Characterization And Classification Of The Inland Valley Soils Of Central Cross River State, Nigeria

Abstract

Six profiles located in the inland valley soils of central Cross River State were studied. The surface horizon colour of the first four were either dark Grey or dark brown. The last two profiles were grey. All subsurface horizons were either greyish or brownish and highly mottled. The structure of all the profiles were either blocky or prismatic with the latter predominating for the subsurface horizons. The textures of the surface horizons ranged from sandy loam to clay while the subsoil soil horizons were predominantly clay. The pH of the soils ranged from acid (4.7). to neutral 7.4 The percent organic carbon content decreased slightly irregularly with increase in depth with the top soils concentration generally high. Similarly, percent total nitrogen was high with most values greater than 0.2%. However, concentration of available phosphorous was moderate. The exchangeable cations Ca. Mg and K were high. Exchange acidity of the soils decreased with increase in profile depth. Cation exchange capacity results were appreciable for four of the six profile with their base saturation values greater than 50% for the surface horizons. Using the criteria of the USDA Soil Taxonomy, profile APT – 1 was classified as Aeric Epiaqulfs, APT – 2 as Typic Epiaqualfs, ABN – 3 as Typic Umbraqualfs and ABN – 4 as Vertic Epiaqualfs. Profiles APP – 5 and APP – 6 were classified as Typic Epiaquults. Using the FAO – UNESCO soil map of the world legend, profiles APT – 1 APT – 2, ABN – 3 and ABN – 4 were classified as Gleyic Luvisols while APP – 5 and APP – 6 as Gleyic Alisols.



KEY WORDS: Characterization, classification, inland valley soil, surface horizon, subsoil horizon.

Global Journal of Agricultural Sciences Vol.3(1&2) 2004: 25-34