From: Joris Tielens, SciDevNet, More from this Affiliate
Published November 5, 2013 08:59 AM

Nitrogen fixation helps double some African farm yields

A large-scale research and development project has shown that giving farmers resources and advice on nitrogen fixation through legume plants can double yields and boost incomes in Africa.

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But not all farmers are benefiting from this practice due to a lack of access to inputs, such as fertilizers says Ken Giller, the leader of the N2Africa project, as a second phase to widen access to the initiative is announced with US$25.3 million funding from the Bill & Melinda Gates Foundation for the next five years.

Researchers and representatives of NGOs and companies gathered in Nairobi, Kenya, yesterday to discuss the results of N2Africa's first phase.

This was carried out by a partnership comprising Wageningen University in the Netherlands, the International Centre for Tropical Agriculture, the International Institute of Tropical Agriculture and several NGOs, universities and research centers, mostly based in Africa.

Through the project, around 252,000 smallholders in eight African countries were given legumes, such as soybeans, groundnuts or beans.

Such plants host soil bacteria called rhizobia in their roots that fix atmospheric nitrogen, which is important for plant growth, into the soil. These nitrogen-fixing bacteria can be added to the soil by applying an inoculant, a mixture of peat and rhizobia bacteria.

As well as receiving new legume varieties farmers were advised to use improved inoculants, special fertilizers with more phosphate and were given advice on crop rotation and intercropping.

"We have measurements and observations on thousands of farmers' fields across Africa," says Giller, who is a plant scientist at Wageningen University.

Results from an early impact study presented at today's meeting in Nairobi show that crop yields could double using the new legumes, inoculant and fertilizer.

But average yields increased only between 78 and 272 kilograms per hectare for different crops, whereas scientists hoped for a target increase of 954 kilograms per hectare.

The average increase in household income was US$335 a year instead of the hoped-for US$465 goal.

"We've got proof of massive improvements in yield at field level, due to the right combination of better varieties of legumes and rhizobia, adapted fertilizer and improved management," Giller says. "Yet many farmers can't access the right inputs like inoculants and fertilizers, or sow the crops at the ideal time, and that causes lower yields."

The special fertilizer is often not available or is too expensive for farmers, he says. And, while inoculants are relatively cheap, they are not available everywhere.

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African farm image via Shutterstock.

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