Volume 10, Issue 22, July - December 2024

Mineralogy and physicochemical properties of soils at topounits along toposequence of shale derived soil in a tropical rainforest zone, Nigeria

Nwosu OC¹, Eneje RC¹, Amanze CT^2♦

¹Michael Okpara University of Agriculture, Umudike, Abia State, Nigeria
²University of Agriculture and Environmental Sciences, Umuagwo, Imo State, Nigeria

^♦Corresponding author
University of Agriculture and Environmental Sciences, Umuagwo, Imo State, Nigeria

ABSTRACT

Sustainable crop production requires a correct understanding of the characteristics of soils on a landscape, which helps to curb the incidence of wrong generalization in soil use and management practices. This study was carried out to assess the mineral composition and physicochemical properties of soils at different positions along the toposequence of a shale-derived soil at Amaeke, Abia State. The experiment was laid out in a Randomised Complete Block Design involving topounit as treatment and of five (5) levels (crest, upper slope, middle slope, lower slope and valley bottom) with three (3) replicates each of disturbed and undisturbed soil samples randomly collected from each topounit to give a total of fifteen (15) observational units. The soil samples were processed and analzsed in a laboratory. Data obtained were subjected to analysis of variance using Genstat analytical software, while significant means were separated using Fisher’s Least Significant Difference at a 5% probability level. The results showed that the topounits had similar mineral composition and rating except the crest which in addition to other common minerals, contained hematite and goethite. The crest was highest in bulk density (1.71 mg / m3), clay flocculation index (79.94%), and mean weight diameter (6.11 mm), but lowest in sand content (41.61%), and the upper slope was highest in available water capacity (30.31%). The valley bottom was highest in available phosphorus (30.02 mg/kg), organic carbon (1.32%), total exchangeable bases (16.68 cmol / kg) and extractible iron (0.42 mg/kg), at the same time, the middle slope was highest in exchangeable potassium (0.29 cmol / kg). The topounits varied in the physicochemical properties in such a way that soil structural stability indices and chemical properties decreased and increased, respectively, along the descending part of the slope.

Keywords: Topounits, toposequence, bulk density, organic carbon, crest, valley bottom

Discovery Agriculture, 2024, 10, e20da1601

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DOI: https://doi.org/10.54905/disssi.v10i22.e20da1601

Published: 19 October 2024