Out-scaling 4R Nutrient Stewardship Knowledge to Support Crop Production Intensification in Ethiopia

Soil fertility has a major impact on crop productivity in smallholder cropping systems of Ethiopia. Thus, site-specific nutrient management (SSNM) is indispensable to optimize maize productivity and reduce the yield gap. Until very recently, fertilizer application in Ethiopia was based on a blanket recommendation in which only N and P fertilizers were applied. Fertilizer was also applied at a fixed rate across all maize growing regions, without considering the diverse fertility status of the soils in different regions. Soil fertility varies from farm to farm within a region due to previous agronomic practices, and the climatic variability. Uniform rate of fertilizer application in soils with variable fertility results in over application of fertilizer in some areas (in more fertile lands) and under application in other areas (less fertile lands).

The Nutrient Expert® (NE) fertilizer decision support tool was created for the development and dissemination of SSNM options to optimize management of N, P, K, and secondary, and micronutrients in maize. To provide SSNM options, location-specific guidelines are required that integrate soil, agronomic and climate information. Nutrient omission trials (NOT) were conducted for two seasons in four districts to calibrate the NE tool for maize. Results from the omission trials showed high potential to improve maize productivity with balanced fertilizer management. Balanced application of NPK and other limiting nutrients produced 11.8 t/ha of maize grain yield, which was about double the yields from the control (no application), and the N, P, and K omission treatments.