New soil fertility method boosts crop production

A maize farmer: The new method of improving soil fertility has boosted soya bean and maize yields. Photo/FILE
A maize farmer: The new method of improving soil fertility has boosted soya bean and maize yields. Photo/FILE 

An innovative method of boosting soil fertility has increased yields for farmers in Western Kenya by up to 10 times, promising to increase harvests and boost nutrition if adopted on wide scale.

The four-year project, which was launched last year, has raised the net returns for farmers who adopted the legume and rhizobial inoculant technologies.

Launched in Kenya and seven other African countries to triple the take-up of free atmospheric nitrogen through Biological Nitrogen Fixation, the project has delivered near-instant benefits through improved crop and livestock productivity, nutrition, farm income and soil health.

It has also sparked a revolution in legume processing, specifically of soya, in Western Kenya.

Expected benefits

The project’s total benefits at the end of the four years are projected to be at least $31.9 million based on estimates of the increased productivity of the targeted grain legumes— which include soya-bean, common beans, cowpeas, groundnuts, chickpeas and pigeon peas — and through their contribution to the yield of subsequent maize crops.

However, in Western Kenya where around 20,000 smallholder farmers from more than 10 districts were targeted, they have already increased their net returns from soya-bean cultivation from four to 14 times.

The initiative has also led to the creation of several soya-bean resource centres in Western Province, with many farm families now easily accessing soya-milk, and farmers widely adopting soya-milk processing machines.

Agriculture experts say the legume crops often fail to fix useful amounts of nitrogen in the soil in Africa because partner bacteria are not present, or because the soil lacks other nutrients, such as phosphorous.

But the new technology now allows farmers to introduce the bacteria as inoculants, together with the seed and small amounts of other nutrients.

This simple package increases farmers’ yields while improving the soil’s fertility.

“Agricultural production in most parts of sub-Saharan Africa is dominated by smallholder farming systems, which are associated with low productivity. Although the inclusion of legumes has the potential to improve system productivity, often less than five to 10 per cent of cultivated land is currently planted with field legumes.

Grain legumes are often included as minor intercrops in fields of cereals and other staple crops.

This is because smallholder farmers operate under diverse socio-ecological constraints that limit the productivity of legumes and farmers ability to scale up the integration of legumes into their farming systems,” said Wycliffe Oparanya, Minister of State for Planning, National Development and Vision 2030 during the launch of the Biological Nitrogen Fixation project last year.

Despite an Africa Union resolution in 2006 when leaders endorsed efforts to improve fertiliser access for small-scale farmers, by promoting locally-adapted manufacturing and establishing financing mechanisms for procurement, smallholders are still struggling to access the input.

Fix naturally

Agro-experts have therefore become aggressive in pushing biological nitrogen fixation, which is sometimes free and is easy to learn, as the best route to follow for Africa.

The process involves crop rotation, with the planting of legumes helping to fix nitrogen naturally.

According to Kenya Agricultural Research Institute, the country faces an enormous soil fertility problem, with research showing that in Western and Central provinces, 7.5 million hectares of land are highly acidic, a problem shared by large parts of Ethiopia, Rwanda, Uganda and Zambia.

The high acidity is due to the leaching of nutrients by the abundant rains, continuous cultivation and misapplication of nitrogen fertilisers.

However, in Brazil and South Africa, agricultural scientists have manipulated the symbiotic relationship between the growth of legumes.