A leap towards unravelling the soil microbiome

As early as 1937, Franklin D. Roosevelt raised the importance of soil with his statement: “A nation that destroys its soil, destroys itself”. Soil is the groundwork of ecosystem functioning as it filters and stores freshwater, provides essential nutrients for plant growth, and regulates the earth’s temperature. Essential for this functioning is the abundance and diversity of the microbial life living in soil. However, as the majority of soil organisms are not culturable, for a long time it was impossible to identify all biota present in soil. Nowadays, using molecular markers (both DNA and RNA) as a proxy, it is possible to map soil communities much faster and in greater detail. Therefore, we have new opportunities to deepen our understanding of the soil microbiome in different contexts. One area of specific interest is the rhizosphere, soil in the direct vicinity of plant roots. Plants are able to influence the rhizosphere by releasing a broad range of carbon-containing substances in the soil, resulting in selection and boosting a subset of the soil living community. In this thesis the central aim was to explore to what extent plants are able to affect the rhizosphere food web to their own benefit under different circumstances. It was found that long term soil management practices are able to structurally change the soil microbiome but also plants are well capable of changing the local microbiome, to the extent that it exceeds the effect of management practices. Ahead of us lies the challenge to link soil biodiversity to soil function.