Humid Zone, Nigeria
PLATE 5 - Distant cultivated lowland fadama in the Subhumid Zone, Nigeria. Note bananas, maize and beds of onions in foreground
Farm sizes are small, generally less than 2 ha, but farms in the savannah are larger than those in the forest zone; in Nigeria in 1965, 82 percent of the farms were less than 2 ha.
Tools are simple and hand operated. There is very limited mechanization although since the early 1930s use of animal power for cultivation, planting and transportation on the farm has been increasing in areas free from tsetse. Use of tractors and tractor-drawn implements is increasing but is of no general significance.
Land is almost always universally cleared by manual cutting and burning. Thereafter there is little or no tillage and crops are grown on the flat, or on mounds or ridges which are manually constructed. Weeding is usually carried out manually. There is increasing mechanical land clearing as a result of the high cost of labour.
West African agriculture is characterized by a division of labour between the sexes, with women specializing is some operations and the men in others. There is often acute shortage of labour on farms due largely to seasonal demand peaks for farm operations and division of labour between sexes and age groups. Shortage of labour is aggravated by rural-urban migration, children attending schools and competition from the non-agricultural sector.
Apart from organic and animal manures very little use is made of chemical fertilizers. Physical and cultural methods are used to control pests and diseases although pesticides are used on some cash crops (e.g. cocoa).
Traditional farming systems are designed by the timing of operations, species grown and resource manipulation to make best use of the prevailing rainfall regime. Although there is some traditional use of water to supplement crop growth very limited use is made of irrigation. It has been estimated that West Africa is currently using less than 10 percent of its irrigation potential.
Many believe that shifting cultivation and nomadic herding are the dominant farming systems in West Africa but, according to Morgan and Pugh (1969), Gleave and White (1972) and Grove and Klein (1979), true shifting cultivation has almost disappeared apart from isolated areas. It has been replaced by the farming systems listed in Table 11.
Crops are usually grown as mixtures, relay intercrops or associated sequences. Crop rotations and sole crops are rare apart from rice and to some extent cash crops like groundnuts, cotton and sugar cane; the more a crop is grown for sale the greater the likelihood of its being grown in pure culture.
While productivity per unit of energy may be high, yields per unit of area are low in traditional farming systems. There is not only a wide gap between attainable yields on farms as compared to experimental stations but also as compared to average and recorded yields in other parts of the world.
Traditional and transitorial farming systems in West Africa are complex and not only involve several species of crop but often include livestock. Although crop production is not a component of nomadic herding there are many examples of complementary and symbiotic interrelationships between farmers and herders (Ruthenberg, 1980; Dyson-Hudson (1972) and Norman, et al., 1982).
Traditional farmers, their wives and farm family members in rural areas usually engage in many paid non-farm activities. Earnings from these activities significantly contribute to family income.
Farming systems in West Africa have reacted to changing circumstances. Changes have resulted from (i) introduction of Asian and New World Crops; (ii) population expansion; (iii) European colonization of Africa and the need for spices and agricultural raw materials for industry; (iv) improved means of transportation and communication; (v) expansion of cassava production into marginal areas where other crops often fail, and (vi) introduction of mechanization into farming and adoption of new techniques. Modern farming systems and their local adaptations, as listed in Table 11, often exist side by side with traditional systems.
The first system of crop production which replaced hunting and gathering was shifting cultivation. In West Africa, as elsewhere, it was an efficient and reliable production system in situations where population density was low. As population density increased, however, fallow periods became shorter and more intensive and semi-sedentary agricultural production systems replaced shifting cultivation. Sedentary agriculture involved settlement in villages and communities in which the homestead became a permanent feature associated with a homestead-garden. The outlying fields associated with each homestead were subjected to different periods of cropping but, when population became very dense, these fields were permanently cropped. It would appear that in almost all parts of the world traditional farming systems centred around a homestead-garden where livestock were kept. The various stages in the evolution of farming systems in which crop production constitutes an integral component are shown in Table 12. Continued intensification of production often resulted in more specialized production systems which required more inputs, more capital, specialized practices and new tools and technology. Animals rarely feature in the specialized crop production systems, except where mixed farming is possible, but Lagemann (1977) showed that animal populations increase with increasing human population density. The animal component of the traditional farms plays a crucial role in the maintenance of soil fertility, without which the permanent farming system used on the homestead-garden and adjacent areas would be impossible. Livestock provide meat and other animal products, form a savings account, utilize household waste and fulfil social and cultural obligations. In almost all the ecological zones of West Africa livestock make a significant contribution to farm income.
According to Monod (1975) “no nomad can exist for long without contact with sedentary peoples.” Monod also observed that even the Tuareg nomads of the Sahara maintain contact with oasis dwellers. Contact with sedentary cultivators makes it possible for pastoralists to obtain food (grains, legumes and vegetables) and sometimes water, fodder, grazing land or even cash for part-time work on their farms. Pastoralists are individuals of distinct ethnic groups and in West Africa they consist of (i) Fulani (or Fulbe) who rear cattle and sheep in the Sudan/Sahel, savannah extends from Senegal to parts of Ethiopia; (ii) Tuaregs with herds of cattle and camels who sometimes live in oases in Mali and Niger; (iii) the Toubou who rear cattle and camels and who may also live in oases in Mali and Niger; (iv) Moors in the Sahara comprising a northern group that keeps herds of camels and a southern one rearing cattle and camels, and (v) Shuwa Arab cattle herders near Lake Chad.
It is common practice for herders to arrange with arable farmers to graze stubbles or crop residues from harvested fields, in return for animal manure. It is also the common practice for farmers like the Hausa, the Mossi or Mende to arrange with the pastoralists to look after their livestock and sometimes graze them during the dry season in distant pastures. Arable farmers, on the other hand, obtain animal products (milk, cheese, leather goods), animal transportation and manure from the pastoralists. The importance of manure in maintaining soil fertility in the absence of fertilizer cannot be overemphasized. Even when cattle owned by arable farmers are grazed by herders, a kind of mixed farming is being practised in which, according to Monod (1975), the herders facilitate the combination of crop production and animal production rather than integrating them.
CHANGES IN CROPPING SYSTEMS IN RELATION TO THE INTENSIFICATION
OF CULTIVATION AND INTEGRATION OF ANIMAL AND CROP PRODUCTION
|Stages in Evolution of Crop Based|
|Remarks and Extent of Livestock|
|Per-humid to Sub-humid Tropics|
|1. Collecting, hunting and fishing||No permanent settlement, some camping places. No cultivation, no rearing of stock|
|2. Shifting cultivation||Homesteads moved as fields shift. Cultivation practised. Some animals especially the dog may be kept. Hunting and fishing still substantial. Has almost disappeared or confined to small areas.|
|3. Recurrent cultivation, bush fallow land rotation||Homesteads permanent and associated with fields and temporary huts in new plots. Fields shift or rotate may be in secondary forest, bush, thicket, woodland or grassland fallow. Homestead or compound garden present with some livestock and cultivated trees and shrubs. Protected or semi-cultivated trees and shrubs present in fields.|
|4. Permanent cultivation|
- compound gardens
- planted short-term fallows and rotations
(b) lowlying areas
- wet rice cultivation
- flood plains cultivation
- valley bottoms and ‘fadamas’
(ii) highland areas
(a) terrace farming
(b) mixed farming
Most widespread permanent farming system. Arable crops, spices, tree crops, etc. and livestock present (cattle mainly in savannah zona). In areas of high population density or confined sites, southeastern Nigeria or Kano close settled zone. Rice zone - Sierra Leone, Senegal, Mali Inland Niger delta decrue and crue systems. Very common in the savannah; animals present in 4 (i) in association with farmers compound.
In defensive positions in highland areas - mountains in Togo, Mandara mountains, and Maku in southeastern Nigeria. Livestock usually present. Mixed farming practised by sedentary Fulani in Futh and Mambilia plateau in Adamawa. Monod (1975) reported expansíon of cattle rearing among horticulture people, e.g. Hausa, Kanuri, Borgu, Waja, Kilka, Kaka and Mambila.
|5. Specialized Cash Cropping|
(a) Smallholder tree crop plantations
(b) Smallholder arable crops
|These cropping systems grow cash crops such as cocoa, groundnuts or cotton almost in pure culture in rotation with other crops.|
|6. Non-agricultural work||Livestock may graze residues of arable crops after harvest but may not belong to the farmer. Some peoples whose ancestors were cultivators often move to other professions and some farmers engage in multiple occupations.|
Based on Ruthenberg (1980), Monod (1975) White and Ybeave (197) Gallais and Sidikou (1978)
When this relationship does not exist the herders may plant a crop of millet before migrating north during the rains, which will be harvested when they return during the dry season. Arable farming peoples like the Kanuri, Hausa, Borgu, Waja, Kibba, Chamba, Kaka and Mambilla often rear cattle and other animals and produce their own manure. With the rapid changes now taking place ethnic groups which were traditionally arable farmers are ready to acquire cattle and pastoralists are increasing their arable farming.
In almost all countries of West Africa national policies in agricultural development have changed very little with respect to integration of crop production and livestock rearing. There has, however, been a shift of emphasis since independence. During the colonial era, priority was given to research, extension, marketing and infrastructural development that enhanced production of cash or export crops to the detriment of the major staples. Since independence many African countries have experienced rising food import bills at a time when they are already having balance of payment problems with high petroleum prices and/or the result of adverse effects of drought. Consequently, emphasis has been shifted from cash crops to food crops. Although during the colonial era higher priority was given to crops than to livestock, considerable efforts were made to control major livestock diseases like rinderpest, bovine pleuropneumonia, trypanosomiasis, East Coast fever, anthrax, contagious abortion and parasites such as helminths and ticks. The alarming losses caused by these pests and diseases reached such a magnitude that greater emphasis was given to veterinary services than to the equally important animal husbandry practices and nutrition. Veterinarians dominated policy concerned with animal production and, even when many of these diseases had been brought under control, low productivity attributable to nutrition and husbandry remained neglected. Sometimes animal breeding and production were grouped into a separate Ministry while crop production, which should include forage and pasture crops, belonged to the Ministry of Agriculture. Thus integration of crop husbandry with livestock production was as difficult as integration of veterinary services with animal husbandry, even though animal health and husbandry were very closely related. Various aspects of agricultural development policies and trends in West Africa were reviewed by a number of authorities including Hance (1958 & 1975), FAO (1961 & 1966), Stenning (1969), Dumont (1966), Wells (1974), etc.
Close to, and following, independence a Society for Rural Development (SONADER) was founded in Benin (then Dahomey) and a similar one (SODEPALM) in Ivory Coast for the production of oil palms. Since independence many agricultural production projects involving government corporations, parastatals, state farms and farm settlement schemes have been implemented; most have been unsuccessful. Very few of these projects were aimed at the smallholder who produced most of the food crops and also some of the cash crops. During the last decade, however, special projects aimed at increased food crop production have been launched and include the Operation Feed Yourself (OFY) in Ghana, The National Accelerated Food Production Programme (NAFPP) in Nigeria which was followed by the Operation Feed the Nation (OFN) and, in 1979, the Green Revolution Programme. Of these the most successful was the NAFPP which aimed at making Nigeria self-sufficient in the production of basic staples (rice, maize, sorghum, millet, cassava and wheat) by (i) encouraging farmers to use fertilizers through a 75 percent subsidy; (ii) improved seed; (iii) construction of agro-service centres for input distribution, processing, storage and purchase of produce, and (iv) provision of loans to farmers. It also involved minikit trials which provided the farmers with the opportunity of becoming involved in on-farm trials and evaluation of technology thereby significantly speeding up adoption and feed-back to research. The programme, however, suffered from shortage of small farmer credit and being followed too closely by OFN and the Green Revolution Programme.
There are currently policy guidelines which could act as an umbrella under which effective integrated crop and livestock strategies could be employed in the development of improved alternatives to traditional agricultural production systems. The current Lagos Plan of Action (OAU, 1981) to which all Economy Community of West African States (ECOWAS) countries, as members of OAU, are signatories, provides such policy guidelines. Pertinent provisions of the Plan which accepts ICL research and development strategies as components of a planned national and integrated natural resources management and utilization programme are:
Self-reliance and self-sustainment in economic growth and development.
Putting science and technology at the service of African development.
Achievement of self-sufficiency in food production and supply.
Preservation, protection and improvement of the environment.
Reduction of reliance on export raw materials and priority to development and growth based on Africa's considerable resources within a coordinated strategy.
Achievement of self-sufficiency in cereals, livestock and fish products.
Realistic agrarian reform as the basis for improved agricultural production.
Enhanced utilization of water for irrigation based on existing and new irrigation schemes.
Integrated development of areas freed from the tsetse fly and improvement of trypanotolerant breeds of cattle.
Intensification of programmes to integrate woodlots and trees in land use and agricultural practices at village level.
Priority in research and development to be given to:
increased production of plants and animals through improved husbandry techniques;
assessment and development of natural resources;
alternative energy sources including use of draught animals, biogas, etc.;
maintenance of the carrying capacity of arid lands and soil conservation;
incorporation of agri-silviculture practices into shifting cultivation.
The above policy provisions in the Lagos Plan do not specifically mention Integrated Crop/Livestock (ICL) strategy in the development of improved farming systems, but various aspects of the Plan such as alternative energy sources and mechanization of agriculture, achievement of self-sufficiency in cereals and livestock, integrated development of areas freed from tsetse flies and the recent interest of governments and the World Bank in integrated rural development have direct and indirect ICL implications. It is the role of scientists in various disciplines to design and conduct research and studies which confirm the beneficial effects of ICL. Priority should be given to the development of appropriate technologies and production systems which can be used by the producer on his farm, priorities which will require political commitment through sound policies and allocation of scarce but needed resources.
Constraints to increased agricultural production by small farmers are the same that impede agricultural development and adoption of integrated crop and livestock production strategy. Many of these impediments are related to the same factors which differentiate various farming systems and have been discussed in detail by Flinn et al. (1974), Ryan and Thompson (1979), Okigbo (1981) and ILCA (1980).
The most important physio-chemical constraints to increased crop and livestock production are related to climatic and other environmental factors.
While there is no danger from low temperatures, high temperatures in the surface soil or in the atmosphere close to the ground of 45°C or above, especially when associated with low humidity, can cause serious stresses that are detrimental to plant and animal life. High temperatures are injurious to seedlings and may have adverse effects on rhizobia and nitrogen fixation. They make vegetation very dry increasing the severity of burning and the spread of fires. High temperatures cause rapid decomposition of soil organic matter with adverse effects on soil texture, nutrient retention properties and the colloidal complex of the soil and increase the rate of evapotranspiration which renders light rains ineffective, causes severe losses from dams and reservoirs and, in irrigated soils, triggers off salinity problems. Uniformly high day and night temperatures contribute to low yields as a result of relatively high losses due to respiration. High temperature associated with high humidity has adverse effects on human work performance and contributes to the poor performance of temperate animal breeds in the tropics.
Tropical rainfall is characterized by high intensity, especially close to the beginning and end of the wet season, which increases the erosion hazard on land where the soil has become exposed by forest clearing and tillage. A very serious and frequent cause of famine in the Sahel is the erratic nature of the rain and unpredictable cycles of drought. In the humid tropics, especially above latitudes 6–7°N, and further inland, one or two weeks of drought may occur after planting. Drought stress is a major cause of crop failure and with high temperatures results in marked yield reduction. Related to rainfall is the constant cloud cover in the humid tropics which reduces photosynthesis and thus productivity. Insufficient sunshine in the humid tropics results in reduced response of crops like maize to fertilizers and is one reason why maize production is becoming increasingly important in the savannah areas, provided that moisture is not limiting. Another aspect of the light factor is photoperiodicity to which some traditional short-day plants are sensitive. The short-day sorghums take longer to mature resulting in high culm yields which provide structural materials for fencing and other purposes. As a result dwarf photoperiod-insensitive improved sorghum varieties may not be accepted by farmers.
Other physio-chemical conditions are related to soils which are highly weathered, acid and of low inherent fertility. These soils are not only fragile but in areas of Guinea, Liberia and Sierra Leone are subject to laterization; under continuous cultivation these soils develop multiple nutrient deficiencies and toxicities, but regular liming may also cause nutrient imbalance and toxicities. The infertility of tropical soils and climatic constraints contribute to the low nutritive value and poor quality of forage. Although the highly weathered soils of the tropics possess good physical characteristics for arable farming, it is these same properties which render them more erodible. Further, the adverse environmental conditions in tropical soils which make large areas marginal for plant growth require large quantities of fertilizers, which may not be economic, to sustain high yields.
Biological constraints are related to the favourable conditions that high temperatures have on pests, diseases and parasites. The extent of the adverse environmental problems (weeds, insects, locusts, trypanosomiasis, etc.) which constrain agricultural production, and various health hazards that affect agricultural development in the tropics have been discussed by Kamark (1976). Human diseases and parasites that affect settlement patterns and productivity include malaria, sleeping sickness, river blindness, onchocerciasis, filariasis, bilharzia (schistosomiasis), meningitis, etc., have rendered parts of the Middle Belt uninhabited and unutilized. There are also animal diseases like trypanosomiasis, rinderpest, foot and mouth disease, theileriasis, East Coast fever, dermatophilosis (streptothricosis) and parasites in both humid and arid areas which make livestock production hazardous. Serious diseases and pests of crops include Swollen Shoot of cocoa, maize rust (Puccinia polysoria), cassava mosaic, cassava bacterial blight (Xanthomonas manihotis), cassava mealybug (Phenacoccus manihoti), green spider mite (Mononychellus tanajoa), sweet potato weevil (Cyles puncticollis), maize streak virus, etc. Weeds cause serious losses in the tropics and rampant weed growth is one reason why farmers practise shifting cultivation. As a result the breeding for resistance to pests and diseases and adaptation to environmental stresses are key objectives in plant and animal improvement.
Despite the relative antiquity of indigenous agricultural production systems in West Africa, the developing countries of Africa have not yet developed the long-term scientific tradition and quality of research necessary to maintain satisfactory growth in technology and its transfer to produce rapid agricultural and economic development. At the time of independence there were, for example, interterritorial research organizations for most major cash crops and food crops but all have been closed down. The exodus of expatriate staff after independence, except for countries like Ivory Coast, weakened the research effort and retarded progress. There is still a shortage of trained manpower. Wherever research has been carried out it has given priority to specialized individual commodity production systems and the solution of problem along separate lines. As a result the complex food production systems which require an interdisciplinary approach have been neglected. Research on food crops did not benefit from local knowledge of traditional farming systems or from the socio-economic environment within which they operate until farming systems research programmes were started at the international and some national agricultural research centres. It is only by using an integrated approach to research and understanding the various interacting components of crop and livestock subsystems that effective priorities and programmes can be identified to establish the potential and limits of ICL production systems. The lack of this orientation has resulted in the unsuccessful attempts to transfer successful technologies from temperate countries and to establish large-scale mechanized farms in the tropics. Thus lack of understanding of the traditional farming systems in Nigeria, in particular the role of livestock, led to over-emphasis on the improvement of indigenous trypanotolerant cattle for milk production and the abandonment, until recently, of the work with these valuable breeds. Lack of knowledge of the role of small animals in traditional production systems led to a wrong strategy in poultry improvement for small farmers which advocated intensive production systems which could only be adopted by the affluent, mainly because there was no economic technology to produce maize and concentrates locally.
Several socio-economic constraints bedevil agricultural development and some of these have hampered exploitation of the existing potential and benefits of ICL. These include:
Lack of the basic statistical data and knowledge of the socio-economic background, the environment, the resources and the management capacities within traditional production systems which can be used as a basis for planning, identifying constraints and priorities and the selection of strategies in research and development in agriculture.
Rapid population growth which, in addition to associated socioeconomic pressures, has outmoded the traditional farming systems to the extent that their underlying scientific base and the economic viability cannot now be understood and appreciated.
The complexity of traditional agricultural production systems, the competition between subsystems and nonfarm components, and the farmers' interest in diversification and the reduction of risk through the achievement of reasonable but sustained yields rather than maximization of the production of one or two commodities.
Land tenure and associated problems of fragmentation of holdings, small farm size, the problems of economies of scale and their effects on the profitability and acceptance of certain technologies like communal land ownership which, although eliminating landlessness, deterred investment in land improvement.
Continuing reliance on simple farm tools and manual labour which accentuates the drudgery of farm work. (Nevertheless, there are limitations in mechanization using animals in areas of high incidence of trypanosomiasis or tractors which most farms cannot afford to buy, maintain, hire or fully utilize.)
Shortage of labour at seasonal peaks of demand due to division of labour between the sexes, relatively low return to agricultural work, rural-urban migration and education for children. As a result farming is left to old men and women with low productivity. Despite this there is a marked underemployment during certain times in the year.
Lack of capital and credit for the purchase of inputs, including draught animals in areas where they can be used, associated with the relatively high cost of fertilizers, pesticides and equipment.
Poor extension services and the inappropriateness of new technologies resulting in a very wide gap between experiment station yields and those on farmers' fields.
Conflicting ideologies about development and insufficient understanding of the socio-economic parameters which control the extent and nature of government involvement in production.
Poor marketing and pricing policies for agricultural products which reduce the incentives that are needed to motivate increased agricultural production. Related to this is the shortage of infrastructure which is required to allow farmers access to inputs, services and markets.
Poor communication among technicians, policy-makers and politicians which results in deficient policy formulation and inadequate allocation of the resources required to achieve national priorities.
Inadequate coordination between research and development policies and lack of integrated programmed which take into account the common resources and environmental endowments of ECOWAS countries.
Farming Systems Research
The most significant development in agricultural research within the last two decades has been the formation of international agricultural research centres and the incorporation of Farming Systems Research (FSR) into research programmes. The purpose of FSR is the study of the farmers' environment as well as the various integrated components of the prevailing farming systems. An understanding of the farming systems enables them to be evaluated, modified and redesigned to fit the needs of the farmer. FSR adopts a multidisciplinary approach to research that gives priority to:
Baseline data collection and analysis of farming systems based largely on collection, collation and evaluation of secondary data which is then updated and made more complete by special surveys.
The study of existing farming systems, farmers' objectives, resources, decision-making processes, input/output relationships, sources of income and constraints to increasing productivity.
The analysis and understanding of the workings of the individual components of the systems and the constraints faced by the farmer constitute the basis for determining research priorities and strategies. This ensures that proposed new technologies and system components are relevant to the farmers' needs and circumstances and have a high probability of adoption.
Experiment station testing and analysis of new technologies based on the results of items 1 & 2.
On-farm testing of promising technologies, the evaluation and monitoring of technology adoption and wherever possible, the introduction of necessary modifications, and the identification of the farm level constraints which are responsible for the yield gap between experiment station and the farmers' fields; this also enhances feed-back to on-station research. On-farm research also facilitates the identification of the various off-farm, infrastructural and policy constraints which interact to determine the success of a farm enterprise.
FSR, because of its multidisciplinary nature and detailed study of the farmers' environment, has made agriculturalists aware of the importance of anthropological, sociological, geographical and economic literature which describes aspects of traditional farming systems ranging from the initial hunting and gathering stage to shifting cultivation and pastoralism, through various intensities of cultivation down to the numerous development projects aimed at modernizing agriculture in the tropics.
Other significant developments include economic assessment of traditional and other farming systems, farmers' decision-making processes, resource utilization and the comparative performance of various systems. There has been an upsurge in the study of livestock and small ruminant production systems in the tropics. Of major importance are the activities, conferences and reports of the Winrock International Livestock Research and Training Centre, the Bellagio Conference on Integrated Crop and Animal Production (McDowell and Hildebrand, 1980) and the research programmes of the International Livestock Centre for Africa (ILCA) and the International Laboratory for Research on Animal Diseases (ILRAD). These two livestock research centres complement the work of 11 other stations coordinated by the Consultative Group on International Agricultural Research (CGIAR) most of which are giving priority to food crop improvement and the development of more efficient systems for their production.
FSR gives priority to socio-economic studies of farming systems, which define the characteristics of various farming systems and constraints to their improvement. Work on production economics has demonstrated why certain technologies fail to be adopted by farmers; at ILCA it was shown that some maize varieties were not accepted because they were not suitable for eating green; in other situations local preference is for white maize instead of yellow. Economic studies have also demonstrated the profitability of different technologies or production systems. Norman et al. (1982) indicated the extent to which valley bottom or lowland (fadama) plots give higher returns than upland areas. Most of the lowland areas of hydromorphic soils in West Africa are unexploited. Related to these are multidisciplinary studies of integrated development of small watersheds which will be discussed in greater detail.
Current Crop-Based Farming Systems Research with Implications for ICL
The results of FSR that are pertinent to the design and development of improved cropping systems in West Africa include:
Intercropping which has been demonstrated to give higher stable yields especially at low input levels than sole cropping. It results in more efficient use of resources and involves more uniform distribution of labour throughout the year.
Intercropping involves a wide range of crop species and different varieties of each species that differ in time of maturity and other characteristics which allow the farmer greater flexibility in management and utilization of resources.
The practice of intercropping satisfies the objective of attaining diversification of production for subsistence on small farms, minimizing risks of failure, and producing some commodities for sale.
In some situations intercropping minimizes losses from pests and diseases and provides better cover for the soil which reduces erosion.
Considerable progress has been made in the identification of compatible mixtures of crops such as maize/cassava, plantain/ cocoyam, yam/maize and sweet potato/pigeon peas for the humid and subhumid tropics and sorghum/millet, maize/sorghum, sorghum/ groundnuts and sorghum/cowpeas for the savannah areas.
Some progress has been made in developing rotations for humid and arid areas. At ILCA, in Ibadan, it has been shown that a viable rotation involving intercropping is maize/cassava followed by cowpeas alone or intercropped with chillies or tomato. It was also shown that cowpea is a better crop than soybean in rotation with maize since it leaves more residual nitrogen in the soil.
Soil fertility studies have shown that for sustained yields fertilizer application is imperative but fertilizer application is not often profitable during the first year after fallow. Some application of organic manure is not only beneficial but may enhance the effects of fertilizers.
A start has been made to study potential fodder species, pasture establishment and herbage productivity (ILCA, 1979a). In addition to the collection of data on grass and legume fodder species, ILCA has identified promising forage and browse plants for use in agrosilvicultural systems in the humid trops.
Recent Developments at ILCA and Cooperating Institutions
The CGIAR centres are giving priority to quantitative and qualitative improvement of major food crops in developing countries in addition to the development of more efficient farming systems for their production by small farmers. The crop improvement programmes are giving priority to increased yield, better nutritional quality and other characteristics but especially resistance to disease and pests, tolerance to environmental stresses and adaptation to various production systems. Emphasis is being given to integrated pest management and various ways of reducing the costs of inputs. Areas of FSR in which significant progress has been made include land development and subsequent cropping patterns, zero tillage, live mulch, alley cropping with leguminous shrubs and evaluation of browse in agrosilvipastoral systems. These are summarized below:
Probably the most crucial problem in the development of a permanent food production system for sustained yields is the development of appropriate techniques for land clearing, land preparation and subsequent soil management. In the humid tropics sustained agricultural production is possible when (i) chemical nutrients removed by crops or otherwise lost during cultivation are replenished; (ii) soil physical conditions are maintained at a favourable level by ensuring that adequate levels of soil organic matter are present; (iii) soil is kept constantly covered and erosion effectively controlled; (iv) soil acidity, nutrient deficiencies and toxic constituents are corrected, and (v) build-up of pests, diseases and weeds are prevented (Greenland, 1975). In West Africa bringing new land into cultivation remains the most widespread method of increasing food production. Clearing new land is now expensive as a result of labour shortage, and many governments are resorting to mechanical clearing for large-scale farms and the use of hired tractor units for cultivation on small farms, although most of the mechanized largescale farms in the tropics have failed because of poor land development and subsequent soil management during cropping. At ILCA priority has been given to the study of the physical, chemical and biological characteristics of the more important soils of the humid and subhumid areas of Africa to provide a basis for evaluating their capabilities under cultivation and different management systems. An evaluation of various manual, mechanical and chemical land clearing techniques has shown that clearing methods and soil management must be suited to the crops to be grown. Soil disturbance during clearing was found to cause serious erosion losses and irreversible soil degradation; manual clearing produced the least adverse effects but was slow and expensive. Chemical methods applied by spraying, ringing or trunk injection with selected chemicals such as 2-4-D or Tordon have been shown to be suitable for pasture establishment, but a shear blade with V-shaped cutting edge proved to be the most appropriate mechanical method of clearing for arable crops. It was economical and, when followed by zero tillage, erosion rates were lower and yields higher than with conventional tillage. With good plant residue management and control of weeds with herbicides, the soil is protected and there is no need for terracing or other expensive soil conservation measures on average slopes. Results obtained in land development studies by ILCA are presented in Table 12 and Figure 13. The no-tillage technique requires that crop residues should be left on the surface. Although it has worked on Alfisols at ILCA, tillage studies at Ougadougou in Upper Volta in the Sahel have shown that tillage is necessary and that tied ridging which conserves moisture increased yields by over 13 percent.
Cover Crops, Organic and Live Mulches
Crop and weed residues are important in reducing erosion and enhancing adequate levels of soil organic matter and water infiltration in the no-tillage system. Experiments by ILCA on degraded soils have shown that soil rejuvenation can be achieved by 1–2 years of leguminous cover which is then killed using a herbicide and followed by no-tillage cropping.
Fig. 13 Comparison of various lengths of fallow in relation to cultivation periods in African farming systems (adapted from Grove & Klein, 1979) in comparison with recent attempts to eliminate long term fallows and achieve intensification through alley cropping.
|CULTIVATION PERIOD||FALLOW PERIOD|
Experiments with industrial waste mulches such as sawdust, rice husks, rice straw and legume husks also indicate that these agricultural by products, which are often burnt or thrown away, can be put to good use.
Interest in living mulch is related to the fact that, although 40–70 percent of the farmer's time in the tropics is spent on weeding, hand or mechanized weeding destroys soil surface structure and exposes it to erosion. Moreover herbicides are expensive and hazardous. Experiments at ILCA in which maize has been grown in living leguminous cover have shown that wild groundnut (Arachis repens), Centrosema pubescens, a forage legume, and the wild Wing Bean (Psophocarpus palustris) are promising (Table 13). The results also show that the live mulch added nitrogen and organic matter to the soil while reducing weed growth. The live mulch technique is suited to high rainfall areas where competition with the crop for water is low. It also facilitates cropping of steep slopes without terracing or bunding.
MEAN GRAIN AND ROOT YIELDS FOR INTERCROPPED MAIZE AND CASSAVA IN RELATION TO LEGUMINOUS COVER AND TILLAGE PRACTICE
|Legume Cover||Maize||Cassava||Treatment||Maize Dry Grain||Cassava Fresh Roots|
|Psophocarpus||5 054||24 047||No-Tillage||4 043||26 027|
|Centrosema||4 914||22 206||Conventional Tillage||4 431||26 813|
|Calapo||3 817||28 519||No Fertilizer||3 882||25 497|
|Stylosanthes||3 228||27 088||With Fertilizer||4 592||27 343|
Source: IITA, Ibadan.
Alley Cropping with Leguminous Shrubs and Browse Plants (Figure 13)
Leguminous cover crops, even when they have been shown to be economically viable and suitable, are not popular with farmers. They fix nitrogen but are not as effective in nutrient cycling in fallows as deep rooted shrubs like Leucaena leucocephala, Gliricidia sepium and Acacia barteri. Experiments have shown that Leucaena leucocephala can be grown in rows (alleys) 4m apart and maize, yams, cassava or cowpeas can be planted between. The Leucaena is periodically pruned and the twigs used as mulch returning nutrients to the soil while protecting the soil and preventing shading of the crop. The Leucaena can be pruned at about 2m and the stems used as stakes for viney crops such as yams; the prunings supply fuelwood.
A cooperative study involves grazing browse plants such as Leucaena, Gliricidia and Ficus spp in alley cropping systems with small ruminants. Preliminary results indicate that this system constitutes an effective way of integrating crops and livestock in a permanent production system.
Socio-Economic Studies of Animal Production Related to Arable Farmers
Sleeper (1978) conducted an economic analysis of breeding and cattle fattening to stratify livestock production in West Africa. This called for planned agricultural land use in which the arid zone is used for extensive grazing, the semi-arid areas are used for extensive production of adapted crops, while the subhumid areas are used for intensive fodder and pasture production; cattle should be fattened near terminal markets or export abattoirs. He showed that (i) under the current scheme bovine traction would not substantially increase farm income; (ii) adoption of small feeding units could substantially increase cash income; (iii) bovine traction will not draw a substantial number of cattle from rangelands as envisaged, and (iv) bovine traction and small unit feeding can increase meat supply. Eddy (1979) conducted a linear programming study of mixed farming among the bush Tuaregs of Niger and showed that farmers in the unfavourable terrain have developed a system of integrated cattle and goat rearing with grain production to minimize the risk posed by drought and fluctuating grain prices on the edge of the pastoral zone between the rainfed agricultural zone and the desert. The Tuaregs, who used to plant millet prior to migrating north with the rains, have been forced by competition with Hausa cultivators and Fulani herders to settle and grow millet, sorghum, cowpeas, and spices in the rains, and tomatoes and onions under irrigation in the dry season. Delgado (1978) investigated mixed farming in the Tenkodogo area of Upper Volta, using bovine traction, which was aimed at providing the farmer with milk, meat, a cash income and manure for increasing crop yields. It was found that the smallholders had difficulty in controlling animals in unfenced fields, and that seasonal labour conflicts occurred between the requirements for stock and for sorghum and millet harvesting. He recommended that policy should be directed toward improving the traditional system in which the sedentary Mossi cattle owners entrusted animals to the Fulani herders. Ware (1979) reported that droughts between 1966 and 1973 forced nomadic Fulani herders in the Diourbol area of Senegal to change to mixed farming by having their older sons grow food crops (millet and sorghum) while the women fattened animals and reared poultry. He noted that the Wolof mixed farmers had developed an east/west pattern of grazing fields in such a way that millet, sorghum, cowpeas, tomatoes, etc. are grown on the western half of a field in a given season: in the next season this area is grazed while the eastern half is cropped. Kline et al. (1969) studied problems of mechanization in tropical Africa and found cattle herders were more reluctant to become farmers that arable farmers were to adopt animal traction. They reported trypanosomiasis and feeding to be problems in maintaining oxen and that the oxplough could be used only for planting and cultivation. These studies of animal production in association with crop production must be taken into account in designing ICL projects, planning, research and training.