1. A 21st century crop
The “food of the poor” has become a multipurpose crop that responds to the priorities of developing countries, to trends in the global economy and to the challenge of climate change.
Cassava (Manihot esculenta Crantz) is grown by smallholder farmers in more than 100 tropical and subtropical countries. Thanks to its efficient use of water and soil nutrients, and tolerance to drought and sporadic pest attacks, cassava can produce reasonable yields, using few if any inputs, in areas with poor soils and unpredictable rainfall.
The roots of cassava are very rich in carbohydrates, which makes them an important source of dietary energy. They can be consumed fresh after cooking, processed into food products, or fed to livestock. Cassava root starch can be used in a wide array of industries, from food manufacturing and pharmaceuticals to production of plywood, paper and bio-ethanol. In some countries, cassava is also grown for its leaves, which contain up to 25 percent protein.
Among the world’s staple food crops, cassava was long seen as the least suited to intensification. The Green Revolution approach to intensification – based on the use of genetically uniform crop varieties, intensive tillage, irrigation, fertilizer and pesticide – has proven inappropriate for cassava in rainfed areas.
But cassava’s importance has changed dramatically. FAO estimates the global harvest in 2012 at more than 280 million tonnes, a 60 percent increase since 2000. Global average yields have increased by almost 1.8 percent a year over the past decade, to 12.8 tonnes per hectare. With better crop and soil management, and higher yielding varieties more resistant to drought, pests and diseases, cassava could produce average root yields estimated at 23.2 tonnes.
Growth in cassava production is likely to accelerate over the current decade. Once seen as the “food of the poor”, cassava has emerged as a multipurpose crop for the 21st century – one that responds to developing countries’ priorities, to trends in the global economy and to the challenges of climate change. In brief:
- Rural development. Policymakers in tropical countries are recognizing the huge potential of cassava to spur rural industrial development and raise rural incomes.
- Urban food security. A major driver of production increases will be high cereal prices, which sparked global food price inflation in 2008.
- Import substitution. Domestically produced cassava flour can replace some of the wheat flour in bread.
- Renewable energy. Demand for cassava as a source of bio-ethanol is growing rapidly. Global output of bio-ethanol could reach 155 billion litres by 2020.
- New industrial uses. Cassava is second only to maize as a source of starch. Recent cassava mutations produce root starch that will be highly sought after by industry.
- Adaptation to climate change. Of the major staple crops in Africa, cassava is expected to be the least affected by climatic conditions predicted in 2030.
As market demand grows, cassava is likely to see a shift to increased monocropping on larger fields, the widespread adoption of higher-yielding genotypes, and higher rates of use of irrigation and agrochemicals. Intensive monocropping may simplify management and favour initially higher yields. Experience has shown, however, that it also increases the prevalence of pests and diseases, and accelerates the depletion of soil nutrient stocks.
In promoting programmes for intensified cassava production, policymakers should consider the lessons of quantum leap in global cereal production, decades of intensive cropping have depleted the natural resources of many agro-ecosystems, jeopardizing their future productivity, and added to the greenhouse gases responsible for climate change. Applying the same model to cassava production carries similar risks.
FAO’s ecosystem-based “Save and Grow” model of crop production intensification calls for “greening” the Green Revolution through farming practices that maintain healthy soil, cultivate a wider range of crop species and varieties in associations, rotations and sequences, use well-adapted, high-yielding varieties and good quality seed, manage water efficiently to obtain more crops per drop, and control pests through integrated pest management.
This brief shows how “Save and Grow” principles can be applied to cassava production intensification. With “Save and Grow”, developing countries can avoid the risks of unsustainable intensification, while realizing cassava’s potential for producing higher yields, alleviating hunger and rural poverty and contributing to national economic development.
Save and Grow: Cassava (FAO, 2013) can be purchased from [email protected]