Revisiting agroecological zone-based fertilizer recommendations for maize in Nigeria: evidence from field-level nutrient response trials

Aliyu, K.T.; Kamara, A.Y.; Shehu, B.M.; Mulungu, K.; Tofa, A.I.

Revisiting agroecological zone-based fertilizer recommendations for maize in Nigeria: evidence from field-level nutrient response trials

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Descripción

Fertilizer recommendations for maize in Nigeria are largely based on blanket agroecological rates for (nitrogen) N, phosphorus (P), and potassium (K). Given the high spatial heterogeneity in soil fertility, these recommendations are often inefficient and lead to suboptimal yield responses. This study evaluated a site-specific fertilizer recommendation (SSR) approach against the blanket regional recommendations (BRR) across five major maize-producing zones in the maize belt of Nigeria. Using data from 1,163 on-farm trials conducted between 2015 and 2017, site-specific nutrient requirements of N, P, and K were quantified. Mean SSR rates for all nutrients were consistently lower than BRR rates and exhibited high spatial variability across zones, with coefficients of variation ranging from 54% to 65% for N, 12% to 86% for P, and 11% to 100% for K. Spatial interpolation of the net benefit ratio (NBR) revealed that about 21 million hectares (94% of Nigeria’s maize belt) had NBR values > 1.0, demonstrating clear economic advantage of SSR over BRR. This advantage was primarily driven by reductions in P (~47%), N (~27%) and K (~26%) to the overall fertilizer cost. These findings underscore the need to revisit the agroecological zone-based fertilizer recommendations to improve profitability, enhance nutrient use efficiency, and support sustainable maize productivity.