Cultivation of Cowpea Challenges in West Africa for Food Security: Analysis of Factors Driving Yield Gap in Benin

Abstract

Feeding the world in 2050 requires us to find ways to boost yields of the main local crops. Among those crops, cowpea is one of the grain legumes that is playing an important role in the livelihood of millions of people in West Africa, especially in Benin. Unfortunately, cowpea on-farm yields are very low. In order to understand the main factors explaining cowpea yield gaps, we collected and analyzed detailed survey data from 298 cowpea fields in Benin during the 2017, 2018 and 2019′s rainy seasons, respectively. Composite soil samples were collected from cowpea fields and analyzed in the laboratory. Data on farm field management practices and field conditions were recorded through interviews with 606 farmers. Average cowpea grain yields were low and seldom surpassed 700 kg ha−1 on farmer’s fields. Significant differences were observed between cowpea grain yields from northern to southern Benin (p < 0.05), and the lowest yields were observed in northern Benin. These low yields are related to crop management practices, soil nutrient contents, and the interaction of both. According to the model of regression tree from northern to southern Benin, the use of mineral fertilizer, insecticide sprays to control pests, and the improvement of phosphorus, nitrogen, potassium (P, N, K) and cation sum content in the topsoil would increase cowpea grain yields. Insect pests, diseases, and soil fertility decline are the largest constraints limiting grain yield in Benin. Future research should focus on formulating site-specific fertilizer recommendations for effective cowpea cultivation in Benin, as well as the control of insect pests and diseases.

Cowpea Growth and Nitrogen Fixation Performance under Different Mulch Treatments

“…In the study of Munjonji, Ayisi [11], a biomass yield of more than 2 t/ha was reported for cowpea under water stress conditions. The 2017 grain yield levels were lower but were in the range of what is obtainable and reported under rainfed conditions in many smallholder farming sectors [9]. Despite the low yields, mulching showed that it has a potential to increase the biomass and grain yield of cowpea.…”

“…Cowpea (Vigna unguiculata (L.) Walp) is an important protein-rich food consumed by rural and urban communities of Africa and other countries [8]. Most of the cowpea is produced by smallholder farmers who are resource poor and farm on marginal soils [9]. Thus, it is critical for these farmers who cannot afford inorganic fertilisers or manures to maximise on biologically fixed nitrogen and the retention of high-quality organic residues in their soils.…”

Legume seed system performance in sub-Saharan Africa: barriers, opportunities, and scaling options. A review

“…In this study, barriers to scaling legume seed systems focused on the challenges and obstacles that limit the expansion of seed systems such as policy constraints or inadequate infrastructure. Barrier Legume crop References Poor soil quality affects the performance of some varieties thereby reducing the likelihood of adoption by smallholders Cowpea Anago et al ( 2021 ) Some legume crops/varieties have a greater susceptibility to pests and diseases resulting in lower yields. This can act as a barrier to the adoption of some legume varieties/crops by smallholders.…”

“…This can act as a barrier to the adoption of some legume varieties/crops by smallholders. Cowpea Anago et al ( 2021 ) Aflatoxin contamination negatively influences the cultivation of groundnuts in some smallholder farming communities Groundnut Boni et al ( 2021 ) Antinutrients in legume products can deter smallholders from producing/consuming certain legumes Grass pea Girma et al ( 2011 ) Restrictive policies can make the trade of legume seeds difficult Multiple Mulesa and Westengen ( 2020 ) COVID-19 had a severe negative impact on seed trade in the region Common bean Nchanji and Lutomia ( 2021 ) Lack of improved varieties (incl. early generation seed) and high seed cost Groundnut Sinare et al ( 2021 ) Limited access to land and gender issues around land tenure security (socio-economic factors) Multiple, groundnut Branca et al ( 2021 ); Sinare et al ( 2021 ) Limited access to other agronomic inputs (such as tools and fertilizers) Multiple Branca et al ( 2021 ) Insufficient access to credit and extension services Multiple Branca et al ( 2021 ) …”

Continuous assessment of cowpea [Vigna unguiculata L. Walp.] nutritional status using diagnosis and recommendation integrated system approach

“…Agricultural productivity is increasingly low due to progressive soil degradation and nutrient depletion 1 , 2 . Main soil nutrients (N, P, and K) as well as secondary and micro-nutrients are removed through harvesting, leaching, denitrification, erosion, and run-off.…”