Yield and profitability responses of cowpea to cropping systems and sowing seasons in Vitória da Conquista, Bahia State, Brazil

Cowpea (Vigna unguiculata) crops produce a poor yield in northeastern Brazil compared to the other regions. The goal of this study was to assess the effects of irrigated cropping systems and sowing seasons on cowpea yield and profitability in Vitória da Conquista, Bahia, Brazil. Field studies were performed in four experiments during the rainy and dry seasons during 2016/2017 and 2017/2018, which denoted harvests 1, 2, 3, and 4, respectively. A randomized block design was used for each experiment with four replicates and the following treatments for cropping systems: (1) manual weeding; (2) liming and manual weeding; (3) liming and phosphorus (P) fertilization at sowing, nitrogen (N) and potassium (K) topdressing fertilization, and chemical weed control; (4) liming and P fertilization at sowing, K topdressing fertilization, rhizobia inoculation, and chemical weed control; (5) liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control; and (6) seed pretreatment with cobalt (Co) and molybdenum (Mo), liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control. The technology added to cropping systems increased the number of pods per plant, pod length, seeds per pod, and 100-seed weight, irrespective of the rainy or dry sowing season. Economic analysis, in turn, showed that the technology decreased the total operating cost despite increasing the cost of mechanical operations, inputs, and materials because of the replacement of manual weeding by chemical weed control. However, these costs were not influenced by the sowing seasons. We concluded that technologically enhanced cropping systems, especially systems 4 and 6, improved grain yield and provided greater profitability, which translated into improved economic benefits for farmers. Conversely, the sowing season influenced profitability, which was higher for dry season harvests, when there was less product offered and prices became higher.