Validation of Universal Soil loss Equation for Selected Soil Locations in North Central Nigeria Using Rainfall Simulator

Abstract

Erosion control in Nigeria must be met with high standards in other to attain a sustainable agricultural practice to meet the demand of the growing population in terms of food production. The study is aimed at estimating soil loss using a locally made rainfall simulator and accertaining the performance of the Universal Soil Loss Equation (USLE) model in predicting soil loss in the study location. For this to investigated, experiments were conducted using rainfall simulators, which is readily not available in Nigeria due to its high cost. The drop velocity (DV) of the constructed rainfall simulator was calculated to be 8.101m/s and 2.443 m/s respectively when operated at maximum and minimum intensity. The performance test revealed that the experimental coefficient of uniformity (CU) and rainfall intensity for the simulator was 79.86 % at 31.79 mm/hr and 78.03 % at 16.08 mm/hr at maximum and minimum concentration respectively.  Two experimental plots of vegetative and bare plots to estimate soil losses. The maximum soil loss of 0.515kg/m² experienced from bare plot at maximum rainfall simulator intensity. Measurements and analysis in this experiment showed a strong correlation over a short term between erosivity index, R, and observed soil losses, which confirms the validity of Universal Soil Loss Equation (USLE) under the conditions of the experiment. Coefficient of determination (R²) between erosivity index R and corresponding soil losses showed a weak correlation for vegetative plot due to insufficient data of factors but a good correlation for bare plot over a short term. The overall results confirm the validity of USLE under the conditions of this experiment within this study area for a short period.