Millet response to microdose fertilization in south–western Niger: Effect of antecedent fertility management and environmental factors

•DAP microdosing is most effective on low yielding plots.•Even on low yielding plots, microdosing bears a non-negligible financial risk.•DAP microdosing should be targeted to plots with low expected yields.•Microdose is effective at counteracting the negative impact of late sowing.•Microdosing could be used as an alternative famine mitigation strategy. Soil fertility is a major constraint to agricultural development in most of the Sahel, with P being the most limiting nutrient for millet production on acid sandy soils. To address this issue, microdose applications of P fertilizer have been widely advocated in recent years. However, little is known regarding the effect of farmer management practices and environmental factors on millet's yield response to this technique. For this purpose, 276 farmer demonstrations were setup across a 3-year period in the Fakara region, western Niger. Five strata were considered based on antecedent organic manure management (corralling or transported manure). At each demo site, conventional management was compared to basal microdose fertilizer application of DAP (2ghill−1), NPK (6ghill−1), or DAP (2ghill−1) with urea (1ghill−1) applied at tillering. Millet grain yields on control plots were low (84%