Detailed soil chemical properties measured in the laboratory inoculation experiment. In this experiment, we extracted soil columns from an arable and secondary woodland and used a third unstructured loamy soil as a control. We sterilized these three soils to remove microbial communities and then inoculated the tops of sterilized soil columns with soil from the secondary woodland or the arable field sites. Control columns of all soil types were not inoculated. In a fully-crossed design, we planted two species possessing distinct root system morphologies: Brachypodium sylvaticum (fibrous system with many thin and fine roots) and Urtica dioica (taproot system with few fine roots). After four months, microbial communities (in bulk and rhizospheric soil) and aggregate stability were measured, along with root traits. In both the field and laboratory experiments, bacterial (16S) and fungal (ITS) diversity was determined using high throughput sequencing.