Selenium Geochemical Characteristics Of Soil-Crop System In Wuchang City,Heilongjiang Province

Selenium is a kind of trace element necessary for human beings,animals and plants.Too high or too low selenium content may increase the probability of human and animal diseases.The development and utilization of selenium-rich land and the planting of selenium-rich agricultural products have become the focus of current research,and the distribution of selenium-rich soil,the influencing factors and the wealth level of selenium-rich crop also need to be studied.Taking Wuchang City of Heilongjiang Province as the research area,this paper investigated the land quality of 276km~2 of main rice producing areas to find out the content of selenium in the soil in the current research area.The influence of different environmental factors on selenium was discussed,and the main factors causing the difference of selenium distribution were determined.At the same time,the selenium content in rice and root soil was statistically analyzed to explore the bioavailability of selenium and its influencing factors,It can better guide the development and utilization of farmland.It can be seen from the land quality survey report in this district,the average selenium content in the soil in the study area is lower than the national average level,which is only 0.245mg/kg.The selenium content in this study area is in the middle grade,which belongs to the full selenium level.The soil area that reached the national Se-rich land standard(?0.4mg/kg)was only 11.01km~2;The soil area that reached the empirical value of Se-rich land in Heilongjiang Province(?0.325mg/kg)was 28.33km~2.The selenium content of soil in the study area can meet the needs of human body,but the prospect of developing Se-rich land is general.The results of the study on the factors affecting the distribution of selenium in soil revealed that the total selenium content which is in surface soil was correlated with soil type and land use type to some extent,but the correlation was general.There was a certain correlation between soil nutrients and selenium,among which phosphorus,potassium oxide,total iron and organic carbon had a good correlation with selenium content,while other nutrients had a weak correlation.There was no clear correlation between soil p H and content of selenium.With the increase of distance from river,the trend curve of selenium content in soil showed a single peak or a double peak.The general trend of selenium content was that the farther the sampling site was from the river,the higher the selenium content was in the soil.The selenium content and its influencing factors in crops in the study area showed that all the maize samples collected in the study area were at the non-Se-rich level,and the Se-rich rate in rice seeds reached 59%,indicating that the Se-rich ability of rice was stronger than that of maize.Selenium content in rice and the root in the soil nitrogen,phosphorus,potassium and organic carbon and root in the soil nutrient elements such as selenium content and p H does not exist a certain correlation,but with hydrolyzed nitrogen,slowly available potassium,available potassium and acid soluble potassium correlation is obvious,and hydrolyzed nitrogen,slowly available potassium,available potassium and acid soluble potassium content are affected by many factors common,Therefore,it is speculated that the absorption coefficient of rice may be affected by several elements together,rather than the simple effect of a single factor.The above conclusions revealed the selenium content level of soil and crops in this region and its influencing factors,which has certain guiding significance for the development and utilization of Se-rich land and the reasonable application of fertilizer in the future.