Dual-purpose cowpea grain and fodder yield response to variety, nitrogen-phosphorus-potassium fertilizer, and environment

Addressing the challenges of food and nutrition insecurity in sub-Saharan Africa will require innovative agriculture production systems that support multiple objectives. Dual-purpose cowpea [Vigna unguiculata (L) Walp] varieties are expected to offer greater grain yields for human consumption and high-quality fodder for livestock in semiarid regions of Senegal. However, limited information is available on the effects of varieties and fertilizer on dual-purpose cowpea. The main objective of this research was to evaluate the grain and fodder yield of five newly released cowpea varieties (Kelle, Leona, Lizard, Sam, and Thieye) compared to traditional variety (Yacine) with fertilizer (nitrogen-phosphorus-potassium 6-20-10) and no-fertilizer application. Genotype x environment x management experimentations were conducted across three cowpea production zones of Darou Mousty (400 mm per year), Bambey (500 mm per year), and Boulel (700 mm per year) over three growing seasons (2019-2021) to compare the growth and yield parameters of the cowpea varieties. Results of the study showed a 40% grain yield advantage from the greater yielding (Leona) variety in this study compared with the lower yielding (Lizard) variety. There was an additional 22% grain yield increase from the application of fertilizer compared with the unfertilized treatment. The variety (Leona) that produced the most grain also produced the most fodder yields. There was 67% fodder yield advantage from Leona compared with fodder yield from the older variety Yacine. Across varieties, application of fertilizer increased fodder yield by 15% compared to the unfertilized control. Average grain yield in high-yielding environment (Boulel 2019, Darou Mousty 2019, and Bambey 2021) was 100% greater compared with average grain yield in low-yielding environments (Boulel 2021, Darou Mousty 2021, and Bambey 2019). Compared to Yacine, dual-purpose varieties increased net returns by 15%-58% or 13%-42% with early- and late-season cowpea sales, respectively. However, fertilizer application was profitable only when cowpea grain and fodder were sold later in the season. In general, cowpea number of branches, pod number, and pod yield increased with fertilizer application. We concluded that producers can adopt dual-purpose varieties and proper fertilizer management to increase grain yield, fodder availability, and profitability of cowpea production in Senegal. There was a 40% grain yield advantage from Leona compared with Lizard variety.Grain yield was 22% greater from the application of fertilizer compared with the unfertilized treatment.There was 67% fodder yield advantage from Leona compared with the older variety Yacine.Dual-purpose varieties increased net returns by 15%-58% or 13%-42% with early and late season cowpea sales.Fertilizer application was profitable only when cowpea grain and fodder were sold later in the season.