EVALUATION OF THE UNIVERSAL SOIL LOSS EQUATION (USLE) IN SEMI-ARID AND SUB-HUMID CLIMATES OF INDIA

Abstract

The Universal Soil Loss Equation (USLE) was evaluated for various crops in the semi-arid and the sub-humidregions of India. The predictions were made considering yearwise data of the experimental period as well as on an averageannual basis. Model efficiency based on the annual data series was relatively poor (0.46) in the semi-arid region comparedto the model efficiency (0.76) for the sub-humid region. However, on an average annual basis, the model efficiency improvedsignificantly to 0.81 in the semiarid region, and compared well to the annual series in the sub-humid region (0.75). Thecoefficient of determination (R2) between measured and simulated soil loss values was 0.88 and 0.91 on an annual basis, and0.93 and 0.94 on an average annual basis for the semi-arid and sub-humid regions, respectively. The soil loss predicted bythe USLE for the two regions and for both data sets was found to agree well with the observed data. The analysis of soil lossdata also revealed that simulated and observed soil loss values exhibited higher variation in the semi-arid region as comparedto the sub-humid region for both the annual and the average annual data sets, which was attributed to erratic and unevendistribution of rainfall in the semi-arid region. The Students t-test between observed and simulated values revealed thatUSLE estimates were not statistically different from measured values at the 1% level of significance on an annual as well asan average annual basis in the semi-arid and the sub-humid regions of India.