Migration and Transformation of Se in the Soil-Rice System

The interrelationship between the spatial distribution of soil Se and its characteristic element combinations that indicate different origin materials of three high quality rice-cultivating areas in Jiangmen city(Douhu,Niujiang and Zhaiwu) of Guangdong province was study.The results showed that soil Se in those areas resulted from continental deposits,of which the base source contributed more to soil Se than the granite source.Of the seven Se species studied,the species strongly bound in organic compounds and the humic acid-bound species accounted for more than half of total Se content,and the correlation coefficient between these two Se forms and total Se was high,indicating that the enrichment of Se in soil is closely related with organic matter activities.The distribution,migration,and the total transmission of Se in the roots,stems,leaves,chaff and grain of rice constituted a dynamic process.The Se transferred upward from the soil and the roots was gradually accumulated in various organs,the concentration factor being in the order of C stem-chaff C soil-root C stem-grain C root-stem.Se content of the shoots of rice was less than 50% of total Se of the plant.Total soil Se of the high-Se areas was related to organic Se and residual Se in the soil.The content and forms of Se were significantly affected by soil pH,Eh and organic matter content.