Accumulation of PTEs In Agricultural Soils: A Case Study Showing The Inability of The Current Legal Order And Legislation to Address Ecosystem Services
Start date: 11 November 2009
The overall provision of ecosystem services within agroecosystems is fundamentally dependent on soil processes providing services such as nutrient cycling/acquisition. The maintenance of good soil quality is, therefore, of great importance. One of the major threats to soil quality is the accumulation of potentially toxic elements (PTEs), such as heavy metals, within soil. PTEs enter agricultural soils principally through deposition from the atmosphere and the use of agricultural materials such as sewage sludge, animal manures and inorganic fertilisers.
The EU has recognised the potential harm and introduced controls on the agricultural use of sewage sludge to prevent PTEs damaging soil fertility and human health. There is also EC legislation to limit the content of contaminants in food by setting maximum levels for certain undesirable substances in animal feed, which provides for maximum allowable concentrations of elements such as arsenic, cadmium, lead and mercury; Furthermore, there is direct EC Regulation to limit the content of contaminants in human food, setting maximum levels for certain contaminants in foodstuffs, which includes limit values for PTEs and hence has implications on the quality of the soil improvers used in agricultural land. However with regard to inorganic fertilisers, the current EC regulation relating to fertilisers does not provide for heavy metal limits.
A fundamental failure of current legislation and policy is the lack of direct control on the inputs of PTEs from sources other than sewage sludge. This is despite the fact that decades of application of organic and inorganic fertilsers could lead to PTE concentrations in the soil, reaching levels that could affect sensitive soil processes that underpin the provision of ecosystem services.
The approach taken by the EU and the UK is consistent in the “classic tragedy of the commons” form. Attention to ecosystem services and the conservation of the natural capital principal of the soil, we posit, is not only consistent with multiple use management, but would alter the calculus to promote sustainable conservation of the soil and ensure a stream of ecosystem service revenues for future generations.