Differences in selenium concentration and bioavailability between paddy and dryland soils of China: A study based on literature collection and field sampling

Lack systematic understanding of differences in environmental behavior of selenium between paddy and dryland soils affects Se biofortification and leads to human Se-related health risks. Therefore, this study investigated differences in Se concentration and bioavailability between paddy and dryland soils using data collected from literatures and field sampling. Our analysis showed paddy soil Se concentration in Se-rich area of China was significantly lower than that in dryland soil. Selenium biological concentration factor of rice grain (BCFgrain) in Se-rich area was lower than that in non-Se-rich area attributed to higher percentage of selenite in available Se. Concentration and percentage of available Se were in dryland soil lower than those in paddy soil and this affected BCFgrain of maize, whereas BCFgrain of rice was further influenced by its Se transport capacity. The ranges of Se concentration in Se-rich paddy (0.14–3.63 mg kg−1) and dryland (0.45–1.17 mg kg−1) soils were derived using a linear regression model. The current soil Se concentration evaluation standard was only suitable for dryland but overestimated Se-deficiency and Se-toxicity levels in paddy field. The present study provides theoretical foundations for understanding Se concentrations and bioavailability in soils and selecting efficient and safe approach on cultivated land use.