Towards an ecosystem capacity to stabilise organic carbon in soils.

Soil organic carbon (SOC) accrual, and particularly the formation of fine fraction carbon (OC), has a large potential to act as sink for atmospheric CO. For reliable estimates of this potential and efficient policy advice, the major limiting factors for OC accrual need to be understood. The upper boundary of the correlation between fine mineral particles (silt + clay) and OC is widely used to estimate the maximum mineralogical capacity of soils to store OC, suggesting that mineral surfaces get C saturated.

Root litter quality drives the dynamic of native mineral-associated organic carbon in a temperate agricultural soil.

Background And Aims: Understanding the fate and residence time of organic matter added to soils, and its effect on native soil organic carbon (SOC) mineralisation is key for developing efficient SOC sequestration strategies. Here, the effect of litter quality, particularly the carbon-to-nitrogen (C:N) ratio, on the dynamics of particulate (POC) and mineral-associated organic carbon (MAOC) were studied.

Methods: In a two-year incubation experiment, root litter samples of the C4-grass with four different C:N ratios ranging from 50 to 124 were added to a loamy agricultural topsoil.

Response to: "The robust concept of mineral-associated organic matter saturation: A letter to Begill et al. (2023)".

In this response to a letter to the editor, we provide evidence that the findings regarding a non-detectable limit of mineral-associated organic carbon as published in Begill et al. (2023) are robust. This is mainly done by showing that no methodological bias was present and that the main correlation was not driven by a few exceptional soils.

No detectable upper limit of mineral-associated organic carbon in temperate agricultural soils.

Soil organic carbon (SOC) sequestration is a promising climate change mitigation option. In this context, the formation of the relatively long-lived mineral-associated organic carbon (MAOC) is key. To date, soils are considered to be limited in their ability to accumulate MAOC, mainly by the amount of clay and silt particles present.