ABSTRACT In this work, a radiological technique which simultaneously measures soil bulk density and water contents accurately and quickly in a non-destructive manner at different depths of the soil profile of the major soil series of Central Southwestern Nigeria is developed. Undisturbed samples from Iwo, Ondo, Egbeda, Itagunmodi, Okemessi, Mamu, Origo and Jago soil series of Southwestern Nigeria were collected on monthly intervals from June 2006 to May 2007. Using gamma-ray energy pairs of 122 and 1112 keV; and 344 and 1408 keV obtained from europium-152 (152Eu) radionuclide, the attenuation coefficients for soil and water, μs, μw and consequently ρs and θv at varying soil depths of these series were calculated. Comparative gravimetric measurements of these soil parameters were carried out. Using the XCOM computer algorithm with the soil elemental concentrations obtained using the Energy Dispersive X-Ray Fluorescence analysis (EDXRF) technique, theoretical estimates of μs for the various soil series were obtained and compared with the experimental values. The result of the developed dual energy gamma-ray transmission technique was compared with the gravimetric measurement method and Pearson correlation coefficient (0.987, p < 0.001) was obtained for ρs and (0.996, p < 0.001) for θv. The results of the measurements showed that θv minima with values 0.1931, 0.1987, 0.2377, 0.2111, 0.1738, 0.1701, 0.2334, 0.2341 and minima ρs values of 1.21 g/cm3, 1.20 g/cm3, 1.02 g/cm3, 1.38 g/cm3, 1.12 g/cm3, 1.14 g/cm3, 0.64 g/cm3, 1.33 g/cm3 were obtained respectively for the soil series stated above in January. The maxima θv with values 0.3621, 0.4212, 0.3962, 0.3794, 0.3049, 0.2811, 0.4415, 0.4416 and maxima ρs values of 1.52 g/cm3, 1.67 g/cm3, 1.74 g/cm3, 1.69 g/cm3, 1.70 g/cm3, 1.68 g/cm3, 1.08 g/cm3, 1.54 g/cm3 occurred for these soil series respectively in July except for Mamu soil series which occurred in May. These correlated very well with the occurrence of the Dry and Rainy seasons in the study area. The results of the EDXRF analysis showed that maxima Iron, Fe concentrations of 5.0890 ppm at the depth of 90 - 120 cm into the soil profile, was obtained for Iwo series, 4.4691 ppm at 50 - 70 cm for Ondo, 6.3438 ppm at 15 - 30 cm for Egbeda, 6.6845 ppm at 30 - 50 cm for Itagunmodi, 5.0252 ppm at 90 - 120 cm for Okemessi, 3.4996 ppm at 30 - 50 cm for Mamu, 5.1191 ppm at 50 - 70 cm for Jago and 4.7193 ppm at 90 - 120 cm for Origo. Maxima Potassium, K concentrations of 2.9613 ppm at the depth of 50 - 70 cm, was obtained for Iwo soil series, 2.3315 ppm at 0 - 15 cm for Egbeda, 2.2763 ppm at 70 - 90 cm for Okemessi and 3.3636 ppm at 50 - 70 cm for Mamu. Maxima Ti concentrations of 1.4822 ppm at 0 - 15 cm was obtained for Ondo soil series, 2.5159 ppm at 15 - 30 cm for Egbeda, 1.8690 ppm at 90 - 120 cm for Itagunmodi, 2.2975 ppm at 15-30 cm for Okemessi, 1.6453 ppm at 0 - 15 cm for Jago and 1.0513 ppm at 30 - 50 cm for Origo.
Cite this paper
O. Adejumo and F. Balogun, "Using the Dual Energy Gamma-Ray Transmission Technique to Measure Soil Bulk Density and Water Content of Central Southwestern Nigerian Soils," Journal of Environmental Protection, Vol. 3 No. 11, 2012, pp. 1409-1427. doi: 10.4236/jep.2012.311160.
 O. O. Adejumo, “Soil Bulk Density and Water Content Measurement of Southwestern Nigerian Soils by Dual Energy Gamma-Ray Transmission Method,” Ph.D. Thesis, 2009.
 A. C. Moreira, O. P. Filho, F. H. M. Cavalcante, M. M. Coimbra and C. R. Appoloni, “Gamma Ray Transmission for Hydraulic Conductivity Measurement of Undisturbed Soil Columns,” Brazilian Archives of Biology and Technology, Vol. 50, No. 2, 2007, pp. 321-328.
 J. C. Corey, S. F. Peterson and M. A. Wakat, “Measurement of Attenuation for Cs and Am Gamma Rays for Soil Density and Water Content Determinations,” Soil Science Society of America Journal, Vol. 35, No. 2, 1971, pp. 215-219.
 J. W. Hopmans and J. H. Dane, “Calibration of a Dual-Energy Gamma Radiation System for Multiple Point Measurement in a Soil,” Water Resources Research, Vol. 22, No. 7, 1986, pp. 1109-1114.
 M. E. Grismer, D. B. McWorther and A. White, “Monitoring Water and Soil Movement in Soils at Low Solution Contents,” Soil Science, Vol. 141, No. 2, 1986, pp. 163-171. doi:10.1097/00010694-198602000-00010
 M. Oostrom, J. H. Dane, O. Guven and J. S. Hayworth, “Experimental Investigation of Dense Solute Plumes in an Unconfined Aquifier Model,” Water Resources Research, Vol. 28, No. 9, 1992, pp. 2315-2326.
 J. H. Dane, M. Oostrom and B. C. Missildine, “An Improved Method for the Determination of Capillary Pressure-Saturation Curves involving TCE, Water and Air,” Journal of Contamination Hydrology, Vol. 11, No. 1-2, 1992, pp. 69-81. doi:10.1016/0169-7722(92)90034-C
 H. Vine, “Latosols of Nigeria,” Proceedings of the 2nd Inter-African Soils Conference, Leopoldville, 9-14 August 1954.
 J. D’Hoore, “Third Draft S.P.I Soils Map of Africa,” Presented at Seventh International Congress of Soil Science, Madison, 1960.
 A. J. Smyth and R. F. Montgomery, “Soils and Land Use in Central Western Nigeria,” Government Printer Ibadan, Western Nigeria, 1962.
 R. W. J. Keay, “Derived Savanna Derived from What?” Bulletin de l’Institut Fondamental d’Afrique Noire: Series A: Sciences Naturelles, Vol. 21, 1959, pp. 427-438.