Soil Carbon Sequestration and Climate Mitigation

Soil carbon sequestration encompasses the capture and long-term storage of atmospheric carbon dioxide in soils, predominantly in the form of soil organic carbon (SOC). Through photosynthetic inputs, plant residues and root exudates introduce organic matter into the soil, where it may be stabilised by physical protection within aggregates, chemical association with minerals or biochemical transformation by soil biota. Enhancing SOC stocks can contribute to climate mitigation by reducing net greenhouse gas concentrations, while simultaneously improving soil structure, water retention and nutrient cycling to support agricultural productivity and ecosystem resilience.

Practices that promote soil carbon accrual include reduced tillage, cover cropping, diverse crop rotations, organic amendments such as compost or biochar, and agroforestry systems. The effectiveness of these measures depends on local soil type, climate, management history and existing SOC levels. Moreover, there are biophysical limits to the rate and magnitude of additional carbon storage, often referred to as saturation thresholds, beyond which soils reach a steady state. Recognising these limits is essential to set realistic mitigation targets and to design regionally tailored strategies.

At a global scale, soil carbon sequestration is regarded as a cost-effective, co-beneficial approach to climate action, capable of delivering negative emissions alongside food security and biodiversity gains. To realise its potential, robust measurement, reporting and verification (MRV) frameworks are required to ensure that claimed SOC increases are genuine, persistent and additional. Policies and incentive structures must incentivise farmers and land managers to adopt and maintain practices that safeguard and build soil carbon over the long term.

Research from Nature Portfolio

Recent studies have employed large-scale meta-analytical approaches to quantify the magnitude and drivers of SOC change under diverse land management scenarios. A comprehensive synthesis of hundreds of meta-analyses spanning tens of thousands of primary studies highlights that land conversion to cropping typically depletes SOC, but that targeted practices—such as integrating trees, applying biochar or using organic amendments—can partially restore stocks and offset losses. Another investigation focused on manure application across global agroecosystems revealed that regular organic amendments can increase SOC by over 30%, with effects varying by climate zone, soil texture and depth, and that combined use of manure and mineral fertiliser often yields the greatest carbon retention.

Soil Carbon Sequestration and Climate Mitigation publication trend

The graph below shows the total number of articles in soil carbon sequestration and climate mitigation across all publications each year (not limited to Nature Index journals).

Technical terms

Soil organic carbon (SOC): The fraction of carbon in soil derived from decomposed plant and microbial biomass, critical for soil fertility and carbon storage.

Carbon sequestration: The process by which carbon dioxide is removed from the atmosphere and stored in a stable form in soil or biomass.

Biochar: A stable, carbon-rich product obtained from anaerobic pyrolysis of biomass, used as a soil amendment to enhance carbon retention and soil properties.

Saturation threshold: The point at which a soil’s capacity to store additional organic carbon is limited by physical or biochemical constraints, leading to diminishing sequestration returns.

Measurement, reporting and verification (MRV): A framework of methods and protocols to quantify, document and ensure the integrity of changes in soil carbon stocks over time.

References

1. Towards a global-scale soil climate mitigation strategy. Nature Communications (2020).
2. Meta-analysis on how manure application changes soil organic carbon storage. Scientific Reports (2021).
3. How to measure, report and verify soil carbon change to realize the potential of soil carbon sequestration for atmospheric greenhouse gas removal. Global Change Biology (2019).
4. Global variation in soil carbon sequestration potential through improved cropland management. Global Change Biology (2021).
5. Carbon for soils, not soils for carbon. Global Change Biology (2023).