Selenium Concentrations in Southeastern Missouri Soils and Its Impact on Livestock Nutrition

Abstract

Selenium is a trace element in animal nutrition provided through forage. Vegetation should accumulate adequate levels to meet this livestock requirement. This study assessed southeastern Missouri soils for their selenium concentrations. Multiple sites across southeastern Missouri were sampled, from which a total of twenty-six soils were collected. Parent materials ranged from coarse to fine-textured alluvium and terrace deposits, colluvium, loess, limestone residuum and rhyolite residuum from poor to well-drained soils. The mean whole soil selenium contents ranged from less than 0.1 mg Se kg-1 for the Kaintuck pedons to 1.0, 2.2, and 2.4 mg Se kg-1 for the Irondale, Killarney, and Frenchmill pedons. For individual soils, Menfro pedons were deep, well-drained soils developed in loess. Paired Menfro pedons having similar soil morphology and having A-E-BE-Bt-C horizon sequences were selected and the greatest selenium concentrations were in the argillic horizons. Soils having fine textures (clayey) had moderate selenium concentrations, whereas soils having coarse textures (sandy) revealed minimal selenium concentrations. A wide soil selenium concentration variation was shown; however, no toxic selenium levels were measured. Therefore, soil selenium toxicity is not a regional issue. Noting that soil selenium concentrations in medium to fine-textured soils are appropriate for providing selenium to livestock, the need to artificially soil incorporate selenium or add selenium into the livestock ration remains critical for coarse-textured soils.