| Abstract: | Abstract The release of CO2 from fresh soil at medium moisture was examined for 14 days after the application of gamma‐radiation over the range 0.025 ‐ 10 Mrad. All doses stimulated the release of CO2 compared with non‐irradiated soil, but there was no extra yield of gas between 4 and 10 Mrad. Rapid evolution occurred during irradiation and over the next 24 hours, but towards the end of incubation both irradiated and untreated soil produced CO2 at similar rates. Studies to elucidate the origin of CO2 indicated that the contribution from enzymes was predominant up to 2 Mrad, but at 10 Mrad, 45% of the gas could be formed by radiolytic decarboxylation of soil organic matter. Consequently, heavy irradiation of soil cannot stop production of CO2, and if high concentrations do interfere with the application of radiation to specific soil research investigations, the gas should be displaced or allowed to diffuse from the sample. |
