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Isotopic Technique Helps Benin Farmers Triple Yields and Improve Livelihoods


Soybean farmer Leonard Djegui from central Benin has tripled his income following the introduction of intercropping and the optimization of fertilizer levels. Experiments using an isotopic technique enabled researchers to help him introduce these new farming practices (Photo: M. Gaspar/IAEA)

Attinkpaye, Dassa-Zoume, Benin -- Soybean farmer Leonard Djegui never had the chance to go to school but he has learned two facts about nuclear science in recent years: atoms make up the soil and they have helped triple his income, allowing him to build a new house and send his children to university.

Djegui is not alone: around 14 000 farmers in central and northern Benin have achieved significant yield increases for both maize and legume crops such as soybean – providing more food for their families and much higher incomes than they could even dream of a few years ago.

"I did not go to school, but I do understand that science is important," Djegui said proudly showing his new house, made of bricks, replacing his previous mud hut. "It allows my maize and soya to grow taller and provides for a much richer harvest."

Leonard Djegui is examining his new house, currently under construction. Extra farming income thanks to the introdution of experiments conducted using isotopic techniques has enabled him to replace his mud hut. (Photo: M. Gaspar/IAEA) 

The secret: the use of isotopic and nuclear derived techniques to measure and properly increase the amount of nitrogen – necessary for plant growth – the crops take up (see Nitrogen uptake from the air). Legumes such as soybean and peanuts are able to take up nitrogen from the air, which they then deposit in the soil, making it more fertile also for the maize crop that farmers plant in the next season, explained Pascal Houngnandan, Vice President of the National University of Agriculture and Director of Soil Microbiology at the University of Abomey-Calavi, the country’s main research institution just outside the capital Cotonou. This intercropping of maize and legumes results in an increase in the yields of both crops. Depending on the soil type, it also means no or little commercial fertilizer is required, saving farmers the additional expense.

The IAEA, in cooperation with the Food and Agriculture Organization of the United Nations (FAO), has supported the project by providing expert advice and helping Houngnandan and his team interpret the data. The IAEA, through its technical cooperation programme, has also provided much needed equipment and training that allow the researchers not only to conduct the experiments, but to also produce the bacteria required for the legumes to take up even more nitrogen from the air.

Scientists in 70 countries benefit from such assistance, including support to customize the method to their particular crops and soil types, said Joseph Adu-Gyamfi, soil fertility management specialist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture.

Mixing seeds and bacteria

On this late June afternoon, at the beginning of the planting season, Djegui and his neighbours were busy mixing the bacteria received from the lab with soybean seeds that were to be planted in the following weeks. Meanwhile, other workers from this village of 1000 were clearing weeds from surrounding land that used to lay bare, so that more soybean can be grown.

Albert Ahotondji, one of Djegui’s neighbours, is now growing soybean on 6 hectares of his land, up from 2 hectares two years ago. Previously he did not have the cash to buy seeds and fertilizer for all of his land, and was forced to leave some of it unused. He now has enough cash to till his entire land and can also put money aside for when his children will go to university. “I will be able to afford to rent a room for them in the city,” he said proudly.

It is the fourth consecutive season the smallholder farmers of this village are making use of the bacteria they buy from the university through extension workers, who also showed them how to improve their farming practices.

There are 100 000 soy farmers around Benin, and the use of the new technique is spreading fast, said Fortuné Amonsou Biaou, Executive Director of the National Union of Soybean Producers of Benin. Seeing yields triple or even quadruple is very common, he said. Depending on the region, farmers used to harvest between 500 and 800 kilograms of soybean per hectare. This has now increased to between 1.2 and 2 tons. This is particularly important in this primarily agricultural country, where over half of the population is engaged in farming, which makes up 40% of the economy.

Soybean is used to make vegetable oil and animal fodder, and is also a major export crop on regional markets. “By also increasing maize yields, we increase food security for the rural population, while the higher soybean production increases their disposable income,” Amonsou Biaou said.

Félix Kouelo Alladassi, Assistant Professor in Soil and Water Conservation at the University of Abomey-Calavi, preparing soybean plants for an experiment using isotopic techniques. (Photo: M. Gaspar/IAEA)

Houngnandan founded the laboratory in 2002 to research the impact of intercropping on yields. Experiments with the use of isotopic techniques and the inoculants began a few years later, and field experiments followed in 2008. A few farmers started to use the technique as part of a pilot project in 2011, while its large scale use began in 2013, when the growers association and local agricultural authorities joined in to promote it. During the 2016-2017 growing season, the laboratory produced 16 000 bags of the inoculant bacteria in the form of biofertilizers.

"It has taken us a while to scale up, but the results are very clear now," said Houngnandan while demonstrating the use of the equipment he has received from the IAEA. "I hope that in a few years every single farmer will use it."

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