One of the most important food security crops in Africa is cassava, a root vegetable eaten by around half a billion people every day.
Africa produces nearly 200 million tonnes of cassava every year, around 60 per cent of the world’s total production. However, due to climate change, water scarcity and declining soil fertility, cassava yields are being adversely affected across the continent, causing many people to face food shortages and malnutrition.
Experts from the IAEA and the Food and Agriculture Organization of the United Nations (FAO) are working to help African farmers mitigate these effects of climate change by sharing sustainable and efficient nutrient, water and soil management practices.
“Thanks to the knowledge we’ve gained here about climate-smart agricultural practices, we are now more informed and better equipped about cassava production and hope to use this knowledge to improve our yields,” said Misses Unu, a farmer from Nigeria, as he sat on the field after the harvest, looking at the piles of large cassava roots.
He and many other local farmers in over a dozen African countries participated in field demonstration trials run by the joint IAEA/FAO Centre in the IAEA’s Department of Nuclear Science and Applications. This was aimed at training them to grow more and better-quality cassava using nuclear and related climate-smart agricultural techniques. The trials were conducted from 2021 to 2023 and continue to take place in a number of countries.
Cassava is a starchy root vegetable that looks like a sweet potato. It is the third most important source of calories in the tropics after rice and maize. First brought to Africa by Portuguese merchants from Brazil in the 16th century, over the years it has become the continent’s most produced cash crop, deeply embedded in local cuisine. Literally, every part of this crop can be used. While the leaves are rich in protein, the root can be boiled, steamed, fried, cut into chips or turned into starch, flour or animal feed. Cassava is also relatively easy to grow as it adapts well to harsh environmental conditions, including high temperatures and drought. Due to its hardiness, farmers often think there is no need to apply nutrient and water to grow cassava, but after a few years, this leads to nutrient-mining and low crop productivity.
To enhance food security and increase the incomes of cassava farmers, the IAEA launched a technical cooperation project in 2020 in collaboration with local research institutes and farmer associations in Africa. Farmers in several African countries were able to double and even triple their cassava yields by applying nutrient, water and soil management practices, developed by experts from the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture.
Nuclear science gives clues to best farming practices
As part of the project, researchers and farmers in Africa were trained in the application of nuclear techniques for cassava production. For healthy plant formation, growth, photosynthesis and metabolism, cassava requires 17 essential nutrients, particularly nitrogen, potassium and phosphorus in a specific ratio.
Deficiencies in these nutrients in the soil result in poor yields, while excessive application of fertilizers containing these nutrients can pollute surface and ground water and increase emissions of greenhouse gases. Isotopic techniques can help assess plant uptake of added fertilizers and track their movement in the soil, plant, water and atmosphere.
“Nuclear science helps us better understand the exact amount of nutrients cassava needs and helps farmers apply fertilizers in the most effective way at the right stage of the plant’s life cycle,” said Mohammad Zaman, a soil scientist at the Joint FAO/IAEA Centre.
The training provided through the IAEA technical cooperation programme also included isotopic techniques using Nitrogen-15 (15N) to measure the efficiency of fertilizer use and cosmic ray neutron sensors, which help determine precisely how much nutrients and water cassava needs to thrive. “The data collected through these methods can guide farmers on how to apply nutrients and water more efficiently to minimize their wastage,” added Zaman.
A farmer’s guide to climate-smart agriculture
A farmer in Central Africa Republic is transporting cassava tubers after harvest. (Photo: M. Zaman/IAEA)
By applying climate-smart agricultural practices, cassava yields can be significantly improved. For example, around 13 per cent of improvement in yields comes from planting clean and healthy rooted cuttings, 17 per cent comes from enhancing soil fertility and 16 per cent comes from controlling insect pests and diseases.
To help farmers achieve better results, experts from the Joint FAO/IAEA Centre of Nuclear Techniques in Food and Agriculture prepared step-by-step production guidelines which include information on selecting improved cassava varieties, preparing planting materials, managing soil and water resources, applying fertilizers and nutrients, controlling insects, pests and diseases, as well as harvesting and postharvest processing.
Subsequently, several training sessions on the application of these methods and on-farm trials were organised for farmers in Burundi, the Central African Republic, Ghana, Nigeria and Rwanda.
In Ghana, cassava is the most important staple crop. Its production contributes about 22 per cent of agricultural GDP and employs over 70 per cent of all farmers, making the country one of the top five cassava producers in Africa. The vegetable is traditionally cultivated by smallholder farmers, who use it to prepare a variety of traditional cassava dishes, including fufu, cassava dough, or banku, a mixture of cassava and corn doughs.
The average yield in Ghana is 14 to 21 tonnes per hectare. Through the technical cooperation project, the application of climate-smart agricultural practices recommended by the Joint IAEA and FAO Centre of Nuclear Techniques in Food and Agriculture helped more than triple the yields, depending on the farming site, the variety and the amount of organic and chemical fertilizers applied. Field demonstration trials showed an increase from around 20 tonnes per hectare to over 70 tonnes.
Similar, and even higher results were observed in other countries. In Burundi, where conventional farming yields around 12 tonnes per hectare, nuclear-based methods helped to reap over 37 tonnes. In Rwanda, the use of climate-smart agriculture increased yields from less than 15 tonnes to almost 62 tonnes. In the Central African Republic, the field trials made it possible to harvest around 50 tonnes, compared with an average of 10 tonnes.
Cassava helps generate income, create jobs and guarantee food security for millions of Africans. “The IAEA will continue to help countries in applying nuclear science-enhanced farming techniques for growing cassava to strengthen economies, spur development and reinforce food security on the African continent,” Shaukat Abdulrazak, Director of the IAEA’s Technical Cooperation Division for Africa said.
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