Clay Dispersion of Hardsetting Inceptisols in Southeastern Nigeria as Influenced by Soil Components

Abstract

Hardsetting soil properties are undesirable in agricultural soils because they hamper moisture movement and soil aeration. The soils of the floodplain of Niger River in eastern Nigeria hardsets upon drying, following dispersion, puddling, and slaking during the waterlogged period. Ten soil samples collected from a depth of 0–20 cm were analyzed for their properties. The soils are classified as Fluvaquentic Eutropepts or Dystric Gleysol (FAO). The objective was to investigate the influence of some soil properties on water‐dispersible clay (WDC) of the soils, which is the precursor of the hardsetting process. The total clay content (TC) correlated significantly with WDC (r=0.94**), whereas the water‐dispersible silt (WDSi) was higher than its corresponding total silt content. The WDC showed a positive correlation with dithionite extractable Fe (Fed), Al (Ald), and oxalate extractable Fe (Feo) (r=0.75*, 0.89**, and 0.76* respectively). Exchangeable Mg2+ correlated significantly with WDSi (r=0.70). Principal component analysis of the soil variables indicates that 15 soil components, which influence WDC as hardsetting properties, were reduced to 5 orthogonal components. The parameters that influence hardsetting properties are exchangeable Na+, K+, Ca2+, Mg2+, Fed, Alo, and Feo. Other soil properties are kaolinite, smectite, illite, and WDC, including soil organic carbon (OC), electrical conductivity (EC), and ESP. Therefore, those soil properties, which explain hardsetting characteristics most, are exchangeable Na+, Fed, OC, Mg2+, and Alo. There are negative consequences on the erodibility, runoff, infiltration and tillage of the soils at both submerged and dry conditions due to clay dispersion, low OC, and hardsetting behavior of the soil.