Classification and assessment of agricultural potential of the lower Niger floodplain soils of Atani, Southeastern Nigeria

Abstract

The soils of Atani floodplain in Anambra State of Nigeria contribute significantly to the food production of the State, hence the need to understand their behavior in order to enhance their management and productivity. Profile pits were sited along three physiographic units viz: levee crest, levee  slope and flood basin. Soil samples were collected from the profile horizons and subjected to standard laboratory procedures. Characterization of the soils was based on their morphological, physical and chemical properties. Soil classification was carried out using the USDA Soil Taxonomy and correlated with FAO/IUSS World Reference Base. Its agricultural potential was assessed using the fertility capability classification. The soils were deep. Topsoil colour was dominantly blackish black (10YR 3/2). Mottles were pervasive; an indication of impeded drainage conditions. The soils were predominantly fine textured. Soil pH values ranged from 4.8 to 6.2. Exchangeable Calcium was low to moderate (2.6-8.2 cmol kg−1); Magnesium was moderate to high (1.6-6.8 cmol kg⁻¹); Sodium was high to very high (1.0-2.5 cmol kg⁻¹), while potassium was high (1.2-4.2 cmol kg⁻¹). Cation  exchange capacity values ranged from 11.6 to 42.6 cmol kg⁻¹. Total nitrogen was very low to low (0.14-1.12 g kg⁻¹), while organic carbon was low to moderate (0.4-15.2 g kg⁻¹). Available phosphorus was very low to high ranging from 0.93 to 31.71 mg kg⁻¹ while base saturation ranged from 64 to 93%. The soils were classified as Typic Fluvaquents (Typic Fluvisols), Fluvaquentic Endoaquepts (Endostagnic Cambisols) and Fluventic Endoaquepts (Endostagnic Cambisols) according to the USDA and FAO/IUSS. The fertility capability evaluation of the soils revealed that the pedons were Lgn in classification due to limitations in drainage.

Key words: alluvium, cambic horizon, Inceptisols, lithologic discontinuity