EVALUATION OF CONSUMPTIVE USE OF WATER FOR THE GEO-POLITICAL ZONES OF NIGERIA USING RICE AS A REFERENCE CROP

Abstract

This study focused on the estimation of crop water requirement of rice to avoid over or under irrigation which may negatively affect crop yields. In this study, agro-climatic data (2013-2024) were collected and analyzed. The data obtained include; minimum and maximum temperature (oC), relative humidity (%), wind speed (km/day), sunshine (hr /day) and radiation (MJ/m2/day). FAO Penman-Monteith model is a universal standard model used to compute the mean monthly reference evapotranspiration (ETo) using the mean monthly weather data for six weather stations in Nigeria. The mean monthly and annual ETo estimated for each weather station were multiplied by the average crop coefficient (Kc) of rice to determine the crop water requirements. The empirical crop growth stage coefficient is used to scale the FAO 56 Penman-Monteith model to a specific crop (Rice). The mean annual ETc computed by FAO 56 Penman-Monteith model for all the six zones were graphically compared to identify the differences in evapotranspiration losses across the study area. The study concluded that, irrigation practices are best done by estimating the consumptive use of water in order to avoid over or under irrigation which may negatively affect crop yields.