Effects of Soil‐Applied Selenium on the Growth and Selenium Content of a Forage Species

This study was conducted to determine the effects of soil‐applied selenate and selenite on the growth and Se content of a forage species, sorgrass (Sorghum vulgare var. sudanense Hitchc.), grown on acid southeastern soils under different soil conditions. A greenhouse pot study was conducted using a factorial design, with two soil types varying in clay and hydrous oxide content (Blanton sand, a loamy, siliceous, thermic Grossarenic Paleudult; and Orangeburg loamy sand, a loamy, siliceous, thermic Typic Paleudult), two soil treatments (limed and unlimed), two Se forms (selenate, SeO2−4, and selenite, SeO2−3), and four Se concentrations (0, 1, 2, and 4 mg Se kg−1 soil). Additions of Se in the selenate form had a greater toxic effect on the plants, reducing plant biomass as much as 97% and increasing plant Se concentrations to as high as 1153 mg Se kg−1. Selenite additions generally did not affect plant biomass, but still resulted in accumulations of Se in aboveground tissues to levels potentially toxic to animals. Selenium concentrations were higher in plants grown on the soil lower in clay and hydrons oxide content. Liming resulted in lower tissue Se concentrations in plants grown on either soil treated with selenate.