Evaluation of Selenium Bioavailability in Naturally Enriched Paddy Soils Based on Diffusive Gradients in Thin Films (DGT) and Its Influencing Factors
Selenium (Se) is an essential trace element for mammals, yet no universally applicable method exists for assessing soil Se bioavailability. This study validated the feasibility of diffusive gradients in thin-films (DGT) technology for accurately evaluating Se bioavailability in paddy soils under natural conditions, and analyzed Se migration in the soil-plant system, soil kinetic characteristics, and the influence of physicochemical properties on Se bioavailability. Rice plants and corresponding rhizosphere soil samples were collected and analyzed using three traditional extraction methods alongside DGT. Results showed that 96.7% of soil samples and 66.7% of rice samples met the selenium-rich standard, and Se content measured by DGT most accurately reflected soil Se bioavailability. The bioconcentration factor (BCF) of different rice plant parts indicated generally low Se enrichment in grains, with primary enrichment in rice roots. Correlation analysis revealed that adjustments in soil pH, organic matter (SOM), cation exchange capacity (CEC), and sulfur (S) content could effectively improve soil Se bioavailability. These findings underscore DGT's superiority over conventional extraction methods for predicting Se uptake, offering a robust tool for managing selenium-rich agricultural resources.