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.