Uptake of native and applied selenium by pasture species

Uptake by mixed pasture of selenium applied as the element at 1, 4, and 160z per acre to a yellow‐brown loam was compared with that from selenium applied at 1 oz per acre as sodium selenite. Marked increases in Se content from additions as the element, proportional to the amount applied, were found initially. These are attributed to surface contamination of the leaves. The effect persisted into the second cut in the 16 oz Se treatment. In this cut the sodium selenite had Ithe greatest effect. After 11 months little increase above controls was apparent in any treatment. In a second trial on a yellow‐brown pumice soil, a comparison was made between treatments with 4 oz selenium per acre, in the forms of sodium selenite, ferric selenite, barium selenite, elemental selenium, and selenite incorporated in a “frit.” Again the trial was on a mixed pasture, but the clover constituent (mainly Trifolium repens L.) was dissected for Se determination. Uptake was greatest, and equal, from the three selenium salts. A passing effect from elemental selenium was again attributed to surface contamination. The “frit” showed the advantage of raising the selenium level in the initial cut, to only half that found in the selenite treatments, while proving equally effective at the end of 18 months.