[en] Taking into account the importance of distribution and transfer of radionuclides in the soil-plant system, especially in agricultural fields, the aim of this research was assessment of radioactivity contribution and transfer characteristics of natural radionuclides in agroecosystem. The measurement of the natural radioactivity distribution was conducted in organic and sustainable farming management systems. Statistical evaluation of the physical and chemical properties of soils subjected to different farming systems, revealed the existence of differences in some parameters. Balanced distribution of natural radionuclides in soil-crop system was observed. Radionuclide ⁴⁰K was the most accessible to the investigated crops via uptake from the soil, then ²³²Th and ²²⁶Ra. The obtained results are useful for understanding the behavior of the radionuclides and provide an insight into the cumulative deposition of radioactivity in the agroecosystem. (author)