Abstract

The study was conducted from 2022 to 2023 in Farta District, Northwestern Ethiopia, a highland area characterized by acidic soils, a sub-humid climate, and variable rainfall. Despite being a major farming zone for barley and other crops, low soil fertility limits productivity. This study aimed to calibrate and validate the DSSAT barley model for malt barley under varying nitrogen levels and application times. The study included 12 treatments of three nitrogen fertilizer levels and four application timings. The model accurately simulated grain yield, with a Root Mean Square Error (RMSE) of 354.88 kg ha-1 and a high d-statistic (> 0.97), showing similar trends for biomass and nitrogen uptake (RMSE 576.3 kg ha-1 and 0.38%). The DSSAT model showed strong accuracy in simulating barley growth, with improved performance during evaluation and less than 5% deviation in key growth stages, confirming its reliability across various nitrogen treatments and conditions. The model estimated grain yield with an RMSE of 354.88 kg ha-1 and Normalized Root Mean Square Error (NRMSE) of 14.14%, showing a strong linear relationship with measured yield (R² = 0.95). Applying nitrogen showed diminishing returns and increased environmental risks. These findings suggest that a targeted rate of 69 kg N/ha and three split applications were the most effective strategy for improving productivity and sustainability under the region’s specific soil and climatic conditions.