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Tripling Cassava Yields with the Help of Nuclear Science: IAEA Commemorates World Day to Combat Desertification and Drought


Farmers in the Gitega Province in central Burundi harvest cassava, a starchy root vegetable and major cash crop, after using nuclear-enhanced methods to boost crop yields. (Photo: E. Vyizigiro/Institute of Agricultural Science of Burundi).

Seeing is believing, and when neighbouring farmers visit Theogene Ntakarutimana’s cassava farm in central Burundi, on what is increasingly arid terrain, they are often speechless.

“Everyone who visits my farm and sees the way I am farming and producing cassava, they get excited,” said Ntakarutimana, who started growing cassava using methods enhanced with nuclear science and related techniques in 2016. “I used to have a low yield, about 11 tonnes per hectare, but thanks to the enhanced practices, production has increased to 30, sometimes 33 tonnes. Other farmers are asking about the methods I have applied, and everyone is willing to learn.”

Cassava, a starchy root vegetable, is the third largest source of carbohydrates worldwide, after rice and maize and a major cash crop for many farmers in Africa. The continent produces around 55% of the world’s output, followed by Asia with around 34%. However, in many parts of Asia and Africa, harsh conditions, including drought and water scarcity, and declining soil fertility, are affecting traditional cassava farms and threatening food security.

In 2016, the IAEA, in cooperation with the Food and Agriculture Organization of the United Nations (FAO), partnered with research institutes and farmer associations to boost cassava production by developing improved soil nutrient and water management practices using nuclear-derived techniques. The new practices developed through the project have led to an up to three-fold increase in cassava yields.

Nuclear applications to guide best practices

In the first phase of the project, researchers in Burundi, Central African Republic and Laos were trained to use nitrogen-15 (15N), a stable isotope of nitrogen, to measure plant uptake of added nitrogen fertilizer and to track the amount of nitrogen absorbed. Nitrogen is one of the primary nutrients that plants need for optimal growth, and the amount of nitrogen found in soil will depend on soil fertility and quality. Nitrogen, in combination with potassium and phosphorous, is used as a fertilizer to enhance cassava growth.

“Nitrogen is part of all life — the air we breathe, the water we drink, the food we eat,” said Mohammad Zaman, a soil scientist in the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. “Using nitrogen-15 does not solve the problem, but it gives you the ability to know how to better manage nitrogen.”

By quantifying the amount of nitrogen plants acquire, local researchers determined the precise amount of fertilizer farmers should use and at which stage of the plant life cycle and how to incorporate locally available manure as an added nutrient. They also used isotopic techniques to determine how much water cassava needs to thrive to minimize water waste, and learned about integrated pest management, timely harvesting and how to incorporate other conventional farming techniques, such as building up soil fertility, to further boost yields.

Cassava production demonstration field in Cibitoke Province in northwest Burundi. (Photo: E. Vyizigiro/ISABU)

Scientists and farmers working together

In the second phase of the project, training courses were organized for local researchers and organizers to develop region-specific practices using nuclear science. Subsequent training courses with classroom activities and hands-on field work were also organized for more than 350 farmers, including 146 women farmers.

“We involved farmers from the beginning,” said Ernest Vyizigiro of the Institute of Agricultural Science of Burundi (ISABU), whose team worked with two regional farmer associations to introduce best practices to about 80 farmers in Burundi. “We conducted several training courses and hosted a farmer field day, where we took farmers to the research center and demonstration plots.”

In a field demonstration in 2016, Vyizigiro and his team exhibited for farmers three different cassava plots farmed using traditional methods, ISABU best practices and the nuclear science-enhanced techniques. The traditional approach produced under 12 tonnes and the ISABU’s about 25 tonnes, while the nuclear-derived techniques yielded 33 tonnes.  

Similar results were reported in Laos in November 2018 by the National Agricultural and Forestry Research Institute (NAFRI). Their first demonstration plot using the nuclear-backed methods showed increased cassava yields from 16 tonnes to up to 37 tonnes.

Despite seeing the results for themselves, some farmers were initially hesitant to apply new methods to their traditional practices, said Siviengkhek Phommalath of Laos’s Agricultural Research Center, but interest is slowly growing as news of demonstration plots have spread by word of mouth and attracted more curious farmers. Phommalath explained how at least eight farmers visit the demonstration plot at least twice a month.

“We encourage farmers to be part of demonstration plots, so that they are involved from the very beginning, and they can see the benefits for themselves,” Phommalath said.

Disseminating the fruits of science

To reach more farmers and further spread best practices, the IAEA continues to work with counterparts in Africa and Asia to develop an easy-to-use brochure for farmers. “It is a complete package right from the beginning until harvest,” Zaman said. “The brochure is a tool box that shows farmers what to do, from preparing the land to applying fertilizer, weed management, insect management and, lastly, a timely harvest.” The brochure will be translated into local languages and distributed before the end of this year.

As a result of growing interest from other countries following the successes in the three initial countries, the IAEA plans to launch a regional technical cooperation project in 2020 to develop and disseminate best practices for cassava production in West, Central and East Africa.

2nd International Seminar on Drought and Agriculture

In commemoration of the World Day to Combat Desertification and Drought, the FAO, in collaboration with the Government of the Netherlands, is organizing the 2nd International Seminar on Drought and Agriculture on 17 June in Rome. The seminar, which will be livestreamed, will present tools and best practices to be better prepared and resilient to drought. Projects like this, supported by the Joint FAO/IAEA Division, are part of the commemoration and celebration of the event.

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