Soil organic carbon

Soils store vast quantities of carbon and have the potential to help mitigate or exacerbate climate change. We need to better understand the interplay of chemical, physical and biological processes that govern soil carbon cycling and stability.

Dynamic interactions between chemical and biological controls govern the stability of soil organic carbon and drive complex, emergent patterns in soil carbon persistence.

Organic carbon in the top metre of Earth’s soils is far older than previously thought, averaging 4,800 years old. These radiocarbon-derived age estimates require us to recalibrate our expectations of ecosystem gains and losses of carbon.

Soils may accumulate less carbon and with a slower turnover than Earth system models predict, according to analysis of the age distribution of global soil carbon, which finds that the mean age of soil carbon is older than that in simulated in models.

Land management strategies for enhancing soil carbon sequestration need to be tailored to different soil types, depending on how much organic matter is stored in pools of mineral-associated and particulate organic matter, suggests an analysis of soil organic matter across Europe.

Belowground carbon inputs form stable soil carbon more efficiently through microbial formation than carbon addition aboveground, according to soil microcosm experiments that quantitatively compare soil carbon formation efficiencies from different mechanistic pathways.

Soil weathering, rather than short-term warming, controls microbial community composition, nutrient availability and soil carbon content, according to observations from a 3-Myr-old soil chronosequence preserved in river terraces in California.

Coastal vegetated ecosystems have experienced rapid changes in climate and environmental conditions. These changes have caused disturbances to the amount of carbon they store in soils by altering the decomposition process of organic carbon.

Subsidence and carbon emissions in tropical peatlands are primarily linked to drainage history, not land-use type, according to large-scale high-resolution remote sensing in Southeast Asia.

Deep soil carbon in tropical catchments can be rapidly mobilized to rivers upon land-use change to agriculture, suggest analyses of dissolved organic carbon. Such carbon stocks had been thought stable for millennia.

Tropical deforestation induces the loss and transport of old and biolabile soil organic carbon into rivers, suggest analyses of dissolved organic matter in deforested and pristine catchments in the Congo Basin. The mobilized soil carbon is likely to turn into a carbon source.

Deforestation by the ancient Maya led to a destabilization of organic carbon preserved in the underlying soils and reduced the magnitude of the soil carbon sink in this region.

Plant roots in thawing permafrost soils act to enhance microbial decomposition and the loss of soil organic carbon, according to an analysis of observational data and a rhizosphere priming model.

Analyses of inventory models under two climate change projection scenarios suggest that carbon emissions from abrupt thaw of permafrost through ground collapse, erosion and landslides could contribute significantly to the overall permafrost carbon balance.

Permafrost loses carbon at a faster rate than previously thought as climate warms, according to direct soil carbon observations over five years in the field in Alaska’s tundra ecosystem.

Climate feedbacks associated with wetland methane emissions and permafrost-thaw carbon release substantially reduce available carbon budgets to achieve temperature targets, suggest simulations with a climate–land-surface model system.

Warming thaws permafrost, releasing carbon that can cause more warming. Radiocarbon, soil carbon, and remote sensing data suggest that 0.2–2.5 Pg of carbon has been emitted from permafrost as CO₂ and CH₄ around Arctic lakes since the 1950s.