This study investigates the impact of root inputs on soil carbon and the net changes in topsoil and subsoil carbon pools. Using a 20-year chronosequence of deeply inverted grassland soils in New Zealand, the researchers used fresh and isotopically labeled roots to track the source of respired carbon and soil carbon fractions. They found that fresh roots stimulated microbial decomposition of existing humus, but this effect was temporary and decreased over time. The adaptation effect, which persists in topsoil material buried in the subsoil for only a few years, suggests that the stability of organic matter in the subsoil is dependent on the input of fresh roots as a source of carbon and energy. The study also found that the input of new roots has never resulted in net soil carbon losses, suggesting a means of carbon sequestration in topsoil and subsoil.
Schiedung, M., Don, A., Beare, M. H., Abiven, S.: Soil carbon losses due to priming moderated by adaptation and legacy effects. Nature Geoscience (2023)