Impact of Climate Change on Soil Wetness and Cocoa Production in Ondo State, Nigeria: Implication for Sustainable Farming Practices

Abstract

Cocoa is a strategic economic crop and a major source of foreign exchange for Nigeria, for which Ondo State is the leading producing area. However, its production has been marked with much fluctuation over the years with a reduction in yield of 40 to 50% due to insect menace. A study was conducted that covers all the Local Government Areas (LGAs) of Ondo State and datasets on rainfall, relative humidity, temperature, Surface Soil Wetness (SSW) and Root Zone Soil Wetness (RZSW) were sourced from the database of National Aeronautic Space Agency (NASA). The data were analyzed using the least square regression and correlation coefficient analyses. The results obtained showed that temperatures, relative humidity, the rainfall pattern as well as SSW and RZSW had similar impacts in 38.89% of the LGAs, while their effects varied in the remaining 61.11%. For the 42 years of observation, the temperature and relative humidity increased by 0.0033° C and 0.019% per annum at R2 values of 0.0045 and 0.0862 respectively while the rainfall decreased by 17.37mm per annum at R2 value of 0.1021.  The values of SSW and RZSW decreased by 0.0005 and 0.0006 per annum at R2 of 0.0451 and 0.036 respectively. There was a positive correlation of 0.152, 0.758, 0.762 and 0.995 between temperature and rainfall, rainfall and SSW, rainfall and RZSE as well as SSW and RZSW respectively. The correlations between temperature and relative humidity; SSW, RZSW and years of observations of -0.359, -0.212 and -0.190 respectively were inversed. This indicated that climate change had led to high relative humidity, temperatures and decreased rainfall, with a reduction in SSW and RZSW. High relative humidity favours the growth and development of various fungi that were noted for causing diseases of cocoa which necessitates the need for adoption of good agricultural practices (GAP) to mitigate reductions in cocoa production in the studied LGAs in Ondo state.