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Cassava production in Africa is used almost exclusively for consumption as food. In fact, 95 percent of the total cassava production, after accounting for waste, was used as food in Africa in the late 1990s14 In Africa, total cassava consumption more than doubled from 24 million tonnes per year in the early 1960s to 58 million tonnes per year in the late 1990s (FAOSTAT). The large increase in the total cassava consumption in Africa is due to a significant increase in per capita consumption in countries such as Ghana and Nigeria where cassava is produced as a cash crop for urban consumption. The availability of cassava in a convenient food form, such as gari, played a major role in the increase in the per capita cassava consumption in Ghana and Nigeria. Future increases in cassava consumption in other African countries will depend on how well cassava is prepared into food forms, which make an alternative to wheat, rice, maize and sorghum to urban consumers.

Cassava roots are the single largest source of calories in seven African countries having 40 percent of the population in the late 1990s'15 . In these seven countries, cassava contributed an average of nearly 600 calories per person per day. In another 11 countries with about 25 percent of Africa's population, cassava was the second largest source of calories16 . In those countries, cassava provided more than 300 calories per person per day in the late 1990s (FAOSTAT). Thus, in Africa, cassava roots are an important source of calories for about 65 percent of the total population.

These averages underestimate the importance of cassava in specific countries. In the Congo, for example, many families eat cassava for breakfast, lunch and dinner. In the Congo, cassava contributed over 1 000 calories per person per day or about 55 percent of the average daily calorie intake in the late 1990s (FAOSTAT). Cassava leaves are widely consumed as a vegetable in several places where cassava is grown such as in the Congo and Tanzania. Since cassava leaves are rich in protein, vitamins A and C and some minerals (iron and calcium) (Latham, 1979, p. 172) they partially compensate for, the shortage of these nutrients in the roots.

Cassava was found to be the cheapest source of calories among all food crops in each of the six study countries. As family incomes increased, the consumption of cassava as dried root flour declined while consumption in convenient food forms such as gari increased. Dried cassava root flour is cheaper than gari because of the high cost of processing gari. Medium and high income families were found to consume gari because it is cheaper and more convenient to cook than grains. The future of cassava as a rural and urban food staple will depend on cassava's ability to compete with wheat, rice, maize, sorghum and other grains in terms of cost, convenience and availability in urban markets. Cassava can retain its competitive edge only through investments in labour-saving production, harvesting and processing technologies.


The income elasticity of demand estimates for cassava products were found to be positive at all income levels. For some cassava products, the income elasticity of demand was above one (Table 5). For example, in Nigeria, it was surprising to discover that the income elasticity of demand for gari was significantly higher than that of maize at all income levels. Among high-income urban households, the income elasticity of demand for gari was also higher than that of rice. In Ghana, the income elasticity of demand for cassava (all products combined) was higher among urban than rural households. These estimates provide convincing evidence that cassava has a strong market demand in the COSCA study countries.

Table 5. Income elasticity of demand for cassava and other food staples for rural households in Nigeria, Tanzania and Uganda; rural and urban households in Ghana

StapleNigeria'Tanzania *Uganda lGhana 2
 All Sample HouseholdsLow Income HouseholdsHigh Income HouseholdsAll Sample HouseholdsLow Income HouseholdsHigh Income HouseholdsAll Sample HouseholdsLow Income HouseholdsHigh Income HouseholdsRural HouseholdsUrban Households
All cassava0.780.840.760.770.800.661.
Fresh roots1.
Gari0.850.850.77--- --- 
Dried roots0.550.570.530.750.800.661.171.151.13- 
Yam0.910.900.92 - - -- 
Sweet potato---0.970.970.740.790.64---

1. COSCA study, Ezemenari et al. 1998 and Nweke et al. 2001

2.Alderman 1990

The conclusion that emerges from the new data presented is that in Africa, cassava is not an inferior food. Rather, in certain forms, cassava is superior to some grains. Gari has substantial market demand among low-, medium- and high-income rural and urban households. The degree to which the future market demand for cassava for food consumption can be expanded however, would depend largely on the extent to which the quality and variety of cassava food products can be improved to make them attractive to a range of consumers in rural and urban centres.

The measures needed to reduce the cost of making cassava available to consumers in convenient food forms include:



In Africa, cassava is not widely used in the livestock feed industry. For example, in Nigeria in the late 1990s, only 1.5 million tonnes of cassava (5 percent of total production) per year was used in the livestock industry compared with 9.8 million tonnes (50 percent of total production) per year in Brazil (FAOSTAT). In Nigeria, the amount of cassava used in the livestock industry increased from 0.56 million tonnes per year in the mid 1980s after the Government banned the importation of maize in 1985/86 and feed mills were forced to use local raw materials such as cassava. After the import restrictions on maize and other crops were removed in 1995, there was no incentive for feed millers to reduce the quantity of cassava they were using because cassava is cheaper than maize and farmers were getting higher yields from TMS varieties.

In Nigeria, the 5 percent of total cassava production that is used as feed is significantly lower than in Brazil (50 percent) because in Nigeria, cattle, sheep and goats are free grazed and pigs rummage on household waste. Also the poultry industry only has 125 million birds in Nigeria as compared with 867 million in Brazil in 1998 (FAOSTAT)18.

Due to the pessimistic outlook for a major increase in cassava fed to livestock in Nigeria, the logical step is to examine the global outlook for Nigerian cassava exports for livestock feed. The key country to examine is Thailand because it has dominated the export of cassava pellets for livestock feed for more than three decades.

Beginning in the 1960s, the Government of Thailand encouraged private firms to set up private pellet factories and produce cassava pellets for export to the EU (European Union). Exports increased from 100 000 tonnes in 1966 to a peak of nine million tonnes in 1989. However, due to competition with U.S. grain exports to the EU market, the price of cassava pellets has declined, making it unattractive for Thailand to produce cassava for export. Due to low prices, Thailand did not meet its export quota from 1994 to 1998. In fact, Thai pellet exports declined from 9 million tonnes in 1989 to 3 million tonnes in 1998 (Ratanawaraha et al., 1999, p. 18).

The EU has allocated a quota of 145 000 tonnes of dried roots per year to the World Trade Organization (WTO) members excluding China, Indonesia and Thailand. This quota has never been reached. In Ghana, some entrepreneurs sought to exploit the opportunity offered by the WTO quota (Graffham and Westby, 1999). Exports of dried roots from Ghana increased from about 1 000 tonnes in 1995 to over 51 000 tonnes in 1996 (FAOSTAT). In 1997, world cassava prices fell from US$150 to US$100 per tonne. In Ghana in the same year, the price of the dried roots for food stood at US$0.13 per kg when the exporters were willing to pay only US$0.04 per kg to producers (Graffham and Westby, 1999). Consequently, the exports of dried roots from Ghana declined to 36 000 tonnes in 1997; 7 000 tonnes in 1998; and less than 5 000 tonnes in 1997 (FAOSTAT). The implication of all this is that faced with depressed world prices of cassava, African cassava producing countries should concentrate on expanding the use of cassava in livestock feed at home rather than trying to break into the EU market at this time.

What can be done to increase the use of cassava in livestock feed in Africa? In Nigeria, a poultry feed trial has shown that if cassava roots and leaves were combined in a ratio of four to one, the mixture could replace maize in poultry feed and reduce feed cost without a loss in weight gain or egg production (Tewe and Bokanga, 2001). If this important research finding is diffused and adopted by farmers and livestock feed producers, the amount of cassava used in livestock feed in Africa would increase. At present, cassava leaves have no market value except in countries such as the Congo and Tanzania where the leaves are consumed as a vegetable19.


Technologies exist for the use of cassava as a partial substitute for wheat in bread-making and biscuits, pastries and snack foods manufacture (Satin, 1988, Eggleston and Omoaka, 1994, Defloor, 1995 and Onabolu et al., 1998). In Africa, the amount of cassava used for food manufacture by the food industries is insignificant. For example, in Nigeria in the late 1990s, an insignificant 3 tonnes of cassava was used per year for food manufacture compared with maize, 133 000 tonnes (FAOSTAT). Use of cassava as a partial substitute for wheat in food manufacture will increase if the practice can result in a reduction in the prices of the manufactured composite cassava and wheat flour food products compared with the prices of the same products made with 100 percent wheat flour.

In Africa, due to an array of reasons, the composite cassava and wheat flour food products are not cheaper than the 100 percent wheat flour food products. For example, a partial substitution of cassava for wheat in bread flour requires expensive supplementary viscosity enhancers such as eggs, milk and gums to compensate for the lack of gluten in cassava (Eggleston and Omoaka, 1994, Defloor, 1995 and Onabolu et al., 1998).

Using cassava flour for bread-making and for the manufacture of biscuits, pastries and snack foods requires a reliable supply of cassava flour with constant quality (Delfoor, 1995). In Africa, cassava flour available on the market varies widely in quality because of the wide range of traditional methods of preparation used. Cassava flour of standard high quality will be more expensive and will increase the cost of the food products.

Other important factors such as the cassava variety, age of the cassava root and the cassava growing environment also influence the quality of the food products in which cassava flour substitutes partially for wheat flour (Eggleston and Omoaka, 1994 and Defloor, 1995). Measures to standardize cassava varieties, age of cassava roots and the cassava growing environments will further increase the costs of the food products in which the cassava flour is used to substitute partially for wheat flour.

In Nigeria, the technologies for the use of cassava as a partial substitute for wheat flour in food manufacture that were developed at IITA and other research centres were adopted by food industries when wheat flour was made scarce by the wheat import ban in the mid 1980s. When the wheat import ban was removed in the mid-1990s, however, the food industries readily reverted to the use of 100 percent wheat flour in food manufacture (Bokanga and Tewe, 1998).

In Africa, the increase in the use of cassava in food manufacturing industries does not depend on technologies for partial substitution of cassava flour for wheat flour in bread, cookies and pastries, etc., but the increase in the use of cassava in food manufacturing industries requires the development of technologies for industrial manufacture and packaging of traditional African cassava food products, which have a snack value such as gari, attieke and chickwangue.

It was explained earlier that in Africa, past attempts to manufacture gari and chickwangue industrially failed because they were unprofitable. In Brazil, however, recent development in the use of cassava in food industries shows that sustained investment in research and development can make industrial manufacture of 100 percent cassava starch traditional food product profitable. For example, the main cassava-based fast food in Brazil is pao de queijo, a type of bread made with sour cassava starch, which has been fermented and dried (Vilpoux, Olivier and Marco Tulio Ospina, 1999).

In Brazil, the preparation of pao de queijo by traditional methods has similar problems as the preparation of gari, attieke and chickwangue in Africa. For example, in Minas Gerais, one of the traditional pao de queijo production states in Brazil, almost every family has its own recipe. Sour starch gives pao de queijo a very acid taste, which is appreciated in the Minas Gerais state. In other states however, where consumption is more recent, people prefer pao de queijo with a mild taste. Sour starch is important in pao de queijo preparation because of its expansion characteristics, which result from the combined action of fermentation and sun-drying. Industrial manufacture of pao de queijo needs a standard product with consistent quality. These criteria are difficult to maintain in pao de queijo because of the low and unstable quality of sour starch. Making sour starch is labour-intensive. The sour starch industry is competitive with a large number of small producers. The small capacity limits the possibility to access modern technologies and market information (Vilpoux, Olivier and Marco Tulio Ospina, 1999).

Through sustained investment in research and development, pao de queijo was transformed from a small-scale home-made product to a large-scale factory-manufactured product by first replacing fermentation and sun-drying with a chemical process in making the sour starch. Later, the sour starch was replaced with other types of cassava starch which are acceptable to consumers. Since the early 1990s, the preparation of pao de queijo by small-scale manufacturers in the traditional production states such as Minas Gerais has been declining while larger more modern companies are expanding in other states. The entrance of large companies changed most of the industry. The operators of the large companies have better education, better access to new technologies and market information.

In Brazil, the research and development in the improvement of pao de queijo were carried out mostly by the private sector. The expansion in the consumption of the pao de queijo was facilitated by political support. For example, the consumption was endorsed by the former President of Brazil, Itamar Franco. He required that pao de queijo be present at all official meetings. Since the mid-1990s, Brazilian consumption of pao de queijo has increased greatly, changing from a regional to a nationwide fast food. It is also possible to find pao de queijo in other South American countries such as Argentina and Peru (Vilpoux, Olivier and Marco Tulio Ospina, 1999).

To summarize, there are technologies for use of cassava as a partial substitute for wheat in food manufacture. In Africa, cassava is not used for food manufacture because food products made with 100 percent wheat flour are cheaper and preferred by consumers. Sustained investment in research and development on industrial manufacture of African cassava food products such as gari, attieke and chickwangue which have snack values can lead to the increased use of cassava in food manufacturing industries.


In Nigeria in the early 1990s, only about 700 tonnes of cassava starch was produced per year because Nigerian cassava starch is considered to be of low quality by Nigerian industries and none is exported. In the mid-1990s, cassava starch only accounted for 5 percent of the 17 000 tonnes of starch used each year as industrial raw material in Nigeria (RMRDC, 1996). The bulk of the starch used as industrial raw material during the mid-1990s was imported corn starch which represented 80 percent of the total. The remaining 15 percent was an unspecified type of starch. The quantity of industrial starch used in Nigeria in the late 1990s was low. Even if most of it was made from cassava, the impact on the total demand for cassava would be small.

The scope for increasing the use of cassava starch in Nigeria's industries is to a large extent, limited by the ready availability of high quality imported corn starch and Nigeria's meagre research and development investment in preparing cassava starch for industrial uses. Nigerian private investors do not have the incentive to invest in cassava research and development because of the lack of patent protection. Also, Nigeria's industries that use starch as a raw material have access to cheaper and higher quality starch from imported sources.

Table 6 illustrates the potential industrial uses for cassava and research priorities for developing cassava starch and dried cassava roots as industrial raw materials in six different industries in Nigeria: textile, petroleum drilling, pharmaceutical, soft drink, beer malt and ethanol/alcohol industries. The potential is high in three industries.

Table 6. Nigeria: Industrial potential for cassava and research and development priorities

IndustryCassava-based Raw MaterialPotential for Increasing Cassava UtilizationRequired research and development activity
TextileCassava starch in direct formMediumImprove the quality of cassava starch by improving the method of drying cassava roots
Petroleum drillingCassava starch in direct formMediumMake cassava starch gelatinize in cold water
PharmaceuticalCassava starch hydrolysates including glucose, maltose, sucrose, fructose and syrupMediumSet up industries to make glucose, maltose, sucrose, fructose and syrup from cassava starch
Soft drinksSyrup concentrateHighPrepare syrup concentrate from cassava starch and test it for suitability for making soft drinks
BeerDried cassava rootsHighDevelop a method of making beer malt using dried cassava roots
EthanolDried cassava rootsHighSet up cassava-based small-scale alcohol units; and carry out feasibility study of producing ethanol from cassava in Nigeria and ethanol from cassava in Ghana.

Source: Nweke et al 2001

The first is syrup concentrate for the soft drink industry. In Nigeria, the soft drink industry is dominated by Coca Cola which imports the syrup concentrates and keeps them as a trade secret. Syrup concentrate has been successfully made from cassava starch by IITA post-harvest technologists. A pilot project is needed to determine its acceptability and potential profitability in making soft drinks.

The second potential use of cassava is in the beer industry. Beer has been brewed in Nigeria with imported barley malt for many decades. However, in 1985/86, Nigeria banned grain imports and the brewery industry began to produce beer malt with sorghum produced in northern Nigeria. The initial concern that sorghum beer would not be acceptable to consumers proved to be without basis as beer consumption did not decline after sorghum malt was used to replace barley malt. The Nigerian beer industry currently uses about 200 000 tonnes of sorghum each year to make beer malt (RMRDC, 1996). No attempt has yet been made to prepare beer malt from dried cassava roots produced in southern Nigeria where most of the beer industries are based. However, biochemists at the National Root Crops Research Institute (NRCRI) believe that given the right enzyme, it is possible to prepare beer malt from dried cassava roots. The manager of the Golden Guinea Brewery, Umuahia believes that consumers would accept cassava malt beer judging from their ready acceptance of sorghum beer in the mid 1980s. However, the manager reported that Golden Guinea would be reluctant to invest in research on making beer malt from cassava roots because patent law is not enforced in Nigeria. Research is needed to develop the technology for making beer malt from dried cassava roots.

The third potential for cassava as an industrial raw material is a cassava-based alcohol industry. Currently, Nigeria imports about 90 million litres of alcohol annually with about 80 million litres being used by the liquor industry. If the 80 million litres were produced from cassava, it would require 500 000 tonnes of dried cassava roots which would increase the demand for cassava, raise farm income, generate on-farm and off-farm jobs and save foreign exchange. However, a cassava-based ethanol industry should be of more help to other cassava producing countries that import petroleum because Nigeria is subsidizing the retail price of gasoline. A feasibility study should be carried out to determine the economics of a cassava-based alcohol industry in Nigeria and a cassava-based ethanol industry in other African cassava producing countries that import petroleum.



Historically, many scholars have asserted that cassava depletes the soil. For example, Hendershott, et al., reported that cassava is well known not only for producing large quantities of carbohydrate, but also for exhausting the soil (1972, p.60). Similar assertions have been made by Davesne (1950), Irvine (1953) and Grace (1977). Soil fertility is a subject of major importance in a discussion of expanding food production in Africa (IITA, 1998). Human-induced land degradation is severe in Africa. Numerous researchers claim that a lack of replenishment of nutrients is leading to rapid deterioration in soil fertility. Fertilizer use is low because of high transport costs, late delivery and the risks associated with food production in marginal areas (Pinstrup-Anderson et al., 2000).

To test the hypothesis that cassava depletes the soil, COSCA researchers collected soil samples from 1 501 fields planted with staple crops in 281 villages in the cassava growing areas of the Congo, Côte d'lvoire, Ghana, Nigeria, Tanzania and Uganda. The soil samples collected over the 1991 to 1992 period revealed that the amount of clay, silt and sand did not differ between cassava fields and the levels found in the fields of other crops20. In fact, soils of cassava fields were higher in total N, organic matter, Ca, Na, TEB, ECEC and pH21.

A twenty-year cassava yield-experiment conducted by S. K. Hahn at IITA's high rainfall station at Ibadan in the transition zone from the early 1970s until the early 1990s found that the yield dropped significantly from an average of 40 tonnes per ha during the first four years and then stabilized at around 20 tonnes per ha from the fifth to the twentieth year. Cassava was grown every other year in a two-year rotation without chemical fertilizer. Hahn concluded that cassava produces a large amount of foliage which is recycled as manure to the soil. Hahn's landmark twenty-year study shows that cassava yields are sustainable under continuous cultivation. The COSCA soil survey and Hahn's twenty-year yield experiment provide evidence that the assertion that cassava depletes the soil is a half-truth.

The myth of cassava being a soil depleting crop may be attributed to the fact that cassava is widely grown in the forest zone where high rainfall and sandy soil accelerate organic matter decomposition, leaching and soil erosion at a faster rate than in the transition and the savannah zones22. For example, an eight-year experiment in the forest zone of Ghana revealed that cassava yields declined under a continuous rotation of cassava and maize with fertilizer. In the transition zone, a similar experiment was carried out without the application of fertilizer and cassava yields declined but at a slower rate than in the forest zone (Nye and Greenland, 1960 cited in Odurukwe and Oji, 1981).

The myth of cassava as a soil degrader has been used to downgrade cassava's role as an environmentally friendly crop. Cassava cultivation entails minimal soil disturbance especially in light soils which are susceptible to wind or water erosion. Cassava is normally grown on flat land in sandy soils and on ridges and mounds on heavy lateritic soils (Hahn, 1984). The plant provides soil cover so long as it grows; as a semi-perennial it does not shed all its leaves with senescence. As a semi-perennial, cassava plants serve as a planted fallow. Although there are places, especially high population density and market centre areas, where cassava is harvested from six to 12 months after planting, the normal time of harvest is 12 months or more. The cassava plant protects the soil by providing cover and recycles nutrients by shedding old leaves as it grows.

To summarize, in Africa, increased production of cassava will not lead to environmental degradation because contrary to conventional wisdom, cassava does not deplete the soil more than any other crop. Cassava is often grown on flat seedbed with minimum tillage. It produces a large amount of foliage which is recycled as soil nutrient. As a semi-perennial crop, cassava provides year-round soil cover.


Cassava has been described as a women's crop by some scholars (Ikpi, 1989 and 1989a and Okorji, 1983). For example, Okorji (1983) found in the Abakaliki area of southeast Nigeria that women owned more cassava fields than men and concluded that cassava is a women's crop. COSCA researchers collected data from six countries and found that the categorization of cassava as a women's crop is a misleading half-truth that is based on anecdotal evidence and isolated village studies.

The COSCA studies show that the proportion of the household cassava field area (hereafter field) owned by women ranged from 4 percent in the Congo to 24 percent in Côte d'lvoire23. By contrast, the proportion of cassava fields owned by men ranged from 15 percent in Côte d'lvoire to 72 percent in Uganda and 81 percent in Nigeria. Joint ownership by both men and women account for the balance of the percentages in each country.

There is an important exception in tree crop-dominated rural economies. Among the six COSCA countries, women in Côte d'lvoire owned a higher proportion of the cassava fields than men. In Côte d'lvoire and in most other tree crop dominant-farming systems, the men concentrate on producing tree crops such as cocoa and coffee. Hence, although there are specific locations in certain countries where women owned more cassava fields than men (Okorji, 1983 and Ezumah and Domenico, 1995), these locations are exceptions and not the norm.

The COSCA studies found that both men and women make significant contributions of their labour to the cassava industry in most of the COSCA countries. However, men and women were found to specialize in different tasks. Men worked predominantly on land clearing, ploughing and planting while women specialized in weeding, harvesting, transporting and processing (Figure 3).

Figure 3. Percentage of cassava fields in which men, women, or men and women together, provided the bulk of labour for different tasks, average for six COSCA study countries

Figure 3

Women were found to contribute less than half of the total labour inputs in the cassava system in five of the six COSCA study countries (Nweke et al., 2001). The exception was the Congo. Therefore, it is a vast overstatement to categorize cassava as a woman's crop. In fact, both men and women play strategic but changing roles during the cassava transformation process. As cassava becomes a cash crop produced primarily for urban centres, men increase their labour contribution to each of the production and processing tasks. For example, the proportion of the cassava weeding carried out by men was higher in Nigeria than in Tanzania because in Nigeria, cassava is produced as a cash crop for urban consumption and in Tanzania, it is a famine-reserve crop (Nweke et al., 2001).

The COSCA studies found that the introduction of labour-saving technologies in cassava production and processing has led to a redefinition of gender roles in the cassava food system. In Nigeria, on farms where land clearing or ploughing was mechanized, men increased their labour inputs in planting, weeding and harvesting. In Nigeria, as the processing tasks became mechanized, the contribution of male labour to cassava processing increased because men operated all of the processing machines. When processing became mechanized, women shifted their labour to production tasks such as weeding and men managed the mechanized processing tasks.

The last two observations of the COSCA study challenge the validity of the claim that women's workload increases relative to men's as commercialization of agriculture proceeds.

The COSCA studies also found that women who wanted to plant cassava were not constrained by the lack of access to new cassava production technologies or to essential production inputs such as farmland, planting cuttings of the TMS varieties and hired labour. Both men and women were able to plant cassava on land that they had inherited, purchased or rented. Finally, although most of the cassava processing machines were owned by men in most of the COSCA countries, both men and women had access to the machines by paying a fee to the machine owners.

The COSCA studies show that the assertion that cassava is a women's crop in Africa is not valid because men are more important in terms of the ownership of cassava fields. The myth is also rejected because in terms of work in cassava fields, women do not produce more cassava than men in most of the COSCA studied households.

What are the policy implications that flow from these observations? Although there are persistent calls by donor agencies and gender experts on African policy-makers to hire more female agricultural extension workers in cassava growing areas, COSCA research shows that both men and women play significant and changing roles in the cassava food system in Africa.

Country specific studies are needed to determine appropriate policy measures for use of cassava to improve the welfare of men and women in Africa. For example, in Ghana and Nigeria where cassava is produced as a cash crop, more men are staying in the villages and working in cassava production and gari processing. Similarly, in the Congo, men are also staying in tree crop-producing villages and working on cassava for home consumption because they earn higher cash income from tree crops than from employment in urban areas. Outside the tree crop areas, young men migrate out of the Congolese villages to escape rural poverty. Women are therefore left to produce food for their families under conditions of extreme rural poverty.

The solution to poverty and low returns to both men and women engaged in cassava production and processing is to take a holistic approach and introduce improved varieties and processing technologies to improve the economic returns of cassava production and processing and drive down the real (inflation adjusted) price of cassava in rural and urban markets.


Historically, cassava has been a subsistence crop when 90 to 95 percent of the people in Africa were in farming. Today, although only half to two-thirds of the people of Africa live in rural areas, there is still a myth that cassava is primarily a subsistence crop that is grown for home consumption by farmers and rural net food buyers. The increasing urbanization and consumer demand for convenient food products in Africa has stimulated the urban demand for cassava products such as gari and attieke. To meet the expansion in demand, cassava has emerged in many countries as an important cash crop for farmers and as an urban food staple.

The percentages of cassava fields planted for sale in the six COSCA countries were as follows: the Congo, 59; Côte d'lvoire, 51; Ghana, 57; Nigeria, 45; Tanzania, 32; and Uganda, 25. In the Congo, the proportion of cassava planted for sale was higher than for any other crop (Tollens, 1992). In Nigeria, the Congo and elsewhere, there are small-scale farms that produce 5–10 ha of cassava entirely for sale (Berry, 1993).

Table 7 shows that cassava is an important source of farm income in the COSCA study countries, but particularly in Ghana and Nigeria. In both Ghana and Nigeria, cassava cash incomes were the highest among farms with access to mechanized cassava processing equipment for the preparation of gari. The contribution of cassava to farm incomes was found to be low in Tanzania and Uganda because the majority of farmers in both countries lacked access to improved cassava processing equipment. In the COSCA study countries, cash income from cassava accrued to more households than cash income from any other food crop, confirming the relatively egalitarian spread of benefits from the production of cassava (Table 8).

The COSCA data from 281 villages in the six most important cassava producing countries in Africa dismiss the myth that cassava is a subsistence crop produced by and for rural households. Cassava is increasingly being transformed into a cash crop that is produced and marketed as an urban food staple in many countries in Africa. This discussion illustrates the need for measures to increase the productivity of the cassava food system in order to raise the income of farmers and those involved in processing and marketing and reduce the real cost of cassava for consumers over time.


Increasing the productivity of the cassava food system can help both the rural and urban poor by driving down real (inflation-adjusted) cassava prices over time. However, since Africa's independence in the 1960s, cassava has been neglected by African policy-makers and international donor and development agencies because cassava is erroneously considered an inferior food, the consumption of which will decline if incomes increase in Africa. It is now time to focus sustained African and donor attention on the entire cassava production and utilization system and develop action plans to accelerate the cassava transformation. The solution to poverty and low returns to the men and women engaged in cassava production and processing is to concentrate on introducing improved varieties, agronomic practices, labour-saving harvesting and processing technologies and finding new industrial uses for cassava. There is a need to remove subsidies on imported rice and wheat in order to provide a level playing field for cassava in the food system.

Table 7. Percentage distribution of cash income of cassava producing households by source in Côte d'lvoire, Ghana, Nigeria, Tanzania and Uganda, 1992

SourceCôte d'lvoireGhanaNigeriaTanzaniaUganda
Cash Income Per capita (US$)1141081775148
Food crops1555551628
Cooking banana00032
Sweet potato00102
Other food crops0171947
Other crops*7621202511

US$ 1 = 266 CFA; 430 Cedi; 17 Naira; 285 Tsh.; 1 118 Ush

* Other crops means industrial crops such as cotton, etc. and tree crops such as cocoa, coffee, oil palm, etc.

Source: COSCA study

Table 8. Percentage of COSCA study households which earned cash income from food crops in the Côte d'lvoire, Ghana, Nigeria, Tanzania and Uganda

CropCôte d'lvoireGhanaNigeriaTanzaniaUganda
Cooking banana130913
Sweet potato117618

Source: COSCA study

Without question, increased cassava production is a powerful but incomplete engine of rural economic growth. The fuel that drives the cassava transformation is the introduction of biological and mechanical technologies coupled with institutional innovations and balanced food policies. The introduction of new technology creates new bottlenecks which have to be broken by further innovations and changes in policies. Several examples illustrate this substitution process at work. The spread of the TMS varieties in Nigeria has shifted the labour constraint from the production to the harvesting task. The biological control of the mealybug shifted the control programme to the green spider mite and to the Ugandan variant of the mosaic disease. Likewise, the substitution of mechanized for hand grating has shifted the labour constraint to peeling. The lack of knowledge of the gari preparation technology has restricted its use in the Congo, Tanzania and Uganda. Finally, the lack of the knowledge of how to prepare cassava leaves has prevented consumers in Côte d'lvoire, Ghana, Nigeria and Uganda from taking advantage of the nutritional value of the cassava leaves in their diets.

The TMS story illustrates the substitution process at play. The TMS varieties have boosted yield by 40 percent without fertilizer application. Cassava producers in Nigeria are demanding mechanized harvesting technology to reduce the harvesting labour bottleneck created by the high yield of the TMS varieties. The TMS varieties attain a maximum yield in 15 months after planting but commercial farmers in Nigeria are demanding varieties that will achieve a maximum yield in 12 months or less in order that they can practice continuous cultivation of cassava.

To address the new bottlenecks that emerge with the cassava transformation, research and diffusion should be broadened beyond plant breeding and plant protection to include the following:

Country specific cassava transformation strategies are needed because the role of cassava varies significantly among African countries depending on the country's stage in the cassava transformation, cultural factors, agro-ecologies and market opportunities. This variation will determine whether cassava improvement strategies should emphasize one or more of the above-mentioned measures.

Table 9 identifies challenges for the six COSCA study countries that are consistent with the cassava sector development in each country. In both Ghana and Nigeria, the development of labour-saving mechanical harvesters and peelers will help make cassava more competitive with food grains in urban markets and with other plant starches that are used in livestock feed and as raw materials in industries. Also cassava varieties that can attain a maximum yield in less than twelve months will enable commercial farmers to grow cassava under continuous cultivation. To utilize the expanded production from the TMS varieties and improved agronomic practices, both Ghana and Nigeria need to more aggressively pursue new uses for cassava. International donor agencies should finance projects to develop new cassava food products and industrial uses such as preparing dried cassava roots malt for beer brewing, cassava syrup concentrate for soft drinks, small-scale cassava-based alcohol/ethanol production and manufacturing and utilizing cassava starch.

Table 9. Country specific challenges for cassava sector development

CountryPolicy ChallengesGenetic Research, Plant Protection, Agronomic Practices and TMS DiffusionFood Preparation and Processing
Nigeria-Research and development support for increasing the use of cassava in industry-Develop varieties that attain a maximum yield in less than 12 months-Develop labour-saving method for toasting gari
-Develop labour-saving technology for cassava harvesting-Diffuse the cassava leaves preparation method
Ghana-Research and development support for increasing the use of cassava in industry-Develop varieties that attain maximum yield in less than 12 months-Develop labour-saving method for toasting gari
-TMS multiplication and diffusion-Diffuse the cassava leaves preparation method
-Develop labour-saving technology for cassava harvesting
Uganda-Research and development support for increasing the use of cassava in industry-TMS multiplication and diffusion-Diffuse gari preparation methods
-Develop labour-saving technology for cassava harvesting-Diffuse mechanized grater technology
 -Diffuse the cassava leaves preparation method
Côte d'lvoire-Eliminate subsidies on imported rice and wheat-TMS multiplication and diffusion-Develop a grater that is suitable for attieke processing Diffuse the cassava leaves preparation method
-Develop labour-saving technology for cassava harvesting
Tanzania-Improve road access to urban market centres -Diffuse gari preparation methods
-Diffuse the mechanized grater technology
Congo-Improve civil stability -Diffuse gari preparation method
-Road access to urban market centres-Diffuse the mechanized grater technology
-Eliminate import subsidies on rice and wheat

Source: Nweke et al. 2001

In Uganda, research, government, NGOs and donor agencies are struggling with the devastating cassava mosaic disease by introducing the TMS varieties. TMS varieties are reported to be spreading and farmers are getting higher yields (World Bank, 2001). Government, NGOs and international donor agencies in Uganda should continue to address disease control. The diffusion of garb preparation methods and the mechanized grater should be promoted because they can reduce processing costs and expand the urban demand for cassava. NGOs and donor agencies should support a pilot project on using cassava as a raw material in beer malt, syrup concentrate for soft drinks and ethanol industries as well as development of the cassava starch as a raw material for other industries.

In Côte d'lvoire, the “market pull” of cassava can be increased by eliminating the subsidies on imported rice and wheat. A grater for making attieke needs to be developed to reduce the cost of a product which has a strong urban demand. In Tanzania, maize is the preferred staple and cassava is a famine-reserve crop. The diffusion of the gari preparation technology and the mechanized grater can help cassava compete in the urban market. International donor agencies should support pilot activities to find non-food uses for cassava. In the Congo, increasing market pull by improving roads and the removal of subsidies on imported rice and wheat will help cassava farmers tap new rural and urban markets.

The survey of industrial uses for cassava in Nigeria that was undertaken by COSCA researchers in early 2001 should be supplemented with an in-depth study of industrial uses for cassava in the major cassava producing countries in Africa.


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14 Waste was estimated to be 28 percent of the total cassava production in Africa from 1994 to 1998 (FAO 1999).

15 The countries are: Angola, the Central African Republic, the Congo, the People's Republic of Congo, Ghana, Mozambique and Nigeria.

16 The countries arc: the Republic of Benin, Cameroon, Côte d'lvoire, Guinea, Liberia, Madagascar, Sierra Leone, Tanzania, Togo, Uganda and Zambia.

17 The income elasticity of demand provides an insight into the level of market demand for a commodity. The income elasticity of demand measures the percent of change in the quantity of a commodity purchased (consumed) by consumers in response to one percent change in their incomes. A negative income elasticity of demand means that the quantity of the commodity purchased by consumers will decline with rising incomes. A zero percent income elasticity of demand means that the amount of the commodity demanded will be unchanged with rising incomes. An income elasticity of demand between zero and one percent implies that a one percent increase in incomes will cause consumers to increase the amount of the commodity they are willing to purchase although by less than one percent. Finally, an income elasticity of demand of more than one percent implies that market demand is very high for the commodity. Scholars and policy-makers who dismiss cassava as an inferior good assume that the income elasticity of demand for cassava is negative or zero.

18 In 1996 to 1998, there were 19.3 million cattle and 4.5 million pigs in Nigeria compared with 156 million cattle and 28 million pigs in Brazil (FAO, 2000). In Nigeria, nomadic herders move their cattle to wherever grass is available and tsetse is not a problem. The nomads neither respect boundaries nor do they pay for grazing rights. Frequently, they are halted by crop farmers, including cassava farmers, when cattle graze on fields with crops.

19 Cassava leaves are returned to the soil as organic matter. The cassava leaves are a good source of protein and vitamins and they are safe for human and animal consumption.

20 The physical soil properties assessed are clay, silt and sand content. The chemical properties are total nitrogen (Total N), organic matter (OM), available phosphorous (Available P), calcium (Ca), magnesium (Mg), potassium (K), sodium (Na) and manganese (Mn) contents; total exchangeable bases (TEB), total exchangeable acidity (TEA), effective cation exchange capacity (ECEC), base saturation and soil pH. For more details see Asadu and Nweke, 1999.

21 Several of the fields have been under continuous cultivation of cassava for a minimum of a decade.

22 Unpublished data from S. K. Hahn, IITA, lbadan.

23 The agro-ecological zones of these countries include humid forest (hereafter the forest) zone, forest-savannah transition (hereafter the transition zone) zone and the moist savannah (hereafter the savannah) zone. The forest zone is characterized by 9–12 months of growing season, more than 22°C daily mean temperature and less than 10°C temperature range. The transition zone is characterized by five to seven months of growing season, above 22°C daily mean temperature and above 10°C temperature range. The savannah zone is characterized by three or four months of growing season, above 22°C daily mean temperature and above 10°C temperature range (Carter and Jones, 1989).

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