New method to boost cowpea crop yields

Caroline Kisera tends to her cow peas vegetables her Oyugis farm. [Sammy Omingo, Standard]

Researchers at the International Institute for Tropical Agriculture (IITA) have developed a simple method for increasing cowpea yield and protein content of seeds.

Cowpea is an important crop in drier parts of the world and provide proteins for millions of people. Cowpeas account for roughly 16 per cent of Kenya's pulse production and 90 per cent of the production is grown in Eastern Kenya, mainly in Kitui, Machakos, Makueni, Embu, and Tharaka-Nithi counties.

The legume is an important source of protein and calories, as well as vitamins and key minerals such as zinc and iron. However, researchers note that yields per unit areas and its protein content must be increased to meet the protein demands.

IITA researchers based in West Africa observed that plant density and top-dressing with fertiliser have a huge impact on overall yield and protein content. During the investigation, three planting density plots-normal, high, and super high-were established in the different regions. The regions were characterised by their annual rainfall. The north region was semi-arid with an annual rainfall of 520 mm, the central region was semi-arid with an annual rainfall of 780 mm, and the south region was sub-humid with an annual rainfall of 1175 mm. The result showed that high-density planting and top-dressing during flowering could increase the yield and grain protein content of cowpea in different agroecological zones across different regions.

Under such approaches, the yield significantly increased by as much as 214.5 per cent, with an average value of 88.9 per cent. Applying top-dressing when the plants started flowering increased the seed protein content by up to 24.4 per cent. The findings suggested that the cowpea yield can be easily improved, even when farmers have no access to fertiliser.

Even if the cowpea yields for any individual farmers do not improve dramatically, the effects of high- and super high-density planting could greatly impact national or regional production. The researchers advised farmers to evaluate the soil type, soil fertility, and varieties of cowpea they use in their locations to adapt to the developed techniques.

"Our findings could contribute to achieving stable and sustainable food production," said Dr Haruki Ishikawa, lead researcher in the study.

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