Morphological characterization of soils on false bedded sandstone for the production of cocoyam and bitter yam in Enugu Ezike, Nigeria

Résumé

The successful management of land for crop production depends on understanding soil variation and its suitability for specific crops. This study characterized soils developed on false bedded sandstone used for cocoyam and bitter yam production in Enugu Ezike, Nigeria. Soil profiles were excavated, described morphologically, and sampled for physical and chemical analyses. Morphologically, the pedons were deep (up to 200 cm), with a dull reddish brown Ap horizon (7.5R 3/3) and reddish-brown subsoil horizons. Soil structure was weak to moderate and platy in surface horizons, becoming firmer with depth. Texture ranged from sandy loam at the surface to sandy clay loam and sandy clay in the subsoil, with bulk density between 1.34 and 1.60 g cm⁻³ and total porosity of 40-50%. Soil pH ranged from 5.1 to 6.0 (strongly to moderately acid). Soil organic carbon (0.14-0.68 g kg⁻¹) and total nitrogen (0.04-0.07 g kg⁻¹) were generally low, decreasing with depth. Available phosphorus ranged from 3.38 to 21.98 mg kg⁻¹ (low to high). Exchangeable calcium was the dominant base (0.40-1.40 cmol_c kg⁻¹), and cation exchange capacity was low (4.40-6.00 cmol_c kg⁻¹), indicating limited nutrient retention capacity. Land suitability evaluation classified the soils as not suitable (NS) for cocoyam and marginally suitable (S3) for bitter yam, with soil fertility as the primary constraint. Sustainable production of both crops requires improved fertilization and soil conservation practices to enhance nutrient supply and retention.