EFFECT OF PHOSPHATE FERTILIZERS AND ATMOSPHERIC DEPOSITION ON LONG-TERM CHANGES IN THE CADMIUM CONTENT OF SOILS AND CROPS

Trends are reported in the Cd content of herbage collected and stored from the Park Grass Experiment at Rothamsted Experimental Station, a s emirural location in the U.K. Samples from 1861 to 1992 were bulked fo r 5-year periods from two phosphate fertilizer-treated plots, now with soil pH 4.9 (unlimed) and 6.5 (limed), respectively. Analysis of Cd w as by Zeeman correction GFAAS following a nitric acid digestion. The d ata are compared with those from control plots which have not received superphosphate. On the unlimed plots, levels of Cd in the herbage fro m the phosphate-treated plot were very similar to those on the control for the years to 1930; whereas from 1940 to the present, the Cd conce ntrations in herbage were considerably greater on the phosphate-treate d plot. On the limed plots, Cd concentrations in the herbage from both the phosphate-treated and control plots have remained similar to each other, although both plots exhibit a small increase of about 1 mu g o f Cd kg(-1) year(-1) since the beginning of the liming treatment in 19 03.