Concentration of natural radionuclides in three major staple food crops cultivated around a fertilizer plant in Onne, Rivers State Nigeria and the cultivated soil samples were determined using gamma spectroscopy operated on a Canberra vertical high purity 3″ × 3″ NaI(TI) detector. The average activity concentration of 238U, 232Th and 40K was determined, for cassava flour (U 19.3 ± 5.0, Th 11.4 ± 3.3, K 426.9 ± 33.8) Bq kg−1, for yam flour (U 6.3 ± 1.8, Th 8.4 ± 2.6, K 227.0.9 ± 27.3) Bq kg−1 while for cocoyam flour (U 7.5 ± 2.7, Th 7.1 ± 2.3, K 195.8 ± 25.83) Bq kg−1. The mean activity concentration for soil samples is 18.7 ± 3.7 Bq kg−1, 18.0 ± 3.8 Bq kg−1 and 308.4 ± 22.4 Bq kg−1 for 238U, 232Th and 40K, respectively. These values obtained show enhanced 40K concentration which is attributed to the effluent discharge from a fertilizer plant and its applications to farmlands, but 238U, 232Th values are well within the global average and values reported in some regions and countries of the world. Radiation hazard indices obtained to estimate potential radiological health risk in both foodstuffs and soil samples are well below their permissible limit as set by UNSCEAR [Sources and effects of ionizing radiation (Report to the General Assembly), 2000]. The rate of radionuclides transfer from soil to crops was moderate with mean transfer factors of 232Th < 238U < 40K.