Impact of Rainfall Erosivity on Soil Loss Rates in Biu Area, Borno State, Nigeria

Abstract

Soil loss rate from rill erosion is severe because of high rainfall erosivity in Biu Area. The aim of this present study is to assess the magnitude of soil loss from erosivity of rainfall in Biu Area. Rain gauges were installed at six locations; Kigir, Daura, Garwashina, Mirnga, Tum and Piku from April to October (2016), to measure rainfall amounts. Wishmeir and Smith 1958, 1978 models were used to calculate rainfall and runoff factor (R). The Revised Universal Soil Loss Equation 2, (2008) was to calculate erosivity and soil loss rates. The soil textures ranges from clay loam, loam, silty loam and sandy clay loam in the study area. Bulk density and percentage slope steepness ranges from 1.25 – 1.38 g/cm³and 10.5 – 12.0 %, respectively. Kigir, Piku, Daura, Mirnga, Garwashina and Tum sites recorded the erosivity of 726, 730, 780, 710, 715, 701 MJmmha^-1hr^-1and soil loss due to erosivity were 207.14, 248.96, 248.68, 243.02, 351.85 and 240.40 kgha¹yr¹, respectively. Both erosivity and soil loss rates were significant (P < 0.05) at locational bases. The models showed low to high prediction strength at locational and annual bases.