Limits of site-specific fertilizer recommendations: Evidence from a Malawi experiment
Africa’s input subsidy programs have been the subject of a long-running reform debate. One strand of this debate proposes moving beyond blanket fertilizer recommendations toward more targeted ones that better reflect local conditions.
- fertilizers
By Thomas Assefa, Jonathan Atkinson, Hailemariam Ayalew Tiruneh, Joachim De Weerdt, Edwin Siyame, David J. Spielman, and Bjorn Van CampenhoutAugust 7, 2026
Key takeaways
- Fertilizer recommendations derived from soil tests of farmers’ plots, when provided on their own, produced no measurable change in fertilizer use or maize yields among Malawian smallholder farmers.
- The same recommendation paired with a $100 voucher raised fertilizer use on the soil-tested plot and lifted maize yields by about 20%.
- Yet voucher recipients generally did not follow the recommendations, spending the money on a mix of fertilizers closely resembling that offered by the standard subsidy program.
Africa’s input subsidy programs have been the subject of a long-running reform debate. One strand of this debate proposes moving beyond blanket fertilizer recommendations toward more targeted ones that better reflect local conditions. These recommendations can vary in their degree of granularity, ranging from those tailored to agro-ecological zones to plot-specific prescriptions based on soil tests from individual fields.
This approach is expected to increase the efficiency of fertilizer use compared to universal programs, an objective that has become especially important as international fertilizer prices have proven highly volatile in the wake of the war in Ukraine and conflict in the Middle East. These conflicts have raised the fiscal and economic costs of blanket subsidy designs and sharpened the case for spending scarce fertilizer budgets efficiently—matching nutrients to what each plot actually needs.
Malawi’s national fertilizer subsidy program is often highlighted in this reform debate. It subsidizes a 100-kg bundle of NPK (nitrogen, phosphorus, potassium) basal blend and urea topdressing distributed each season to eligible households. In a recently released working paper, we assess a modification to the national subsidy program that, at comparable cost, uses site-specific fertilizer recommendations and vouchers to improve the efficiency of input use.
Results from a year-long randomized trial across 113 villages in central Malawi suggest that this approach increases fertilizer use and maize yields, even though recipients did not follow the precision fertilization advice they were offered.