Abstract Gamma-ray transmission methods have been used accurately for the study of the properties of soil in the agricultural purposes. In this study, photon attenuation coefficient, porosity and field capacity of soil are determined by using gamma-ray transmission method. To this end, the soil sample was collected from Erzurum and a 2×2 in NaI (Tl) scintillation detector measured the attenuation of strongly collimated monoenergetic gamma beam through soil sample. The radioactive sources used in the experiment were 241Am, 133Ba and 137Cs. The mass attenuation coefficients of dry soil samples were calculated from the transmission measurements. The soil samples were irrigated by adding known quantities of water and the soil–water properties were examined. It was observed that gamma-ray transmission method for determination of the soil parameters has advantages such as practical, inexpensive, non-destructive and fast analysis.