Natural radioactivity measurements in agricultural soil, fertilizer and crops in some specific areas of Kingdom of Saudi Arabia

High Purity Germanium (HPGe) detector gamma-ray spectrometry with 500 cc Marinelli beaker geometry was used for radioactivity measurement in some specific areas of Kingdom of Saudi Arabia (KSA). The detection limits of Pb-210, U-238, Ra-226, Th-232 and K-40 in soil, fertilizers, and vegetables lie mostly below 1Bq/ kg. The activity concentrations of U-238 and Ra-226 in local phosphate fertilizers were measured in the range of 236.8-879.0 Bq/kg and 101.5-297.0 Bq/kg, respectively. The respective activity concentrations of U-238 and Ra-226 measured in one charge of German phosphate fertilizer are in the range of 552.7-790.0 Bq/kg and 280.6-317.0 Bq/kg. The activity concentrations of 232Th are assessed to have maximum values up to 2.24 Bq/kg in locally manufactured phosphate fertilizers. Local urea exhibited concentration level (Bq/kg) of Pb-210, U-238, Ra-226, Th-232 and K-40 below the detection limit. Mean values of activity concentrations of U-238 in agricultural soil of Wadi Fatima, Taif, Hada Al-Sham, Madina City and Abyar Al-MashiMadina are 21.7 +/- 3.24, 38.2 +/- 4.1, 17.6 +/- 2.1, 34.3 +/- 3.5 and 32.7 +/- 2.4 Bq/kg, respectively. The respective mean of Ra-226 activity concentrations in those areas are 12.16 +/- 1.16, 20.2 +/- 1.33, 11.21 +/- 0.4, 21.4 +/- 1.7 and 21.0 +/- 1.22 Bq/kg. The specific activity of Th-232 in the respective areas has been measured as 12.6 +/- 1.3, 25.3 +/- 0.8, 11.5 +/- 0.9, 20.4 +/- 2.4 and 20.0 +/- 1.2 Bq/kg. Activity concentrations of Pb-210, U-238, Ra-226 and Th-232 in the vegetable samples are mostly found in the range of 0.37 Bq/kg to 37.8 Bq/kg. The K-40 specific activity lies in the range of 44.4-196 Bq/kg. The calculated absorbed dose rates in the representative locations are 24.07-53.28 nGy/h.