Impacts of rainy season onset uncertainty on maize yields in Ethiopia

Abstract:

Among Ethiopian staple crops, maize has the highest average yield but the most interannual variability, as it is highly sensitive to water stress. To maximize yield, maize is often planted early in the rainy season, which extends the growing season but risks planting during a “false onset” in which a prolonged dry spell follows planting, reducing yield or even requiring replanting. Rainy season onset forecasts have been shown to reduce this risk of false onset; however, their utility has not been quantified in terms of increased yield. This research therefore aims to quantify the yield gap associated with suboptimal planting times of maize. The Decision Support System for Agrotechnology Transfer (DSSAT) model is used to model this gap over a 35-year historical period at the woreda (local) level, using three planting times: a baseline scenario based on soil water content within a specified planting month, a “perfect knowledge” scenario based on the true onset date, and a forecast-informed scenario based on forecasted onset date. The relative benefits of each approach are considered both spatially and temporally, with emphasis on extreme years.