Assessment of Rice Crop Water Requirements under Changing Climatic Conditions in Makurdi, Nigeria (1980-2024)

This study assessed the effects of climate change on rice water requirements in Makurdi, Nigeria. Reference evapotranspiration (ETo) and rice crop water requirements were estimated using the CROPWAT 8.0 model over a 45-year period (1980–2024). Climatic data, including temperature, rainfall, relative humidity, solar radiation, and wind speed, were obtained from the Nigeria Meteorological Agency (NMets) and subjected to trend and statistical analyses. The Mann–Kendall trend test and Sen’s slope estimator revealed significant increasing trends in maximum temperature, mean temperature, annual rainfall, solar radiation, and wind speed, alongside declining trends in relative humidity and minimum temperature. These climatic changes have contributed to a marked increase in both reference evapotranspiration and rice crop water requirements over the study period. Pearson Product Moment Correlation analysis indicated strong positive relationships between temperature, wind speed, evapotranspiration, and crop water requirements. Multiple regression analysis further demonstrated that maximum temperature, rainfall, solar radiation, and wind speed exert significant positive influences on evapotranspiration and crop water demand, whereas minimum temperature and relative humidity showed negative effects. The assessment of climatic water availability indicates a progressive decline in water availability in Makurdi, primarily driven by increasing evapotranspiration rates. The study underscores the growing challenges posed by climate variability on agricultural water demand and highlights the need for improved irrigation management strategies. It recommends targeted capacity-building initiatives by agricultural research institutions, including farmer training on decision-support tools such as CROPWAT, dissemination of timely climate information, and the development of drought-tolerant and early-maturing rice varieties. Overall, the findings provide a robust scientific basis for enhancing climate resilience and optimizing water resource management in rice production systems in the study area.