Study: Heavy metal content from inorganic fertiliser use
A study carried out by the Department of Agroecology at Aarhus University, Denmark, found that agricultural use of inorganic fertilisers does not pose a problem in terms of complying with the maximum permissible levels.
The Danish Ministry of Food, Agriculture and Fisheries commissioned the study, which covers the contents of arsenic, lead, cadmium, chromium, mercury and nickel in maize, barley, clover and winter wheat grown at different levels of fertilisation (from unfertilised to twice the standard amount). The effect of inorganic fertiliser was compared with that of livestock manure.
The content of arsenic in the crops was barely detectable, irrespective of the level of fertilisation. The contents of lead, chromium, mercury and nickel were generally low and could not be related to the amounts of fertiliser applied.
For crops that received inorganic fertiliser around the period of growth, a direct correlation was found between the amount of fertiliser applied and crop cadmium content. But the cadmium content of crops was in all situations below the maximum limits for feed stipulated by the EU. Especially barley and wheat had very low levels of cadmium.
Professor Bent Tolstrup Christensen, who has been in charge of the report, concludes on the background of the results that the agricultural use of inorganic fertilisers does not pose a problem in terms of complying with the maximum permissible levels:
– Even with prolonged use of inorganic fertilisers in the quantities and qualities we have examined, the contents of arsenic, lead, cadmium and mercury in typical agricultural crops do not exceed the maximum permissible levels of these metals in the feed material. This is a positive result for both animals and humans.
The data for the report consists of analyses carried out on crops grown from 2009 to 2012 in the long-term fertiliser experiments at Askov Experimental Station (Denmark), results from previous Danish field trials, and results from two field trials conducted in Skåne (southern Sweden) from 2009 to 2012. No systematic differences were found in analysed heavy metal contents between the use of inorganic fertiliser and livestock manure. The cadmium content, however, was lower with the use of livestock manure. The maximum levels for arsenic, lead, cadmium and mercury in feed have been set by the Ministry of Food, Agriculture and Fisheries; no limits have been set for chromium and nickel.
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