Influence of Forms of Iron and Manganese Oxides on the Physical and Chemical Properties of Soils Formed Over Mica - Schist in a Northern Guinea Savanna, Nigeria

Three forms of oxides of iron and manganese were evaluated on soils developed in mica-schist lithology within the basement complex formation of Taraba State, North-eastern Nigeria. The results from the three oxide forms namely; pyrophos- phate extractable (Mnp/Fep), oxalate extractable (Mnox/Feox) and citrate- bicarbonate-dithionite extractable (Mnd/Fed) examined were subjected to both descriptive and inferential statistics to analyse their trend and distribution in order to understand their influence on pedogenesis. Content of the three forms of man- ganese oxides were lower than those of the respective iron oxides (Mnp: mean – 100.44 mgkg-1, Mnox: mean – 128.72 mgkg-1, Mnd: mean – 144.96 mgkg-1 and Fep: mean – 1212.30 mgkg-1, Feox: mean – 1305.20 mgkg-1, Fed: mean – 2518.00 mgkg-1) at their corresponding horizons; and was attributed to the mineralogical constitution of geology of the study area. Content of organic matter (mean, 0.632 %) and organic carbon (mean, 0.366 %) were low (but highly significant - F = 2502, p = 216*** ) and was attributed to high mineralization rate caused by cli- mate of study area (northern guinea savanna); thus, had proportional effect on the oxalate extractable Fe and Mn as they are organic bound. Also, a strong signifi- cant difference (F = 187.6, p = 7.777***) between means of Mnox and Mnp em- phasized reciprocity in their pedogenic interaction. High content of Fe across the three oxide forms examined presupposes high plinthization on soils of the mica- schist.