Climate Dynamics and Rain-Fed Tuber Crop Yield Cultivated by Small-Scale Farming System Under Global Warming in Wolaita Zone, Southern Ethiopia

Agriculture is a backbone of Ethiopian economy, contributing a vital role to food security and employment in rural communities. Climate change and variability have been adversely influenced, challenging the country’s efforts to ensure food security. As a result, this study investigated the association between climate variability and tuber crop yields in southern Ethiopia. Modified Mann-Kendal trend test and coefficient of variation were implemented to examine trend and variability while Seaborne bivariate kernel density was used to assess how climate variability has been related with tuber crop yields. The study has also evaluated the predictive potential of multivariate regression by means of coefficient of determination and root mean square error metrics. The rainfall characteristics showed increasing trend during spring, autumn and annually at a rate of 0.32 mm, 1.67 mm and 0.25 mm, whereas significantly decreasing in summer rainy season at a rate of 0.455 mm/year. Spring and autumn rainfall revealed moderate to high variability, posing risks to rain-fed farming. Days and night time showed increasing trend at a rate of 0.053 oC and 0.16 oC 1981-2021 period. A reasonable tuber crop yield was harvested with cumulative rainfall ranging from 450.0 to 650.0 mm during the growing season, day and night time temperature was between 23.0-26.0 oC and 11.5-14.0 oC. When day time temperature above 26.0 oC and night time temperature below 11.5 oC, sweet potato and taro yields decrease, and harvesting is utterly unexpected. The RF regression model proved to be the best model performing algorithm allowing for optimal yield prediction, assisting farmers and decision makers in better planning crop production and management. The high variability of spring rainfall and the decreasing trend of summer rainfall, combined with an increasing of temperatures, could reduce agricultural productivity, leading to food insecurity. Therefore, the yield of tuber crops can be improved by supplementing the rain-fed farming system with irrigation and applying modern farming techniques and operations by farmers. Moreover, the finding suggests that the need to carefully select plant varieties tolerant to high ambient temperature conditions, which will be more prevalent in the context of climate change. There is a need to intensify adaptation measures to minimize the negative consequences of climate variability to improve the adaptive capacity of sweet potato and taro farmers.