Aims: There are few studies on the effectiveness of this type of management on soil properties of Golestan province as the main agricultural pole in Iran. The purpose of this study is to investigate the effect of limited tillage on improving biological soil quality indicators. Methods: Three types of operations which include No Tillage (NT), Minimum or Occasionally Tillage (OT or MT) and Conventional Tillage (CT) were selected. From each management, 30 samples were taken at depths of 0-30 cm. Microbial respiration, microbial biomass, urease, acid and alkaline phosphatase, dehydrogenase and cellulase activity were measured. Findings: Conservation tillage (ST) which include both MT and NT increased acid and alkaline phosphatase by 1.6 to 2.5 times. The reverse trend was observed for cellulase, which showed a decrease from 37.5% in MT to 25% in NT. Urease and dehydrogenase increased by 14 and 18% in MT and decreased by 5.7 and 10% in NT. Microbial biomass and microbial respiration increased by 1.8 and 2.5 times in MT and in no tillage, operation decreased by 15 and 44%. Conclusion: The emphasis is on the advice of ST, However, it seems that some points related to the promotion of this method in agricultural lands should be considered. It seems that MT has a better condition for enzyme activity than NT. Low enzyme activity in NT conditions may reduce the availability of nutrients and thus reduce the yield, then extension experts should be inform the Farmers.

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