FORMS AND DISTRIBUTION OF EXTRACTABLE IRON AND ALUMINIUM IN THE SOILS OF THE LOWER SLOPE OF BOLORUNDURO CATENA, ILORIN, NIGERIA
Keywords:
extractable iron, aluminium, soils, lower slope, Bolorunduro catena, IlorinAbstract
Form and distribution of iron and aluminium oxides in four soil profiles representing the lower slope of a carena at Bolorunduro, llorin were studied. The ranges in the values obtained for iron oxide were 179-3821, 71-693, 4-143 and 1-7 mgs/100g. of soil; while for aluminium oxide the ranges in values were 94-434, 72-272, 5-198 and 14-72 mgs/10g. of soil in the DCB, oxalate, pyrophosphate and acetate extractants respectively. The distribution of these sesquioxides is a variable function of the profile depth.
Positive and significant correlations were found to exist between DCB-iron and clay. DCB-aluminium and clay, pyrophosphate-iron and clay, acetate-aluminium and clay and oxalate-iron and organic matter. Oxalate-iron was negatively correlated with clay, though the correlation was insignificant. The mean weathering indices calculated for the soils (silt/clay, DCB-Fe/clay. DCB-Al/clay. Oxalate- Fe/clay, Oxalate-Al/clay) gave values that increased with drainage impedance