Trace Elements Status and Strength of Compacted Arable Soils of Akure Nigeria

Abstract

Trace elements in arable soils have become an environmental issue that it has to be investigated for sustainable agricultural production. Investigations were carried out in the laboratory to determine some physical, geochemical and mechanical properties of three (A, B, and C) arable soils. The properties investigated were shear strength, and trace elements status in the surface and subsurface horizons. Shear vane tester was used to measure soil shear strength and atomic absorption spectrophotometer was used to determine the trace elements status of the soils. The three profiles studied were predominantly clay loam in texture across the horizons except the profile B which was clay in the 30 - 40 cm depth layer. The specific gravity of the experimental soils ranged from 2.65 to 2.77. The plasticity index of the profiles A, B and C ranged from 8.6 to 10.7, 9.3 to 10.7 and 10.0 to 10.7, respectively. The soils were characterized by relatively low levels of identified trace elements. Results showed that 8.5 mg/Kg of lead (Pb) was the highest value of trace elements, while 0.3 mg/ Kg of Iron (Fe) was the lowest value of the soil trace element observed. The most notable characteristics of the soils were the low organic matter content and the predominantly acidic pH. The bulk density of the sample varied between 1.72 and 1.86 g/cm3. The range of the maximum shear strength of compacted soil was 150.75 to 156.14, 154.79 to 160.17 and 162.87 to 166.90 kPa for profiles A, B and C, respectively. The mean moisture content during the study varied from 14.5 to 18.9% (db). The data presented in this study is good for planning and soil management practice.

Key words: Soil properties; Trace elements; Shear strength; Moisture content; Soil profile