Tillage-induced effects on SOC through changes in aggregate stability and soil pore structure.

Area of Science:

• Soil Science
• Agronomy
• Environmental Science

Background:

• Soil organic carbon (SOC) dynamics are intrinsically linked to soil structure and aggregate stability.
• Understanding these relationships is crucial for sustainable land management and climate change mitigation.

Purpose of the Study:

• To investigate the impact of conventional tillage (CT) and no tillage (NT) on soil structure, aggregate characteristics, and SOC content in the topsoil (0-5 cm).
• To elucidate the mechanisms by which different tillage practices influence SOC sequestration through soil structural modifications.

Main Methods:

• Undisturbed soil cores were collected from a long-term experimental site in Northeast China under CT and NT treatments.
• SOC content was quantified using elemental analysis.
• Aggregate size distribution was determined by wet sieving.
• Soil pore parameters (pore size distribution, connectivity, anisotropy, fractal dimension) were analyzed using X-ray computed tomography.

Main Results:

• NT significantly increased total SOC (by 26.0%) and aggregate mean weight diameter (by 111.8%), promoting larger aggregate formation (>250 μm).
• CT decreased total SOC but increased aggregate-associated SOC in smaller fractions (<53 μm), while enhancing macropore characteristics and structural anisotropy.
• NT promoted a higher number of micropores and greater pore connectivity, whereas CT favored macropores.

Conclusions:

• Tillage management profoundly influences soil organic carbon dynamics through alterations in soil structure and aggregate formation.
• No tillage enhances SOC sequestration by fostering larger aggregates and improved pore connectivity, while conventional tillage leads to fragmented soil structure and SOC redistribution.
• These findings provide critical insights for optimizing tillage strategies to enhance soil organic carbon storage and improve overall soil health.