Decomposition of organic residues in soils. Transformations of sulphur, iron, manganese in soils, decomposition of pesticide. Biological nitrogen fixation: symbiosis (including grain legumes, trees, Azolla, pasture/forage) and non symbiotic; Biochemistry of nitrogen fixation (symbiotic and non symbiotic), methods of measuring biological nitrogen fixation (BNF), inoculation, mycorrhiza, methods of studying microbial ecology-antibiotic resistance and select-able markers, serology, gene typing and other methods of molecular biology; Biochemistry of nitrification, denitrification and nitrate reduction; Biochemical transformation of phosphorus, sulphur, hydrocarbons and pesticides. Legume bacteriology. Biochemical processes in the rhizosphere.