A pan-African project aimed at improving legume technologies to counter the debilitating impact of low-nitrogen soils on agricultural production is generating higher yields and new income streams for smallholder farmers.

Since it began in 2009, N2Africa set out to increase the adoption of improved nitrogen fixing legumes - specifically soybean, cowpea, groundnut and common bean - and support the creation of new markets for the resulting crops so that farmers continue to improve the quality of their soil, as well as improve household income and nutrition.

To date, the project has reached more than 250,000 smallholder farmers across eight countries with better genotypes of legumes and rhizobia inoculants. These, in addition to phosphorus fertiliser and improved crop management practices, more than doubled legume yields in many cases. They can also improve performance of successive crops by as much as 50 per cent as a result of improved soil nitrogen levels. Net household income rose by an estimated average of $355 per year.

In Kenya, N2Africa has helped more than 10,000 farmers access niche soybean markets, which have the potential to grow significantly. The demand from the processing industry alone leads to the import of over 8 million tons of soybeans annually from Uganda, Rwanda, DRC and other countries.

N2Africa is a collaborative project led by Wageningen University with the International Institute of Tropical Agriculture (IITA) and the International Centre for Tropical Agriculture (CIAT), and funded by the Bill and Melinda Gates Foundation and the Howard G. Buffet Foundation. The first phase of N2Africa ends this year and the Bill and Melinda Gates Foundation recently approved phase two of the project.

The project started at the end of 2009 in Ghana, Democratic Republic of Congo, Ghana, Kenya, Malawi, Mozambique, Nigeria, Rwanda and Zimbabwe. Liberia and Sierra Leone were added two years later, with funding from the Howard G. Buffet Foundation. This year activities started in Ethiopia, Tanzania and Uganda.

Increasing crop yields and soil health
Many soils in Africa are severely depleted of nitrogen, making it difficult for smallholder farmers to produce the yields needed to feed growing populations.

Yet, according to Bernard Vanlauwe, R4D Director of IITA, "smallholder farmers often cannot access or afford the inputs needed to put nitrogen back into the ground. Biological nitrogen fixation (BNF) can help them do this - and earn them additional income at the same time."

Nitrogen fixation is the process by which certain plants, including legumes, take nitrogen gas from the atmosphere, incorporate it into their tissue, and subsequently into the ground, improving soil health and the overall productivity of the farming system.

In addition, N2Africa demonstrated that farmers could significantly increase their legume yields by combining improved varieties with rhizobium inoculants, phosphorus fertiliser and accompanying agronomic management practices.

Rhizobium bacteria are found in soil, and are responsible for fixing nitrogen but different legumes need specific rhizobium strains to fix well. By adding the correct inoculum to legume seed before planting, farmers can further increase their yields.

Professor Ken Giller, N2Africa Director, said: "There have been very few projects that have been able to test technologies at the scale that we've been able to. We have measurements and observations on thousands of farmers' fields across Africa. With these we can understand what the reasons are for better or poor crop performance, and what particular technology fits each type of farmer. Legumes are very flexible crops, and suitable for both the wealthier or poorest farmers."

"We've got proof of massive improvements in yield at field level, due to the right combination of better genotypes of legumes and rhizobia, adapted fertiliser and improved crop management."

Developing markets
Lack of access to markets means many smallholder farmers in Africa struggle every season to sell their goods. N2Africa technologies are helping Kenyan farmers exploit gaps in the local and national soybean markets.

In western Kenya, N2Africa linked soybean farmers with lucrative commercial and non-profit markets:?

Food manufacturer, Promasidor, set up 16 soybean grain collection points to buy Kenyan soybeans for Sossi, a soybean product available in Kenyan supermarkets. In 2012, Promasidor bought 160 tons of soybean from Kenyan farmers.

N2Africa farmers supply 220 tons of soybean each year to three soybean processing factories set up by UNIDO and the Government of Japan to provide soy products for school feeding programmes and emergency relief.

On a local scale, N2Africa has supported farmers to set up their own soybean processing plants, including mincer, soaking basin, filters, press plates and pasteurizing pans. Women use them in late afternoons to mince soybeans for their evening meals.

Jeroen Huising, CIAT Scientist and N2Africa programme coordinator, said: "In contrast to staple crops, like maize and rice, legumes fetch a higher price. But we need to support farmers to have access to these markets. Once we do that, the technology has the potential to be self-sustaining - enabling farmers to increase the nitrogen in their soils, attain higher yields and earn more money through crop sales."