Soil quality evaluation under different agricultural land uses using multiple soil quality indices

Abstract

Assessing soil quality under agricultural production provides valuable information about the soil's condition and overall health. The study evaluated soil quality across different land uses (cassava, pasture, and maize) using multiple soil quality indices at the Federal University of Agriculture, Abeokuta, Nigeria. Profiles pits were dug at each land use type and described according to WRB guidelines. Soil quality was assessed using physical, chemical, geochemical and ecological (potential ecological risk coefficient and index) indicators. Soil pH (5.60-6.68), OC (0.63-3.03%), TN (0.02-026%), and Av. P (0.76-8.75 mg/kg) showed a decreasing trend with increasing soil depth. Bulk density (1.17-1.42 g/cm3) and Fe (17.50–65.63%wt) increased with depth, while other metals fluctuated across depths and land uses. Soil quality ranged from low to moderate, with low Av. P and K being the most common limiting factors. Geochemical indicators revealed minor to moderate enrichment for most metals, with Pb (13.884) showing moderate enrichment. Contamination factors indicated low to moderate contamination for most metals, except Pb (5.647), which showed significant contamination. The geoaccumulation index classified most metals as practically uncontaminated, with Ni (0.860) and Pb (1.913) indicating slight to moderate contamination. Ecological risk assessment suggested low potential ecological risk for most metals, but a moderate risk for Pb (28.235). The study concludes that combining different indicators provides a comprehensive evaluation of soil quality, highlighting the impact of agricultural practices on soil health. Regular monitoring and sustainable soil management are recommended to maintain soil quality and mitigate risks associated with heavy metal accumulation in agricultural soils.