Assessment of the extent of soil degradation over different land uses in the Kebbi area, northwestern Nigeria /Evaluation de la extension de la degradation en suelos de diferentes usos en el area de Kebbi, al noroeste de Nigeria

This paper assessed soil degradation over different land uses in the Kebbi area, Northwestern Nigeria. The specific objectives entailed identifying major forms of soil loss in the study area, estimating soil loss and examining the responses of soil physico-chemical properties over dominant land use types. Slope angles were determined using a GPS, a handheld Abney level, ranging poles and a 30 m measuring tape while gully depths, widths and lengths were taken at 5 m-30 m intervals. Key soil physico-chemical parameters were determined using standard procedures. Descriptive statistics such as mean, standard deviation and coefficient of variation were used to summarize the data generated from the study. The analysis of variance and the student's t-test was used to test for significant association between and within pairs of land uses. The results show that slopes range from 4[degrees] - 16[degrees], while the magnitude of soil loss ranged between 3580.32 [m.sup.3] in K1 (Kalgo 1), 3550.89 [m.sup.3] in G2 (Goru 2) and 161.01 [m.sup.3] in A1 (Angwar Daji 1). Results show significance at p[less than or equal to] 0.05 in bulk density values over the different land uses with the highest bulk density value of 1.78 g/[cm.sup.3] in badland and lowest value of 1.35 g/[cm.sup.3] in plantation land use. Total nitrogen range between 0.01 - 0.38% with the least values in badland and scrubland, while soil base saturation is highest over plantation (76.3%) and lowest in badland (50.4%). The study concludes that the dominant geomorphic responses identified in the study area are gully initiation and development and a varying magnitude of soil degradation over the different land uses. The findings should facilitate policy initiation to rehabilitate degraded lands, adopt sustainable soil management practices such as tree planting while linking geomorphological information to infrastructural planning and development. Keywords: Keywords: Estimates, gully characteristics, soil degradation, land uses. Este trabajo evalua la degradation del suelo debido a su uso en el area de Kebbi, al noroeste de Nigeria. Los objetivos especificos i mplican l a i dentificacion de la s ra zones pr incipales de la pe rdida de su elo en el ar ea de es tudio, la estimation de esta perdida, y la evaluation de las respuestas de las propiedades fisicoquimicas del suelo en los tipos de uso del suelo dominantes. Los angulos de la pendiente se determinaron con un GPS, un nivelador Abney de mano, balizas, y un