Radioactivity in agricultural phosphate-containing compounds

Total gamma-radioactivity has been measured in a number of agricultural phosphate-containing compounds: phosphate rock, apatite, commercial P-fertilizers, soil samples, gypsum samples and samples of animal fodder. It was found that, on average, the phosphate rock samples contained 2,311 Bq kg^-1 product and the apatite samples 1,502 Bq kg^-1. Expressed per unit P₂O₅, the apatite samples were 1.45 times more radioactive. The origin of the samples was not deterministic for the level of activity. The radioactivity of the commercial P-fertilizers varied between 500 and 3,000 Bq kg^-1. No influence of a long term low level application of P-fertilizers was noted on the radioactivity of the soil samples studied. Gypsum samples showed activities from 260 up to 2000 Bq kg^-1 while the activity in animal fodder was low (<100 Bq kg^-1).