Assessment of Soil Moisture Storage In Nigeria Using Climatic Water Budgeting Approach

The estimation of soil moisture storage is fundamental to crop production, hydrological and biological processes. This study assessed soil moisture storage in Nigeria using the Climatic Water Budgeting Approach. Mean monthly air temperature and monthly rainfall data were collected from the archives of the Nigerian Meteorological Agency from 27 weather stations in Nigeria. The data were subjected to Climatic Water Budgeting Approach to compute the monthly soil moisture storage at different locations in Nigeria over two years with contrasting moisture conditions (1983 and 2003). The mean monthly air temperature data were used to estimate the monthly potential evapotranspiration (PE) while the PE in conjunction with the mean monthly rainfall and the soil water holding capacity of 250mm were used to calculate the monthly soil moisture storage. The results showed that most locations north of latitude 9°N recorded low soil moisture storage below 10 mm from April to July especially in 1983. The soil moisture storage was high in all the places in January and February due to low potential evapotranspiration and accumulated potential water loss (APWL). Most Places South of latitude 9°N recorded higher soil moisture storage between 20 mm and 100 mm from January to May compared to their counterparts north of latitude 9°N in both 1983 and 2003. The soil moisture storage attained 250 mm (100%) from July-October across Nigeria. This study concluded that the soil moisture varies spatially and temporally in Nigeria decreasing from South to North. A paired sample test revealed a significant difference between the soil moisture storage of 2003 and 1983 in Nigeria (p=.000).