Screening of Abiogenous Azotobacter and Its Growth Characteristics in the Sterilized Soil

The aim was to isolate and screen abiogenous azotobacter from soil,and observe its growth characteristics.The nitrogen free medium was used to separate abiogenous azotobacter.The Micro-Kjeldahl method was used to determine the nitrogen-fixing ability of the abiogenous azotobacter in order to observe its growth promoting effect in rice seedling stage.The MPN method was used to detect the number of the azotobacter,and to study its dynamic changes in the soil.The results showed that the strain A2 of azotobacter was isolated and screened,which had strong Nitrogen-fixing ability and significant effect in promoting the growth of rice.The growing period of the strain was about 20 days in the sterilized soil,and soil nitrogen content was significantly increased.