Perspectives from the Fritz-Scheffer Awardee 2021: Soil organic matter storage and functions determined by patchy and piled-up arrangements at the microscale

Abstract

Mounting evidence of recent spectromicroscopic insights have revealed that the distribution of mineral-associated organic matter (OM) at the microscale and nanoscale is organized heterogeneously in patchy and piled-up arrangements of varying thickness. Spectromicroscopic approaches could show local deterministic features of distinct OM and mineral composition that influence the heterogeneous lateral OM distribution. OM–OM interactions shape vertical and three-dimensional OM structures with potentially multilayered composition. Conceptualizing mineral-associated OM as patchy-distributed and piled-up has critical implications for our understanding of soil ecosystem functions as it defines their functional properties in compartmentalized regions at the microscale and nanoscale. The concentrated storage of OM associated to only a minor part of mineral surfaces implies that carbon sequestration may be decoupled from a direct limitation by the amount of fine mineral particles while sustaining mineral surface functionality in other parts. At the microscale and nanoscale, differences in altered surface properties, compartmentalized microhabitats, and biotic architectures shape a conceptual understanding where OM storage and other soil functions are driven by spatially resolved interactions. This novel conceptual framework warrants experimental approaches to incorporate the patchy and piled-up arrangement of OM and upscale potential effects of its heterogeneous arrangement to systematically understand the effectiveness of soil functions.