Status of Available Micronutrients in Soil Profiles of Different Parent Materials in Imo State, Southeastern, Nigeria

The status of available Zn, Cu, Ni and Fe was studied in four representative soil profiles of different parent materials (Coastal Plain Sands, Alluvium, Falsebedded Sandstones and Imo Clay Shale) in Imo State, Southeastern Nigeria. Sample collection was guided by horizon differentiation. Available Zn, Cu, Ni and Fe were evaluated using double acid extraction method. Variation in distribution of available micronutrients studied was evaluated using coefficient of variation while the relationship between available Zn, Cu, Fe and Ni and selected soil properties was estimated using correlation and regression analyses. The results showed that in soil profile derived from Coastal Plain Sands, available Zn, Cu, Fe and Ni were low (mean=0.45 mg/kg), moderate (mean = 0.76 mg/kg), low (mean=0.65 mg/kg) and moderate (mean=2.89 mg/kg), respectively. In soil profile derived from Alluvium available Zn, Cu, Fe and Ni were low (mean = 0.75 mg/kg), moderate (mean=0.70 mg/kg), low (mean=1.15 mg/kg) and moderate (mean=3.34mg/kg), respectively. In soil profile derived from Falsebedded Sandstones, available Zn, Cu, Fe and Ni were low (mean=0.46 mg/kg), moderate (mean=1.46 mg/kg), low (mean=1.03 mg/kg) and moderate (mean=3.99mg/kg), respectively while in soil profile derived from Imo Clay Shale, available Zn, Cu, Fe and Ni were low (mean= 0.74 mg/kg), moderate (mean=0.92 mg/kg), low (mean=1.25 mg/ kg) and moderate (mean=4.56 mg/kg), respectively. The results further revealed high variation, moderate to high variation, low to high variation and moderate to high variation in the distribution of available Zn, Cu, Fe and Ni, respectively in soil profiles studied. Available zinc (r=0.46) correlated significantly with OM while available iron (r=0.45) and nickel (r=0.47) had significant positive correlation with clay. Multiple regression analysis showed that the combined effect of available P, Ca, clay, ECEC, OM and pH on available Zn, Cu, Fe and Ni was not significant at 34.9 %,18.4 %, 38.9 % and 21.5 % respectively. Application of Iron and Zinc Chelates to all the soils of different parent materials studied and Nickel containing fertilizer is recommended particularly to soils of Imo Clay Shale