Abstract: For the purpose of reducing cost and preparing suitable pig feed, three combinations of fermentation mattresses were designed, i.e. 40% rice husk+ 60% mushroom bran (FJ), 40% rice husk+ 60% sawdust (FD) and 40% rice husk+ 60% vinasse (FW), in an experiment to explore  accumulation and activity of Cu in the surface soil at the bottom of the fermentation bed relative to type of fermentation mattress. Results show that after one production cycle, Mmattress FW was found to be higher in Cu absorption capacity, and Cu content in the mattress was 2.02 times higher than the background value. Combination of the mattress did not have much effect on bioavailability of the Cu in the mattress. However, bioavailability of the Cu in the surface soil under Mattress FJ reached 16.86%, obviously higher than those under the other two mattresses(P<0.05). Among the three types of mattresses, Mattress FD was in between the other two in Cu absorption capacity with Cu concentration being 198% higher than the background value, and the concentration of the Cu leached into the soil was 119% higher than the background value and availability of the Cu was 8.37%, the lowest among the three mattresses. From the angle of minimizing Cu pollution, Mattress FD is superior to the other two.Ecological risk assessment indicates that the potential ecological risks of the three fermentation mattresses and their underneath topsoils are still below the threshold of light ecological risk. In order to control Cu pollution while preserving nutrients in the organic manure, it is recommended that a fermentation bed should not last for more than three years.

Key words: fermentation bed mattress, Cu accumulation, available heavy metal, potential ecological risk assessment, material flow analysis(MFA)