The efficiency of cassava–Bambara groundnut intercropping according to the sowing date of cassava

The objective of this study was to propose a profitable cropping association date between cassava (Manihot esculenta) and Bambara groundnut (Vigna subterranea, also known as voandzou) through the examination of competition indices. The association of the cassava varieties Allada agba, Bonoua, Six mois and Yacé with the bouquet and creeping morphotypes of Bambara groundnut was tested at different cassava sowing dates: 0, 15 and 30 days after sowing of the bouquet Bambara groundnut and 0, 15, 30, 45 and 60 days after sowing the creeping Bambara groundnut. These cropping association systems were evaluated through competition indices in Côte d’Ivoire: the area–time equivalent ratio (ATER), the competitiveness rate (CR) and the relative dominance coefficient (K). ATER and K values were greater than unity when cassava was sown 15 to 30 days after sowing the bouquet Bambara groundnut and 30 to 45 days after sowing the creeping Bambara groundnut. Cassava varieties were more competitive than the Bambara groundnut morphotypes (CRC > CRV). The best results in terms of efficient land use (ATER > 1) and yield gain (K > 1) were obtained when cassava was sown 30 days after Bambara groundnut. However, for the Bonoua–Bambara groundnut creeping association, the yield gain was obtained when cassava was sown 45 days after Bambara groundnut.