Plant uptake of sulphur and trace elements from pyrite applied on grassland

Abstract

The plant availability of sulphur and incidental elements in two types of pyrite (FeS2) and five different sulphates was investigated in perennial forage grasses at 16 sites in western and central Norway in three consecutive years. The sulphur fertilizers were applied on the surface in spring at a rate of 45 S kg ha-1 in the first and second years of the trial, while residual effects were measured in the third year. In the first and second years the DM yields and the amounts of sulphur removed by the herbage were significantly lower at plots treated with pyrite than at sulphate-treated plots. In the residual year the highest yields of DM and sulphur were obtained after application of FeS2. The present experiments indicated that sulphur in pyrites was less plant available than similar amounts of sulphur supplied as sulphates. However, use of pyrite increased yields of DM and sulphur from the second year on, compared to no application of sulphur. The ratio N/S was strongly influenced by sulphur fertilization. Nitrate-N concentration was found to be highest in plants grown on soil that was not supplied with sulphur. No increases in the soil or herbage content of hazardous heavy metals were revealed, but it has to be emphasized that the applied amounts of FeS2 were small and that the products were used for only two years. © 1997 Scandinavian University Press.