ABSTRACT

Improving cultivation of cowpea in West Africa Alpha Y. Kamara, Lucky O. Omoigui and Nkeki Kamai, International Institute of Tropical Agriculture (IITA), Nigeria; Sylvester U. Ewansiha, University of Benin, Nigeria; and Hakeem A. Ajeigbe, International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), Nigeria

1 Introduction

2 Optimal plant population

3 Plant configuration in intercropping systems in West Africa

4 Manipulating planting dates to improve cowpea productivity

5 Nutrient management for increased cowpea productivity

6 Integrated pest management (IPM) in cowpea production

7 Future trends and conclusion

8 Where to look for further information

9 References

Cowpea [Vigna unguiculata (L.) Walp.] is a legume crop of vital importance to the livelihoods of millions of people in West and Central Africa (WCA). It provides a nutritious grain and a less expensive source of protein for both rural and urban poor consumers (Inaizumi et al., 1999). It can be grown and harvested in as little as 60-80 days. This enables households to harvest leaves and grains for consumption or sale during the ‘hungry season’ when grain reserves from the previous cereal harvests have been depleted and current crops are not ready for harvest. Most of the world’s cowpea (>90) is grown in sub-Saharan Africa, most of which is in West Africa particularly in Nigeria and Burkina Faso. Over 12.61 million ha are grown to cowpea worldwide, with an annual grain production of about 5.59 million tons (FAO, 2014). Of this amount, Africa accounts for 94% of grain production. Nigeria is the largest cowpea producer in the world and accounts for over 2.5 million tons grain production from an estimated 4.9 million ha (FAO, 2014). Other major producers in West Africa are Mali, Niger and Senegal. Cowpea cultivation is mainly under traditional systems and cowpea grain yields in farmers’ fields are low especially in the West African sub-region (0.025-0.3 t ha−1). This is caused by severe attacks of pest complexes, diseases, low soil fertility, drought, inadequate planting systems, inappropriate cultivars and lack of inputs (Ajeigbe et al., 2010a). In addition

to biotic and abiotic stresses, existing planting practices limit crop yields. Despite the availability of Striga and disease-resistant cowpea cultivars, grain yields on farmers’ fields are still low. However, on-station and researcher-managed plot yields are high and encouraging. Grain yields ranging from 0.5 to 2.76 t ha−1 have been reported in sole crop (Ajeigbe et al., 2005, 2008), whereas grain yields ranging from 0.37 to 1.27 t ha−1 have been reported in intercrop in the savannahs of Africa (Ajeigbe et al., 2005, 2010b). Yield potential assumes unconstrained crop growth and adequate management that avoids limitations from nutrient deficiencies; inadequate planting systems and water stress and reductions from weeds, pests and diseases (Evans and Fisher, 1999). Considering the large differences between farmers’ yields (0.3 t ha−1) and experimental station yields (1.5-2.5 t ha−1), potential for on-farm yield increase in the region is high. This has stimulated interest in agronomic practices that could enhance crop yields. Some of the agronomic practices that may increase cowpea productivity are optimal plant population, appropriate planting date, nutrient management, integrated pest management and suitable cropping system.