Impact of cadmium levels in fertilisers on cadmium accumulation in soil and uptake by food crops

Abstract

Cadmium (Cd) and other heavy metals (lead (Pb), arsenic (As), chromium (Cr) and zinc (Zn)) occur naturally in fertilisers but at variable levels. To determine whether or not levels of metals in fertiliser affect the absorption of Cd and other metals by agricultural crops, a greenhouse study was performed to measure the uptake of Cd and other metals from 7 different soils grounds treated with either mineral fertiliser with increasing levels of Cd and one type of animal manure (cattle manure). The results show that there is no significant difference in absorption of Cd nor on other metals when P fertiliser is used with levels of Cd varying between 0.04 and 60 mg Cd kg-1 P2O5. Differences in soil properties (e.g. acidity and organic matter content) in combination with the content of Cd in the soil control the short term (1 harvest cycle) variation of Cd concentrations in crops. Long-term (100 years) calculations on a field and regional scale, however, show that the content of Cd in P fertilisers does affect both levels in soil and that in crops. Dynamic model simulations at EU level indicate that accumulation of Cd in soil (arable and grassland) continues if the Cd content in P fertilisers exceeds 20 mg Cd kg-1 P2O5. The calculated average long-term relative changes in both soil and arable crops relative to current levels are in the order of magnitude of +0.2% if no more Cd is applied via P fertiliser to 12.1% to 16% if, at the European level the concentration of Cd in mineral P-fertilisers averages 60 or 80 mg Cd kg-1 P2O5 respectively.