Exploring the limits of mineral- associated organic carbon formation in temperate soils

verfasst von

Neha Begill

betreut von

Georg Guggenberger

Abstract

Soils store almost three times more organic carbon (OC) than the atmosphere. This makes the sequestration of soil organic carbon (SOC) a promising strategy for mitigating climate change. SOC can be divided into particulate organic carbon (POC) and mineral-associated organic carbon (MAOC). POC is more susceptible to decomposition by microorganisms because it is not bound to mineral surfaces and therefore breaks down more rapidly. In contrast, MAOC is more stable, persisting for decades to centuries due to its strong associations with mineral particles. This longevity makes MAOC a key target for SOC sequestration. According to the concept of SOC saturation concept, the ability of a soil to store additional MAOC is limited by its silt and clay content, beyond which additional C is less protected. Soils with a lower SOC content have a higher sequestration potential due to a larger SOC saturation deficit, i.e., the difference between the current and the maximum MAOC storage capacity. In this dissertation, the potential limitations of the SOC saturation concept are critically analyzed using three complementary studies. The first study found no evidence of an upper limit for MAOC storage in different soils. The second study confirmed that soils stabilize OC even beyond theoretical saturation limits. The third study showed that the efficiency of MAOC formation remained constant despite increasing carbon inputs in both the topsoil and subsoil. These results challenge the existing concept of SOC saturation as they show that SOC stabilization is determined by sustained carbon inputs and not by mineral limitations. These results emphasize the untapped potential for long-term SOC sequestration and the need to prioritize C input from agricultural management in the context of climate change adaptation.

Organisationseinheit(en)

Abteilung Bodenkunde

Typ

Dissertation

Anzahl der Seiten

126

Publikationsdatum

17.07.2025

Publikationsstatus

Veröffentlicht

Ziele für nachhaltige Entwicklung

SDG 2 – Kein Hunger, SDG 13 – Klimaschutzmaßnahmen

Elektronische Version(en)

https://doi.org/10.15488/19251 (Zugang: Offen)