Soil-to-plant transfer factor (TF) is frequently employed to evaluate the effect of soil radioactivity on crops. The International Atomic Energy Agency’s collection of TFs for the tropical ecosystem was lacking in data from African nation, and there is a dearth of information on TFs in Nigeria. With the use of gamma spectroscopy, the activity concentrations of naturally occurring radionuclides in agricultural soils and frequently consumed food crops (Cassava, Cocoyam, Maize and Yam) were evaluated at five farmlands in the southwest region of Nigeria. The mean activity concentrations ( \({\text{Bqkg}}^{-1})\) of 40K, 226Ra, and 232Th for farm soil samples are 138.44 ± 50.30, 27.86 ± 14.77, and 81.15 ± 15.47 for Itagunmodi; 119.06 ± 65.96, 46.61 ± 37.37, and 91.84 ± 22.36 for Sagamu; 709.71 ± 502.69, 44.15 ± 30.22, and 147.23 ± 49.95 for Olode; 365.57 ± 273.95, 37.39 ± 24.29, and 140.08 ± 71.30 for Igbokoda; and 56.74 ± 43.29, 18.73 ± 17.90, and 113.53 ± 24.40 for Epe. The activity concentrations of all the analyzed food crops were below their corresponding soil samples. The TF of 40K, 226Ra, and 232Th ranges from 0.007 (cocoyam) to 0.602 (yam), from 0.086 (maize) to 0.84 (maize), and from 0.029 (cocoyam) to 0.756 (cassava), respectively. The radionuclide levels in the plant crops are within the ranges reported by IAEA 2009. The findings of this study might serve as the foundation and future criteria for radioactive concentrations in soil and migratory variables for the various crops grown in the study region.
