Aggregate Stability Indices of a Typic Hapludult under Different Land-Use Types and Varying Depths at Umuahia

Soil aggregates stability is among the soil conditions influencing the fertility and quality of soils. This study was carried out to assess the implications of land-use practices and soil depths on aggregate stability indices. It was split-plot experiment in Randomized Complete Block Design (RCBD) with factors as; land-use practices (main-plot factor) and soil depths (subplot factor). The land-use practices were of four levels continuously cultivated land (CC), forest land (FL), grassland (GL), and oil palm plantation (OP) ; while soil depths were of five levels (0 – 20, 20 – 40, 40 – 60, 60 – 80, 80 – 100 cm). Treatment combinations were replicated nine (9) times such that (9) mini-pits of 100 cm each were randomly dug in the respective land-use, then disturbed and undisturbed soil samples were collected from specified depths. . Data generated from laboratory analyses were subjected to analysis of variance (ANOVA) using GenStat version 15. Results showed that there was significant (P ≤ 5%) difference in aggregate stability indices among the land-use practices and across the depths; also there was significant (P ≤ 5%) interaction between land-use practices and depths. The highest dispersion index of 29. 48 % was observed under the FL at 0 – 20 cm depth, while the highest clay dispersion index of 42. 31 % was observed under GL at 0 – 20 cm depth. Aggregated silt + clay increased with an increase in depth with GL having the highest value of 29. 98 % at the 80 – 100 cm depth. The highest and lowest clay flocculation indices were observed at the CC and GL across the depths, respectively. The highest mean weight diameter across the depths was observed at the OP while CC had the lowest across depths. Therefore, aggregate stability indices vary across soils of different land-use practices and depths; hence should be considered in soil management decisions.