Nutrient omission trial site in northern Nigeria illustrating effects of soil nutrients deficiency on maize growth.

The Nutrient Expert (NE) decision support tool has been successfully adapted for use in developing fertilizer recommendations that addressed wide diversity of soil and climatic conditions in Ethiopia, Nigeria and Tanzania. IPNI collaborated with CIMMYT, IITA and researchers and extension service providers from the public, private and development sectors to develop and use NE to generate site-specific nutrient management recommendations tailored for individual or groups of smallholder farmers. Calibration of NE was based on data from 700 on-farm multi-location nutrient omission trials that were successfully conducted in a wide range of major maize production areas in between 2015 and 2016. The nutrient omission trials were designed as a diagnostic tool to identify which of the macro-nutrients N, P and K were limiting maize growth and yield, and determined other possible constraints related to soil secondary and micro-nutrients. The performance of NE was tested in farmers’ fields in each of the three countries and results showed improved yields, agronomic fertilizer use efficiency and profits over farmer management practices and current recommendations.