Pearl millet-cowpea cropping systems responses to fertilizer in the Sahel

In Niger, the pearl millet/cowpea intercropping system is widely used for various reasons. A study conducted in 2021 and 2022 aimed to confirm previous reports of the land efficiency benefits of this system and to document its differential response to fertilizer application with and without subsidies. The experiment included six treatment combinations: three cropping systems (pearl millet and cowpea sole crops, and pearl millet/cowpea intercrop) and two fertilizer levels (F0 and F1—100 kg ha?¹ NPK for all crops and 50 kg ha?¹ urea applied to pearl millet). The pearl millet/cowpea intercrop performed better during the low rainfall season of 2021, with a land equivalent ratio (LER) of 1.20. However, during the higher rainfall season of 2022, the intercropping system performed similarly to the sole cropping systems. Without fertilizer subsidies, the value-cost ratio (VCR) for the pearl millet/cowpea system was below 2 in 2022, indicating no return on fertilizer investment without government support. Although higher yields and greater fertilizer responses were observed for the pearl millet and cowpea sole crops, producers often prefer intercropping for its higher land use efficiency, more reliable yields, and production of a wider range of end-use products. Key words: Intercrop, sole crop, land equivalent ratio, value to cost ratio.