EFFICIENCY OF DIFFERENT METHODS FOR STERI LIZATION OF DIFFERENT SOIL TYPES

Three different.soil types (two sandy materials and one till soil type ) were sterilized with 14 different sterilization methods or variation s. The cation-exchange capacity and specific surface of the soil sampl es 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 s oil lead to a significant reduction of microorganisms. UV radiation an d alternating freezing and thawing of soil had bo influence on the num ber of microorganisms. The application of mercury-II-chloride did not lead to the expected sterilization, especially with till. A sterilizat ion of soil is possible by using formaldehyde and ethyleneoxide gassin g, in addition to autoclaving and gamma radiation. No microorganisms c ould 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.