2012-07-18
Life Cycle Assessment of Phosphorus Alternatives for Swedish Agriculture
The tractor is spreading fertilizer that can content cadmium, a harmful substance. Photo: Kersti Linderholm, SLU
An LCA study has assessed the environmental impact of four ways to supply Swedish agriculture with phosphorus fertiliser of acceptable quality as regards cadmium content: Mineral fertiliser; certified sewage sludge; struvite (MgNH4PO4*6H2O) precipitated from wastewater; and phosphorus recovered from sludge incineration. These were examined with respect to impacts on global warming, eutrophication, energy demand and cadmium flows to farmland.
Using sewage sludge directly on farmland was the most efficient option in terms of energy and emissions of greenhouse gases, but also added most cadmium to the soil. Phosphorus recovery from incinerated sludge was the most energy demanding option and gave most emissions of greenhouse gases.
Despite great concerns about cadmium in Swedish fertilisers and sludge, it was found that almost no regular analyses for cadmium are made on imported food by the authorities, although food imports are constantly increasing. Total imports of cadmium with food are therefore unknown.
Contact information
Doktorand Kersti Linderholm, tel. 0243-253 039, 0707-511 713
Agrosystem, SLU Alnarp
Written by:
Mikael Propst