Incidence of heavy metals in the application of inorganic fertilizers to rice farming soils (Valencia, Spain)

The presence of Cd, Co, Cu, Ni, Pb, Zn, Fe and Mn in different inorganic fertilizers (urea, calcium superphosphate, iron sulphate and copper sulphate) are evaluated and the contribution of these metals to the soils in this way is estimated. The studied zone corresponds to rice farming and is at the north of Albufera Natural Park (Valencia, Spain). The results obtained show that Superphosphate is the fertilizer that contains the highest levels of Cd, Co, Cu and Zn as impurities. Copper sulphate and iron sulphate have the most significant contents of Pb, and are the only fertilizers in which Ni is detected. The most significant additions of impurities that the soil received by agricultural practices were of the heavy metals Mn, Zn, Co and Pb. Two contamination indexes have been applied to provide a basis for comparison for heavy metal potential toxicity. These results denote no potential toxicity for heavy metals in the studied soils.