[Characteristics and Influencing Factors of Soil and Crops Selenium Content in Eastern Sanjiang Plain]

Too identify seleniut（Se） content characteristics and influencing factors in soil and crops of Shengli Farm in eastern Sanjiang Plain, statistical analysis and correlation analysis were comprehensively used to analyze the test results of 83 groups of surface soil samples and 34 groups of crop seed samples. The results showed that the Se content in the study area ranged from 0.12 to 0.95 mg·kg^-1, with an average value of 0.37 mg·kg^-1, and the enrichment degree was stronger with an enrichment coefficient of 3.18. Oxidizable Se was the main Se fraction, accounting for 81%, 79%, 79%, and 80% of T-Se in marsh soil, white soil, dry land, and paddy field, respectively. The content of reducible Se was the lowest, accounting for less than 5%. The effects of soil physicochemical indexes on Se content differences mainly showed that Se was negatively correlated with pH and total potassium （TK） and significantly positively correlated with cation exchange capacity （CEC）, soil organic matter （SOM）, humus （HS）, total nitrogen （TN）, and total phosphorus （TP）. The average content of Se in different land use types was as follows： dryland > irrigated land > grassland > forest land, as the dryland soil with low pH and high SOM was more likely to enrich Se. Among different soil types, the average Se content in gleysols was the highest at 0.45 mg·kg^-1, which was higher than the average value in the study area. The average content of Se in the quaternary alluvial layer was the highest at 0.43 mg·kg^-1, and its parent material mainly consisted of lacustrine sediments rich in organic matter, which was one of the important factors in forming Se rich soil. The Se content in crops and root soil showed a negative correlation. Se in low pH or high SOM soil was not easily absorbed by crops, and its Se content was also controlled by the form of soil Se, which was positively correlated with available Se content and negatively correlated with oxidizable Se content. Therefore, it is suggested to reduce the amount of artificial fertilizer used in cultivated land as a means of increasing Se bioavailability to change the current situation of crop Se levels in this area.