It is general accepted that organic amendments like compost and digestate have great potential to improve physical, chemical and biological status of soil. Different treatments for instance composting and digestion of organic waste will result in organic amendments with different chemical and microbial compositions. The effect of organic amendments with different chemical and microbial compositions on soil matrix is very complex and surrounded by riddles, especially the relationship with soil microbial characteristics and crop growth. In this project, environmental technology specialists and soil ecologists are going to cooperate and shed light on this complex context.