Properties of soils of different lithology in the humid tropics of southeastern nigeria

This study evaluated the properties of soils developed on diverse parent materials in Ogoja Local Government Area. Five profile pits on five different parent materials were dug, morphologically delineated and described. The five parent materials were basement complex (BC), mudstone (MS), sandstone (SS), shalestone (SH) and limestone (LS). Morphologically, the soils were deep with varying color, structure, texture and consistency. The results of chemical analyses revealed that the soils have acid pH with means of 5.4, 5.4, 5.4, 5.3 and 5.4 in BC, MS, SS, SH and LS. Organic carbon was low (<15g/kg) across the parent materials while total N was slightly higher in MS, SS and LS with means of 0.04 g kg-1, 0.10 g kg-1, 0.04 g kg-1, 0.10 g kg-1  and 0.20 g kg-1  in BC, MS, SS, SH and LS accordingly. Available P was low (<8mg/kg) across the parent materials with slightly higher value recorded in SH than in other parent materials. Calcium and sodium were the dominant and the least bases respectively with mean values of 3.2 cmol/kg, 3.93 cmol/kg, 3.65 cmol/kg, 3.3 cmol/kg and 3.95 cmol/kg and 0.25 cmol/kg, 0.10 cmol/kg, 0.08 cmol/kg, 0.08 cmol/kg, 0.08 cmol/kg in BC, MS, SS, SH and LS respectively. Exchangeable bases were higher in MS than other soils. Both Al3+ and H+ contributed at the same level to acidity of the soils. Correlation analysis showed that sand correlated negatively and significantly with clay (-0.81), OC (-0.41), TN (-0.42), and Al+++ (-0.78) and positively and significantly with pH (0.72), Ca2+ (0.7), Mg2+ (0.64), K+ (0.56), ECEC (0.71) and BS (0.70).  Correlation between pH and exchangeable bases, available P (0.83), ECEC (0.9) and base saturation (0.83) was significant and positive.  However, most properties had negative and non-significant correlation with each other.