Determining the Best Rate of Blended NPKSZnB Fertilizer for Optimum Onion Yield and Yield Components in Northwestern Tigray, Ethiopia

Aim: The nutrient content of current fertilizer recommendations is unbalanced and is based on a very general and blanket recommendation for all soil and crop types, and their economic benefit is low. Therefore, this study was initiated to validate the recommendations regarding blended fertilizers applied to the soil and to identify the best fertilizer dose that ensures optimal yield and maximum economic return. Study Hypotheses: significance effect of blended NPKSZnB fertilizer on onion yield and yield components. Study Design: The experiment was designed using a randomized complete block design with three replications and seven treatments. Place and Duration of the study:  The field experiment was conducted in the off-season of 2018 and 2019 in Tahtay Koraro (two farmers), and Laelay adyabo (two farmers) districts of in northern Ethiopia. Methodology: Seven treatments with NPKSZnB fertilizer rates (25, 50, 100, 150, 200, 250 and 300 kg·ha-1) were tested under irrigation conditions.  Thus, for each plot nitrogen from Urea was applied at a rate of 150 kg ha-1. Surface soil samples were collected before planting onion harvesting at a depth of 0-20 cm to analyze selected soil chemical properties such as pH, extractable electric conductivity (ECe), cation exchange capacity (CEC), total nitrogen (TN), available P and exchangeable bases (K, Mg, Ca, and Na). Results: The application of different doses of NPKSZnB under irrigation conditions had a statistically significant (P < 0.05) impact on onion phenology, yield and yield components. The highest average onion yield (10,329 and 19,196 kg ha-1) was obtained after applying compound fertilizer doses of 200 and 250 kg ha-1 in Teahtay Koraro and Laelay Adyabo districts, respectively. However, the use of NPKSZnB fertilizer at a dose of 100 and 50 kg ha-1 for onion cultivation under irrigated conditions in T/koraro and L/adyabo districts was found to be economically viable. Thus, growers in both  districts should use NPKSZnB compound   fertilizer at these rates  for  onion  production and productivity. Conclusion: Therefore, farmers in both districts should use NPKSZnB compound fertilizer at these rates for optimum onion production.