Burkina Rock Phosphate Fertilization Increases Nodulation and Yield of Cowpea under Zaï Cultivation in Sahelian Agro-ecosystem of Burkina Faso

Cowpea occupies a considerable place in the nutritional and economic balance of the rural population of Burkina Faso. However, its cultivation is marked by yield instability linked to soil depletion of nutrients, especially N and P, and irregular rains. The objective of this study was to evaluate the effect of phosphorus fertilization with the rock phosphate named BurkinaP, on the spatial and temporal variability of cowpea nodulation and yield. A multilocation test was conducted in 12 and 16 farmers’fields in 2013 and 2014, respectively, in 3 villages of 3 provinces of the northern region of Burkina Faso. Two treatments were compared: zaï without (ZS) and zaï with BurkinaP (ZP). Overall, dry weights of nodules and shoots at flowering stage, and grain at harvest, were significantly increased by BurkinaP. It is concluded that in soils where low availability of P limits crop yields of cowpea especially in arid sud-saharan areas of West Africa, the input of BurkinaP can improve cowpea N2-fixation, and increase and stabilize cowpea yields.