Selenium Concentrations in Alfalfa From Several Sources Applied to a Low Selenium, Alkaline Soil 1

Two laboratory-prepared ferric hydroxy bi-selenites and CuSeOs applied to Portneuf silt ham in the field provided slowly available Se to alfalfa, resulting in Se concentration adequate but nontoxic for livestock. These materials have potential as Se fertilizers at low application rates. The ferric hydroxy bi-selenites offer little or no advantage over CuSe0s. Se from BaSe04 alone, BaSeO4—BaSO4 mixtures, and CuSe04 was absorbed by alfalfa in concentrations toxic to livestock A small fraction of applied elemental Se was available immediately after application, providing adequate Se to alfalfa for livestock. The remaining elemental Se was rather inert, and supplies only slightly more Se to alfalfa than did the untreated soil the year following application. Additional