Future climate implication on maize (Zea mays) productivity with adaptive options at Harbu district, Ethiopia

Maize (Zea mays L.) is one of the important food crops in Ethiopia with significant area coverage but the yield is very below as compared to its genetic potential. The major factors for the low productivity of maize are water deficit, low soil fertility and heat stress. Climate change may further reduce future maize productivity. This study was conducted with the following objectives (1) to evaluate the performance of the CERES-maize model for simulating phenology, growth and yield of maize (2) to assess impact of climate changes on maize productivity in two time periods (2030s and 2060s) and (3) to explore adaptive measures for maize crop under the changing climate. The CERES-maize model was first calibrated using the phenology, growth, and yield data obtained from field experiments. Future rainfall and temperature data were projected using the 17 General Circulation Models (GCMs) using the two climate change scenarios (RCP4.5 and RCP8.5). Well-adapted maize cultivar (melkasa-2) was used as a test crop. Three maize cultivars (short, medium and long maturity duration) and four levels of nitrogen (0, 46, 92 and 138kgNha(-1)) were evaluated as adaptive measures to impact of climate change on maize. The model calibration result showed that the root mean square error (RMSE) between the observed and the predicted values for anthesis, physiological maturity, grain yield and aboveground biomass yield were 1 day, 3 days, 112kgha(-1), and 814kgha(-1), respectively indicated well agreement between the simulated and observed values. The values during the model evaluation, were 1 day, 2.52 days, 540.9kgha(-1) and 755.3kgha(-1) for the respective parameters. The overall results showed that the crop genetic coefficients were properly determined. The result from impact analysis showed that anthesis, physiological maturity, grain yield and aboveground biomass yields will likely decrease in the 2030s and 2060s under both RCP scenarios. Mean grain yield may decrease by 14.15% in the 2030s and by 17.2%, in the 2060s under both RCPs. The management scenario indicated that changes in cultivars and use of nitrogen fertilizer will likely increase maize productivity under future climate conditions. We concluded that future climate may adversely affect maize productivity but the use of adaptation measures may reverse such impacts.