COMPARATIVE ASSESSMENT OF SOME PHYSICAL PROPERTIES AND ORGANIC MATTER CONTENT OF SOILS DERIVED FROM DIFFERENT PARENT MATERIALS IN AKWA IBOM STATE, NIGERIA

The study of soils derived from different parent materials is useful in formulating appropriate management schemes for soil health and agricultural production. A comparative assessment of some physical properties and organic matter content of soils formed from coastal plain sands (CPS), sandstone (SST) and river alluvium (ALV) was conducted in Akwa Ibom State, Nigeria. Topsoil samples (0 – 30 cm) were collected from ten points in soils of each of the three parent materials for laboratory analyses. The soil samples were analyzed for texture, macro and micro aggregate stability indices, soil water characteristics, bulk density and organic matter. Data generated were subjected to Analysis of Variance to compare properties of soils of the different parent materials. Significantly different means were separated using the Least Significant Difference at 5% probability level. Results showed that soils of SST and CPS parent materials both had loamy sand texture while that of ALV soil was clay. Bulk density of ALV soil (1.20 Mg m-3) was significantly lower (p≤0.05) than those of CPS (1.55 Mg m-3) and SST (1.39 Mg m-3).  Significantly higher (p≤0.05) mean weight diameter (MWD) (2.01 mm), aggregated silt+clay (51.96%) and clay flocculation index (89.00%) were observed in ALV soils than in CPS and SST soils while the dispersion ratio and clay dispersion index were significantly higher (p≤0.05) in CPS and SST soils than in the ALV soil. Alluvial soil had significantly higher (p≤0.05) saturation water content (SWC), field capacity (FC), permanent wilting point (PWP) and available water content (AWC) of 0.61, 0.45, 0.25 and 0.20 m3 m-3, respectively, than those of CPS and SST. Alluvial soil also had the lowest cumulative infiltration (3.05 cm) and saturated hydraulic conductivity (0.40 cm hr-1) relative to those of CPS and SST. The CPS soil had significantly lower (p≤0.05) organic matter content (2.07%) than SST (3.06%) and ALV (3.34%) soils. Cumulative infiltration (I) significantly and positively correlated with total sand (TS) (r = 0.710*) in the CPS soil, and Ksat (r = 0.681*), MWD (r = 0.829**) and CFI (r = 0.655*) in the SST soil. In the ALV soil, cumulative infiltration positively correlated with total porosity (r = 0.770**) and negatively with bulk density (r = - 0.770**). Saturated hydraulic conductivity (Ksat) had a positive correlation with SWC (r = 0.745*) and TP (r = 0.833**), but a significant and negative correlation with BD (r = - 0.833**) in SST soil. Field capacity (FC) positively and significantly correlated with TP (r = 0.638*) in CPS soil, and with MWD (r = 0.713*), CFI (r = 0.647*) and OM (r = 0.651*) in SST soil and with TP (r = 0.790**) and OM (r = 0.672*) in ALV soil. The correlations of FC with BD (r = - 0.638*) in CPS soil, with CDI (r = -0.647*) in SST soil and with BD (r = -0.790**) in ALV soil were significant and negative. MWD positively and significantly correlated with organic matter (r = 0.699*).  The clayey ALV soil will be suitable for paddy rice production and dry season crops due to its higher water retention capacity than the CPS and SST soils which will be better utilized for vegetable crop production under irrigation. The CPS and SST soils can also be applied to intensive crop production under rain fed condition and supplemented with irrigation.