ABSTRACT:The study investigated zinc availability in relation to selected soil properties in a crude-oil-polluted Eutric Tropofluvent in Egbema, Southeastern Nigeria. For this purpose, three treatments have been applied: unpolluted soil, polluted without vegetation and polluted with vegetation with five replicates arranged in a randomized complete block design. Guided by transect sampling technique, soil sampling was carried out in June 2008. Soil samples were collected from the three different land units using soil auger at a depth of 0-20 cm. Standard laboratory procedures were adopted in analysing the soils. Soil generated data were subjected to analysis of variance and correlation analysis. Results showed highly significant variation (p = 0.01) in bulk density, porosity, silt: clay ratio, pH, effective cation exchange capacity, percent base saturation, total nitrogen, organic matter, available phosphorus, calcium: magnesium ratio and zinc. It was found that zinc was higher in crude oil polluted soils than in non-polluted soil and it was below critical limits. Zinc availability in relation to selected soil properties in the crude oil polluted soils indicated that clay and organic matter did not affect zinc availability, while pH and effective cation exchange capacity did. A study on zinc dynamics in crude-oil-polluted soils will certainly provide further information on the management of crude-oil-polluted soils since it is one of the key micronutrient for crop productivity.

Effective and efficient management of copper (Cu) in soils for optimum crop production and environmental conservation depends on proper knowledge of the various copper forms and fractions in soils as well as parent material. The distribution of forms of Cu in soils of different parent materials (coastal plain sands, alluvium, false-bedded sandstones and Imo clay shale) in Imo State, Southeastern Nigeria was evaluated using sequential extraction procedure, comprising of six fractions; water soluble (WS), exchangeable (EX), specifically sorbed/CO 3 bound (SSC), Fe-Mn bound (Fe-Mn), organic matter bound (OMB) and residual bound (RE) fractions. Soil was sampled at 0-15, 15-30, 30-45, 45-60 and 60-75 cm depths from each soil. Data obtained were subjected to analysis of variance and means separation was done by the procedure of Least Significant Difference at 5% probability level. Correlation analysis of the various Cu forms and some soil properties was also carried out. Results showed that the water soluble, specifically sorbed/carbonate bound, Fe-Mn bound, organic matter bound (OMB) and residual bound (RE Cu fractions differed significantly among the soils of the different parent materials. The Fe-Mn bound copper was the dominant fraction in most of the soils, contributing 41.53-46.63% to the total Cu, being highest in the alluvial soil (6.389 mg kg -1 ) and lowest in the Imo clay shale soil (2.231 mg kg -1 ). Moderate concentrations of available Cu (0.694-1.456 mg kg -1 ) were observed and significant differences were observed among the soils. Correlations among the different Cu forms (WS vs EX r -0.48; EX vsFe-Mn r −0.46) and some soil properties (OM vs Fe-Mn r −0.86; Ca vs RE r −0.59; Clay Vs Fe-Mn r −0.53) were determined. Please cite as: Okoli N.H., Uzoho B.U., Ihem E.E. and Okon M.A. (2019). Differential speciation and availability of copper in soils derived from different parent materials in Imo State, Southeastern Nigeria.

Application of animal manures for soil amendment plays a major role in the improvement of soil properties and enzymatic activities of a degraded Ultisol. This study assessed the effects of poultry manure (PM) and swine manure (SM) on the activities of catalase and urease enzymes and some soil properties. The PM and SM were applied at the rate of 30 t ha–1 each on experimental plots arranged in a randomized complete block design with three replicates. Soil samples were collected at day 0, 14, 28, 42, 56, 70 and 84 from 0-15 and 15-30 cm depths and analyzed for catalase and urease enzymes and some soil properties using standard procedures. The results showed increase in soil pH (in H2O) from 4.0 to 5.4 following manure application. At 0-15 cm soil depth, PM and SM recorded 28.1 and 28.8% increases in soil pH (in H2O), respectively. Soil organic carbon was highest (2.6 g kg–1) at 0-15 cm depth for soil amended with SM while the lowest value of 1.1 g kg–1was obtained at 15-30 cm depth for soil unamended with SM. In PM-amended soil, catalase activities ranged from 1.32 to 6.77 mg g–1 while its activities in SM-treated soil significantly (p < 0.05) varied between 1.55 and 8.11 mg g–1. Urease showed ranges of 0.72-3.90 mg g–1 and 0.96-4.71 mg g–1 in PM-amended and SM-treated soils, respectively. The results uphold that animal manures improve soil properties and are enzymatically controlled.

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