Overall, we will analyze effects of ash from bio-fuel combustion to get exact information on the amounts of ash that can be returned to soil in a sustainable manner without significant consequences for environment and human health.

1. We will analyze toxicity of ash to soil organisms and provide toxicity threshold values (WP3).

2. We will characterize bioaccumulation of heavy metals in the food-web, and evaluate the risk of export by biological processes of heavy metals from ash-amended plantations (WP4).

3. We will analyze ecosystem services in the plantations with focus on carbon sequestration; trace gas emission, and nutrient-turnover and -loss (WP5).

4. We will assess the export of heavy metals with percolating water from the top layer with the risk of contaminating subsoil aquifers (WP2).

5. We will describe how heavy metal content varies in ash from energy-plants using bio-fuel across the country (WP1).

6. We will characterise the reduction in toxicity of ash amended with (i) organic matter such as biogas sludge, or with (ii) metal cations, which immobilise the heavy metals (WP3).