With the increase of agricultural production, residues of crop are the main source of organic matter in the soil and they are alternatives to inorganic fertilizers. For this purpose, effects of organic residues (cotton stalk, maize stalk, almond bark) commonly grown in Turkey were investigated for some soil microbial activity in clay soil. In this study, incubation experiment was set up. Five doses (0%, 2%, 4%, 6% and 8%) of organic residues (maize stalks, cotton stalks or almond bark) were applied to soil. Soil microbiological properties of soil samples such as CO2 respiration, dehydrogenase and urease activity were determined. According to the results obtained, maize stalk, cotton stalks and almond bark applications increased some soil microbiological activities, such as CO2 respiration, dehydrogenase and urease activities according to control soil. Maize stalk in comparison to other residues affects better on the biological properties of the soil. It is determined that enhancing effects of the added organic residues (maize stalk, cotton stalk, almond bark) into the soil were changed according to the type of organic residues, dosage and application terms.