Ruminating on soil carbon: Applying current understanding to inform grazing management

Area of Science:

• Agricultural Science
• Soil Science
• Climate Science

Background:

• Soil organic carbon (SOC) sequestration via grazing management is a promising climate change mitigation strategy.
• A clear understanding of how grazing influences SOC stocks and their distribution (particulate vs. mineral-associated organic matter) across diverse climates is lacking.
• Existing research on grazing and SOC lacks a cohesive framework, hindering effective on-the-ground management decisions.

Purpose of the Study:

• To review the effects of grazing management on SOC sequestration.
• To develop a unified conceptual framework integrating plant ecophysiology and soil biogeochemistry to explain SOC dynamics under grazing.
• To inform grazingland managers on optimizing SOC sequestration through management practices.

Main Methods:

• Literature review synthesizing decades of research on grazing and SOC.
• Application of a conceptual framework considering plant productivity, input quality, soil mineralogy, and climate (aridity).
• Analysis of how grazing management levers (timing, intensity, duration, frequency) influence SOC pathways.

Main Results:

• Grazing management significantly impacts SOC stocks and their partitioning into particulate (POM) and mineral-associated organic matter (MAOM).
• Plant ecophysiology and soil biogeochemistry, influenced by climate and soil properties, co-govern SOC accumulation and stabilization.
• Management levers offer pathways to optimize SOC sequestration.

Conclusions:

• A unified framework is essential for understanding and predicting grazing management's impact on SOC sequestration.
• Optimizing grazing patterns can enhance SOC sequestration, contributing to climate change mitigation.
• Further research is needed to address measurement challenges and refine management strategies for maximizing SOC sequestration.