Effects of Rainfall Variability on Cassava (Manihot Esculenta) Yield in Ankpa Local Government Area, Kogi State, Nigeria

Abstract This study examined the effects of rainfall variability on cassava (Manihot esculenta) yield in the study area between 2004 and 2024. The research integrated meteorological data, cassava yield records, and field survey responses from 370 cassava farmers. Descriptive statistics, time-series analysis, correlation, and regression techniques were employed to assess rainfall trends and their influence on cassava productivity. Findings revealed that annual rainfall ranged from 1,090 mm to 1,610 mm, with a mean of 1,372 mm and a coefficient of variation of 11.9%, indicating moderate rainfall variability. Seasonal analysis showed that over 96% of rainfall occurs during the wet season, with 55.4% concentrated in the late rainy season. Trend analysis indicated a statistically significant increase in rainfall at a rate of 9.4 mm per year (R² = 0.48, p < 0.01). However, inter-annual fluctuations remained pronounced. Correlation results showed a strong positive relationship between cassava yield and annual rainfall (r = 0.734, p < 0.01) as well as seasonal rainfall (r = 0.781, p < 0.01), while rainfall variability had a significant negative relationship with yield (r = –0.658, p < 0.01). Regression analysis further revealed that rainfall variables jointly explained 69% of the variation in cassava yield, with rainfall variability exerting a significant negative effect on productivity. The study also found that 72.4% of farmers are male, 74.6% operate on less than 2 hectares, and 60% lack access to extension services, indicating limited adaptive capacity. Overall, results show that although rainfall is increasing, its variability and uneven distribution significantly reduce cassava yield. The study concludes that rainfall variability remains a major constraint to cassava production and recommends improved extension services, climate-resilient varieties, and water management strategies to enhance productivity and food security. Keywords: rainfall variability, cassava yield, climate change, agricultural productivity, Nigeria