Evaluation of Selected Soil Structural Properties of Different Land Uses in Oforola, Imo State, Nigeria

This study centered on evaluating selected soil structural properties of different land uses in Oforola, Imo State, Nigeria. Soil samples were collected from six different land-use types, namely, secondary forest, bush fallow, bare plot, cassava cultivated plot, oil palm plantation, and grassland vegetation. Soil auger was used to collect soil samples from each of the land use types at two (2) depths (0 – 15 cm and 15 – 30cm). The samples from each land use at different depths were composited, mixed thoroughly and sub-sample, and analyzed in the laboratory for selected physical and chemical parameters. The data were analyzed statistically using GENSTAT software Ver. 8.2 in Completely Randomized Design (CRD). The soils of the study area were principally sandy, with sand accounting for more than 65% of the inorganic mineral fragment in the soil at 0 – 15 cm depth and 15 – 30 cm depth. Land use effect on the dispersion ratio (DR) was significant (P ≤ 0.05) at the 0 -15 cm and 15 – 30 cm depth. However, oil palm plantation recorded significantly (P ≤ 0.05) higher dispersion ratio at the 0 – 15 cm depth. Bulk density was highest (1.57 g/cm3) in grassland vegetation and lowest in secondary forest and bush fallow (1.25 g/cm3). The bulk density values for bare plot, cassava cultivated plot and oil palm plantation were 1.51 g/cm3, 1.35 g/cm3, and 1.29 g/cm3, respectively. The total porosity of the soil was significantly higher in secondary forest (51.84%). Total porosity values for bush fallow, Cassava cultivated plot, oil palm plantation, bare plot, and grassland vegetation were 51.83%, 48.38%, 50.97%, 42.36%, and 40.08%, respectively. The proportion of water stable aggregates were significantly (P ≤ 0.05) influenced by the various land-use types. On the average, secondary forest and bush fallow had higher water-stable aggregates of various sizes compared to the cassava cultivated plot that had moderate water-stable aggregates. The least water-stable aggregates of various sizes were recorded in grassland vegetation and oil palm plantation. The mean weight diameters were significantly (P ≤ 0.05) influenced by various land-use types. Low mean weight diameter was observed for oil palm plantation, grassland vegetation and cassava cultivated plots. Based on the findings of the study, secondary forest and bush fallow land-use types possessed the most stable structural properties and also showed optimal impact compared to other land uses in Oforola soils, Imo State, Nigeria