Putting nitrogen to work for smallholder farmers

19 November, 2013 by (comments)

Many soils across Africa are starved of nitrogen, making it difficult for smallholder farmers to produce the yields needed to feed growing populations.

For many, the cost and accessibility, or lack thereof, puts nitrogen fertiliser beyond their reach. But what if they could harness free nitrogen from the atmosphere?


They can – by growing legumes, which ‘fix’ nitrogen into the soil. Biological nitrogen fixation (BNF) is the process by which certain plants, including legumes, harvest nitrogen from the atmosphere through a symbiosis with Rhizobium, a nitrogen fixing bacteria found naturally in soil, and subsequently put it into the ground, thereby improving soil health and the overall productivity of the farming system.

The question then is, how do you encourage farmers to grow these legumes?

Jeroen Huising, CIAT Scientist and N2Africa programme coordinator, said: “We learned long ago that technologies to improve the soil aren’t popular because, while improving soil fertility is important, it is not a high priority for smallholder farmers. They need better yields and higher incomes this year, not in five years’ time. What is needed is a technology that is profitable to the farmer, which improves soil fertility at the same time.”

Huising is one of a group of scientists who has been working to improve the BNF capabilities of legumes – along with supporting the creation of new markets to enable farmers to improve their incomes as well as their soil.

Increasing crop yields and soil health

N2Africa nodules

Since it began in 2009, N2Africa set out to boost the number of farmers cultivating improved nitrogen fixing legumes – specifically soybean, cowpea, groundnut and common bean. The first five-year phase recently came to an end, and researchers and partners met in Nairobi to evaluate the project and plan for the second phase – successfully granted funding by the Bill & Melinda Gates Foundation.

First, they developed the ‘technology’:

  • Identifying improved varieties of nitrogen fixing legumes
  • Developing rhizobium inoculum. While Rhizobium bacteria are found in soil, different legumes need specific strains to fix well. By adding the correct inoculum to legume seed before planting, farmers can further increase their yields.
  • Adding phosphorus fertiliser
  • Improving crop management practices

Then they shared it with farmers.

The results are pretty impressive. The project has reached more than 250,000 smallholder farmers across eight countries with better genotypes of legumes and rhizobia inoculants. There is proof that using the full technology (improved varieties and inoculum, along with the addition of phosphorus fertiliser and improved crop management practices), can more than double legume yields AND improve the performance of successive crops by as much as 50 per cent as a result of higher nitrogen levels in the soil.

Success in market development is smaller but still impressive. N2Africa has helped more than 10,000 farmers in western Kenya access niche soybean markets, which have the potential to grow significantly. The demand from the processing industry leads to the import of over 8 million tons of soybeans annually from Uganda, Rwanda, DRC and other countries; a gap in the market that Kenyan farmers could feasibly fill.

So what’s the catch? Well, there are some questions that still need to be answered – and these are on the cards for phase two.

Firstly, the response of legumes to inoculants and fertiliser varies considerably, meaning that even with full adoption, yield increases are not the same. Scientists need to find out why this is.

N2Africa Ghana

Secondly, while many farmers are using improved varieties and, some, inoculants (and are often rewarded with increased yields), most don’t adopt the full technology, and so don’t benefit from its full potential. The question for phase two is how to improve the availability of improved seed and inoculants, and how to ramp up the number of farmers who use them in conjunction with phosphorus fertiliser and improved crop management practices.

Developing markets

If we want smallholder farmers in Africa to adopt technologies that improve soil and farm productivity, then we also need to support them to exploit market opportunities and improve their incomes. Yet, lack of access to markets means many farmers struggle every season to sell their goods.

Perhaps the best examples of how N2Africa has supported market development are from western Kenya, where soybean farmers are being linked 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.

Kenyan farmers also 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.

Right now, they’re making small potatoes compared to the potential. But, it’s a positive start that is already making a difference.

N2Africa isn’t going to set the world alight – just yet. But, with more research, it shows a lot of potential. Let’s see what the next five years bring.


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 & Melinda Gates Foundation and the Howard G. Buffet Foundation.

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.

For more information visit www.n2africa.org/ or visit www.n2africa.tv/ to watch films of N2Africa in action.

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