Characterization, classification and assessment of soil degradation caused by mining activities in the farmland of College of Education, Minna

Abstract

This study aimed to characterize and classify soils, as well as evaluate the impact mining activities on soil degradation within the College of Education, Minna farm land. A free survey method of an area covering 60-hectare was conducted. Three soil units were identified, two in the upland mapping unit (UL1, UL2) and one in the dissecting valley (DV3). Three pedons were excavated, one from each of the identified soil units. The pedons were described and soil samples from each genetic horizon were collected for laboratory analysis. In addition, six composite soil samples at three different distances away from two mining sites were collected for soil heavy metals determination. Morphological properties revealed that the soils are generally gravel at the surface with texture ranging between sandy loam and sandy clay loam in the subsoil. The presence of a textural horizon (Bt) is common in all the soil units. Buried stone line was identified in UL2 an indication of a lithologic discontinuity. Soil reaction revealed a slightly acid to near neutral pH in the soils. Soil organic matter, Available P and Total nitrogen are rated medium. CEC and the exchangeable bases are low in the soils. Base saturation is generally moderate to high (46 % to 70 %). Low nutrient content in the soils may be attributed to the low activity clay, uptake by plant and little or no addition from fertilizer application. The values of EC, ESP and SAR indicate soils without salinity/sodocity problem. Heavy metals in the soils are generally low according to the limit set by WHO, with the exception of Cd (1.5-5.4 mgkg^-1). The soils could therefore, be referred to as Cd polluted. The farm land soils were classified as Alfisols according to the USDA Soil Taxonomy System and correlates with Lixisols in the WRB system.