The effect of sulphate on the selenium content of pasture plants

Abstract

In the three experiments reported, the selenium content of pastures was shown to be substantially affected by applications of sulphate fertilizer. Where pasture yields responded to sulphur topdressing, selenium levels in the legumes present were reduced by as much as 50 per cent due largely to yield dilution effects. On a second site, where pasture responses to sulphur were not obtained, selenium levels were also depressed, in this case indicating the existence of an antagonism between sulphur and selenium. A subsequent nutrient solution culture experiment indicated that an antagonism existed between sulphate and both selenate and selenite forms, with the effects being much stronger in the case of the selenate. The implications in animal production of the effects of applied sulphur on pasture selenium levels and of the associated increases in pasture sulphur levels are discussed.