Review on the content, specification of selenium and its availability in soils.

Abstract

As more selenium(Se)rich soil has been found, people begin to give more attention to the availability of Se for plant and humanbeings. However, current understanding for the content, specification and plant availability is not complete and accurate. By analyzing the past research on Se in soils, we believed that differences in backgrounds(soil types, climate)and hiding effect of various influential factors led to different results with regard to the relationship of soil Se with influential factors. There should be more controlled study and quantitativebased model to trace the genuine relationship between soil Se and Fe and Al oxide, p H, Eh and organic matter. For the regional Se balance within air-soil-water-plant system, air precipitation, Se volatilization and leaching should be more precisely monitored. Isotope technology(natural istotope and labelling)could be a good option for tracing transformation mechanisms of Se in soil-plant system and this would give more good scientific support for the increasing Se utilization efficiency.