In this study, the effect of the use of chemical fertilizers on natural radioactivity levels in agricultural soil was investigated. For this purpose, virgin and agricultural (fertilized) soils were collected from Erbil city, the capital of the Iraqi Kurdistan Region. Gamma-ray spectrometry was applied using a high-purity germanium (HPGe) detector to determine the activity concentrations of ²²⁶Ra, ²³²Th, and ⁴⁰K in soil samples. The results showed that the range of activity concentrations for ²²⁶Ra, ²³²Th, and ⁴⁰K in virgin soils are (10.6-16.2) Bq/kg, (8.8-10.7) Bq/kg, and (241.8-340.9) Bq/kg, respectively, while the range of activity concentrations for ²²⁶Ra, ²³²Th, and ⁴⁰K in agricultural soils are (11.9-18.2) Bq/kg, (8.8-12.4) Bq/kg, and (247.7-338.3) Bq/kg, respectively. The obtained values of activity concentration show that the application of chemical fertilizers elevated the natural radioactivity level of the soil. The radiological hazard parameters were also calculated in both the virgin and agricultural soil samples and compared with the international dose safety limit in the soil.