Spreading waste materials including animal manures on farmland is an important way of adding nutrients to the soil. Because farm animals may be given feed supplements or medicines containing metals, these can become present in their manure. This can lead to metal build-up in the soil, and runoff into adjacent waterbodies.
Predicting the metal build-up and runoff can help in:
- Making decisions on how to spread manure sustainably;
- Providing data for environmental impact assessment.
The Centre for Ecology and Hydrology (CEH) has developed a tool to predict how concentrations of copper and zinc in soils and waters increase due to regular inputs over the long term (decades and greater).
The tool builds on extensive CEH research in modelling the environmental chemistry of metals. Predicting over the long term is needed as the build up of metals to potentially toxic levels is gradual, but once present, they may remain in soils for decades to centuries.
Customers have confidence that the tool is built upon extensive research on modelling the environmental chemistry of metals and that the predictions can be used, for example, to inform policy on the maximum levels of copper and zinc that can be present in feed additives for different types of farm animal.
The European Food Safety Authority has referred to the outcomes of the work in proposing reductions in the copper and zinc content in feed additives for some animal groups.
The tool has subsequently been improved and re-evaluated for the European Copper Institute (ECI) and International Zinc Association (IZA). It has been recently used to assess the potential impacts of zinc in manure from a nanoparticulate zinc veterinary medicine in order to fulfil the European Union Authorisation requirements.
European Food Safety Authority (EFSA), European Copper Institute (ECI), International Zinc Association (IZA), wca environment ltd
A tool for predicting long-term metal risks in farmland soils and nearby water bodies
Informing policy on the maximum levels of copper and zinc that can be present in feed additives for different types of farm animal