Fancy spectrometry = big insights? What can synchrotron radiation tell us about soils?

Soil is the porous natural body that provides organisms with access to water, mineral and organic energy sources, electron acceptors, nutrients and a structurally diverse physical habitat. Thus the soil segment of the terrestrial biosphere plays a vital role for any organism that is adapted to life on land, including our own species. Whether we are interested in a reliable food supply or in maintaining drinking water quality, the soil 'bioreactor' will be at the heart of respective investigations or management decisions. Consequently, a robust mechanistic knowledge of soil functioning is desirable. Over the past 40 years, advances in analytic instrumentation have changed the concepts that we inherited from the past. Probably the most significant of recent developments in experimental soil research is the new ability to combine spectrometric information with imaging at scales down to the colloidal level, and among the paradigms that have fallen to this new capacity is the old dogma that postulated soil organic matter to consist of recalcitrant, polymeric, highly aromatic "humic substances".

To date, soil research conducted at synchrotrons remains the privilege of teams with the technical and scientific expertise to use radiation with high flux density, short wavelengths, advanced optics and state of the art computation in a synergistic package. The multidisciplinary nature of these teams fosters a new awareness of the need to quantify interdependencies between property (such as 3D soil structure) and process (such as chemical species identification) that is beginning to leave an increasing imprint on soil science. Transformational discoveries will result from research that develops new scaling laws to capture emergent properties of biogeochemically independent but interconnected microenvironments within soils.