| Sumario: | Climate change poses a threat to the agriculture sector in Sub-Sahara Africa due to the reliance on weather for crop production and the low adaptive capacity of its farmers. While nitrogen fertilization and shifts in planting windows are widely promoted to increase maize production, their efficacy under future climates remains uncertain. The CERES-maize model (hereafter reffered to as DSSAT) was used to assess the potential impacts of climate change on the yield of two maize varieties with different maturity duration and the potential of increased nitrogen fertilization and shifts in planting windows as climate change adaptation in the Coastal Savannah of Ghana. The impacts of these options were evaluated using climate projections by Coupled Model Intercomparison Project—Phase 5 (CMIP5) climate models under two representative concentration pathways (RCPs) 4.5 and 8.5 in the mid-century (2040–2069) relative to the baseline climate (1980–2009). Yield reductions ranged from 14 % to 41 % for the Obatanpa variety (intermediate maturity) and between 18 % and 51 % for the Abontem (extra-early maturity) variety across the GCMs and RCPs. Reductions in yields were more severe under RCP 8.5 than RCP 4.5 scenario. Increasing nitrogen application from 30 kg N ha 1 to 60 or 90 kg N ha 1 improved yields and resulted in higher yield increase under the baseline climate than under future climate. This implies that the efficiency of fertilizers will decline under climate change and this would have a negative return on investments and environmental consequences. Conversely, delaying planting dates by 2–4 weeks in the main growing season significantly mitigated yield losses, resulting in yield gains of 4–23 % for Obatanpa and 8–29 % for Abontem across climate models. However, delayed planting in the minor season resulted in yield decline. Optimizing planting can enhance productivity in the major season and hence the livelihoods of farmers. Thus, optimizing planting schedules could be a viable adaptation strategy to sustain maize productivity under future climate whereas increased nitrogen fertilization may offer limited benefits. These findings are vital for policy planning and evidence-based decision making in the agriculture sector.
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