Applying NPK fertilizer at rates up to 93.7 kg/ha increased maize grain yield by 61.3% (1029 kg/ha) compared to no fertilizer. A microdosing rate of 63 kg NPK/ha produced yield and economic returns similar to the recommended 100 kg NPK/ha applied in rows. The 78.1 kg NPK/ha rate gave the highest gross margin and value-cost ratio across both unfavorable and favorable fertilizer-to-grain price scenarios. All fertilizer treatments had a value-cost ratio above the critical threshold of two, indicating low financial risk even without subsidies. Mechanized sowing and fertilization saved 10 man-days/ha compared to manual methods, making timely planting more feasible. Combining fertilizer microdosing with mechanization improves fertilizer use efficiency, reduces labor, and supports climate resilience.
In the drylands of West Africa, low-cost methods such as seed priming and microdosing of fertilizer can boost sorghum and millet yields, but their effectiveness depends on local rainfall. Over four years in Mali, microdosing 0.4 g NPK per hill (4 kg/ha) worked best in central Mali, while 0.8 g NPK per hill (20 kg/ha) was best in southern Mali. Seed priming helped in central but not southern Mali. Adding a urea top dressing (1 g per hill, 25 kg/ha) improved yields only in southern Mali. Sorghum responded better to microdosing than pearl millet. A decision tree was created to guide farmers on crop and fertilizer choices based on rainfall.
Maize grain yield increased with NPK microdosing rates up to 93 kg/ha, producing 1029 kg/ha (61.3%) more grain than the control in Mali. A rate of 63 kg NPK/ha matched the yield and economic return of the recommended 100 kg NPK/ha applied in rows. The 78.1 kg NPK/ha rate gave the highest average gross margin and value-cost ratio across two price scenarios. All fertilizer treatments had a value-cost ratio above two, indicating low financial risk even with non-subsidized fertilizer. Manual sowing and microdosing required 11.4 man-days/ha, versus 1.0 man-days/ha for mechanized operations, suggesting farmers will adopt microdosing only if mechanized.