[The efficiency of sterilization methods for different soils].

Three different soil types (two sandy materials and one till soil type) were sterilized with 14 different sterilization methods or variations. The cation-exchange capacity and specific surface of the soil samples were chosen as control parameters of physico-chemical modifications in the soils. Incubation of soil samples in the presence of Na-azide and HgCl2, in addition to tyndallization and fractionated heating of soil lead to a significant reduction of microorganisms. UV radiation and alternating freezing and thawing of soil had no influence on the number of microorganisms. The application of mercury-II-chloride did not lead to the expected sterilization, especially with till. A sterilization of soil is possible by using formaldehyde and ethylene oxide gassing, in addition to autoclaving and gamma radiation. No microorganisms could be detected in the soils after application of these sterilization methods. The cation exchange capacity of the soils was only slightly influenced with these methods. The use of gamma radiation seems to be the best method for sterilization of soils.