Isotopic studies on the uptake of sulphur by pasture plants

摘要

Abstract On two contrasting soils, Kowai sandy loam (recent soil) and Gorge silt loam (lowland yellow-brown earth) in inland Canterbury, New Zealand, plant uptake of 35S-sulphur placed at various soil depths and also the uptake of associated soil sulphur (32S) present at the same depths were investigated in developed pastures under field conditions. Results from the first harvest in spring 1972 showed that on both soils, white clover and perennial ryegrass plants used sulphur from all four depths studied (i.e., 7.5, 22.5, 37.5, and 52.5 cm). The relative contribution of roots, at each soil depth, to the 32S uptake was also assessed. With respect to the four depths studied, approximately 50% of the 32S uptake occurred at the 7.5 cm depth on both soils. Inclusion of the uptake from the 22.5 cm depth accounted for 76% and 90% of total 32S uptake in the Kowai and Gorge soils respectively. In the autumn 1973 trials, sulphur uptake (32S and 35S) from the 22, 52, 75, and 100 cm depths was investigated. On the Ko...