Cassava

Cassava (Manihot esculenta Crantz) is grown in over 90 countries and is the third most important source of calories in the tropics, after rice and maize. It is a staple for half a billion people in Africa, Asia, and Latin America. It is grown by poor farmers, many of them women, often on marginal land. For these people and their families, cassava is vital for both food security and income generation. Cassava is also a source of commercial animal feed, fiber for paper and textile manufacturers, and starch for food and pharmaceutical industries.

Cassava production in Colombia's southwestern Cauca department (Photo: Neil Palmer/CIAT)
Cassava production in Colombia's southwestern Cauca department (Photo: Neil Palmer/CIAT)

Origin and uses

Cassava originated in tropical America and was first introduced into Africa in the Congo basin by the Portuguese around 1558.

The Democratic Republic of Congo is the largest consumer of cassava in Africa, followed by Nigeria. Usually, cassava is primarily used as food, except in Thailand where 90% of the cassava produced is exported and the rest used in industry. In Africa, about 90% is used as food. In Asia, over half is used as food, and exports account for 27% of production, primarily from Thailand and Indonesia. In Latin America and the Caribbean, cassava is used mainly as food (42%) and feed (33%). The use of cassava in industry accounts for 10% of production in the Americas, 9% in Asia, and 0.1% in Africa.

Production

Global production of cassava has nearly doubled over the past 30 years to about 230 million metric tons in 2010. Over half is grown in Africa, with a third in Asia and 14% in Latin America. Nigeria is the largest producer, growing 38 million metric tons in 2010. Other major producers are Brazil, Indonesia, Thailand, and the Democratic Republic of Congo.

Nutrition

Cassava is rich in carbohydrates, calcium, vitamins B and C, and essential minerals. Cassava leaves are rich in protein (around 7%). However, nutrient composition differs according to the variety, the age of the harvested crop, and soil conditions and climate during cultivation. Much of the protein and vitamin content is lost when food products are prepared. Cassava biofortified with vitamin A has been released in several countries, including the Democratic Republic of Congo and Nigeria.

Impact of CGIAR Centers

By the late 1990s, about 10 to 15 million rural households had benefited from improved cassava varieties that were planted to about 7% of the total area in Latin America and the Caribbean, 18% in Africa, and 23% in Asia. The yield increases ranged from 20% to 130%. The gross economic value generated by improved cassava was estimated at almost US$440 million as far back as 1998, with an internal rate of return of 9% to 22%.

According to more recent estimates, in Thailand and Vietnam adoption of improved varieties has reached nearly 90% and has generated gains worth US$12 billion over the last 2 decades.

The impact of cassava research in Southeast Asia was made possible by extraordinary changes in its role. Having served for centuries as a secondary food crop, from the 1970s cassava became a preferred raw material for the production of animal feed and of starch for a wide variety of industrial uses. The cash that farmers are now pocketing as a result creates benefits that are evident in small rural communities across the region.

In the late 1980s, Africa witnessed one of the CGIAR’s most spectacular research achievements since the Green Revolution: the biological control of two devastating insect pests of cassava. The International Institute of Tropical Agriculture’s (IITA) biological control program, in collaboration with African research services, resulted in a 95% reduction in cassava mealybug damage and a 50% reduction in damage caused by the cassava green mite. The economic returns — reaching a current value of US$9 billion on research on just cassava mealybug — far exceed the CGIAR’s total investment in Africa since 1971.

The cumulative value of the increased production derived from new cassava varieties was estimated in 1990 at more than US$432 million in Asia and US$81 million in Latin America and the Caribbean. The internal rate of return to cassava improvement at the International Center for Tropical Agriculture (CIAT) is estimated at 12% for Latin America and 75% for Asia. In addition to enhanced productivity, the nutritional quality of cassava and other quality traits have been improved over the last decade. Therefore, in addition to higher productivity, the value of the harvest is also being improved.

In Africa, IITA scientists have played a leading role in developing improved cassava varieties that give sustainable yields of about 50% more than local varieties. Distribution of varieties resistant to cassava mosaic disease in response to the outbreak in East and Central Africa resulted in production levels recovering to pre-epidemic levels in less than five years.

During the past three decades, IITA has trained more than 9000 researchers and technicians in ten African countries in processing high-quality cassava flour. As a result, the private sector in Madagascar, Nigeria, Tanzania, and Uganda has begun using the flour as a raw material for products such as biscuits and noodles.

Sources and more information