Assessment of Soil erodibility Indices and Soil wash in a miniature badlands at Gada Biyu, FCT Nigeria

Abstract

Gada Biyu is located within the Federal Capital Territory of Nigeria. The Federal Capital Territory is located between latitudes 8° 25´and 9° 25´ North of the Equator and longitudes 6° 45´ and 7°45´ East of Greenwich Meridian in the savanna region with Aw type of climate. The study site at Gada Biyu is located within the following coordinates: point A1 at 8°36' N, 6°54' E, point A8 at 8°36' N, 6°54' E, point E1 at 8° 36'N, 6°54' E and point E12 at 8° 36'N, 6° 54'E. Erosion pins and a soil auger were used during the 2010 rainy season to obtain data for assessment of soil wash and soil physical properties. Soil textural grades and organic matter content were determined in the laboratory by the hydrometer and Walkely-Black methods respectively. Rates of ground lowering were computed from exposed parts of the pins installed in the field after the 2010 rainy season, while erodibility indices were determined from textural grades and soil organic matter. Results of soil wash show a mean ground lowering of 17.32mm/yr over a mean slope of 27° at Gada Biyu Badlands implying a great loss of soil in the study site. Soil erodibility indices show mean values of 2.29% for critical level of soil organic matter content, 2.26 for clay ratio, 2.10 for modified clay ratio and 78.79% for dispersion ratio. These results imply that there was a great loss of soil structure and high susceptibility of the soils to erosion during a single rainy season. These findings suggest that the soils of the study site and those of the Federal Capital Territory in general are undergoing rapid degradation. Thus, it is recommended among other things, that the authority of the Federal Capital Territory should checkmate and control indiscriminate grazing, poor farming practices and construction activities on potential sites and areas already known to be susceptible to erosion, in an attempt to forestall rapid ground lowering and the future occurrence of badlands within the Federal
Capital Territory and its environs.

Key words: Badlands, Soil Degradation, Soil erodibility, Soil Particle Size, Soil structure, Soil wash