Effect of phosphate fertilisers 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 semirural location in the U.K.
Samples from 1861 to 1992 were bulked for 5-year periods
from two phosphate fertilizer-treated plots, now with soil
pH 4.9 (unlimed) and 6.5 (limed), respectively. Analysis
of Cd was by Zeeman correction GFAAS following a nitric
acid digestion. The data are compared with those from
control plots which have not received superphosphate.
On the unlimed plots, levels of Cd in the herbage from 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 concentrations in herbage were considerably greater on the phosphate-treated 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 Mg of Cd kg-1 year-1 since the beginning of the
liming treatment in 1903