Volume 1 (2025) 

The mechanisms of soil aggregate size distribution affecting pore structure characteristics and organic carbon mineralization

Yueming Cheng, Bo Tang, Limin Duan

Volume 1 (2025), Article ID: eip1v0730a 

Published: 2025-07-30 (Received: 2025-04-10; Revised: 2025-07-12; Accepted: 2025-07-28)

DOI:  https://doi.org/10.5281/zenodo.16623757     

Citation

Cheng Y, Tang B, Duan L. The mechanisms of soil aggregate size distribution affecting pore structure characteristics and organic carbon mineralization. Engineering Innovation and Practice, 2025, 1, eip1v0730a.

Abstract

Soil aggregates are the fundamental structural units of soil, and their size distribution plays a crucial role in shaping the soil pore structure characteristics and regulating organic carbon mineralization processes. This study, conducted on farmland soils from Sichuan Province, employed sieving methods to obtain aggregates of different size fractions (>5 mm, 2–5 mm, <0.5 mm), combined with X-ray micro-CT technology and laboratory incubation experiments, to systematically investigate the mechanisms by which aggregate size distribution affects soil pore structure and organic carbon mineralization. The results showed that small-sized aggregates (<0.5 mm) significantly reduced macroporosity (>16 μm) by 83.2%–93.6% and pore connectivity by over 95%. Moreover, small-sized aggregates significantly enhanced soil organic carbon mineralization, with cumulative mineralization increasing by 64.3%, 79.7%, and 14.5% in the control, low organic fertilizer, and high organic fertilizer treatments, respectively. Correlation analysis revealed a significant positive relationship between cumulative mineralization and porosity in the 16–30 μm range. Mechanistic analysis indicated that aggregate breakdown released physically protected organic carbon and altered pore structures, thereby influencing microbial activity and carbon metabolic pathways. Additionally, different levels of organic fertilizer application significantly regulated the effects of aggregate size distribution on carbon mineralization, with the high organic fertilizer treatment exhibiting the most pronounced impact. This study elucidates the coupling mechanisms between aggregates, pore structure, and organic carbon mineralization, providing practical insights for optimizing soil carbon management and enhancing carbon use efficiency in agricultural ecosystems.

Keywords

soil aggregates, organic carbon mineralization, pore structure, aggregate size distribution, organic fertilizer

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