Yecheng Zhang，Fiston Bizimana，Kun Han，Xiaohan Duan，Shaobo Wang，Jingyi Shao，Xinkun Liu，Qisong Gao，Xianfeng Zhang，Keqiang Li，Ling Liu，Huifang Han 

Abstract

The physico-chemical mechanisms underlying the effect of tillage on soil organic carbon (SOC) sequestration are not fully understood, especially those involving soil macropores and iron-aluminum (Fe-Al) oxides. A long-term field experimental setup from 2002 was carried out to investigate the effects of two tillage practices (subsoiling, SS, and rotary tillage, RT) on macropore system, Fe-Al oxides distribution, aggregate stability and SOC sequestration. Soil macropores were evaluated by X-ray computed tomography. Results showed that SS increased 10–40 cm soil profile total macroporosity, especially > 2000 µm macroporosity (33.9–191.3 %), surface area (67.8–100.9 %), volume (51.6–127.6 %), and fractal dimension (3.3–6.4 %), as compared with RT. SS also improved pore throat parameters (coordination number, length, radius, and volume) in 20–40 cm soil depth. Consequently, the proportion of 20–40 mean weight diameter (MWD) of SS increased by 12.4 % as compared with RT. Compared to RT, SS also increased the free Fe-oxides, free Al-oxides, complex Fe-oxides, and complex Al-oxides by 8.3–10.7 %, 14.0–24.3 %, 8.8–13.8 %, and 7.8–11.0 %, respectively, which play a crucial role in stabilizing SOC. Mantel analysis showed macropore parameters (>2000 µm macropore, surface area and volume), pore throat parameters (length, volume) and Fe-Al oxides exhibited strong correlations with SOC (p < 0.01). Consequently, SS increased 20–40 cm SOC content by 24.4 % and 0–40 cm soil profile SOC stocks by 18.7 %. Our study demonstrates that SS concurrently optimizes soil physical architecture and enriches reactive mineral phases. These findings provide a basis for understanding the coupled biogeochemical and biophysical processes driving SOC persistence, offering empirical support for SS as a climate-smart agricultural practice.

Paper Linkage:https://doi.org/10.1016/j.still.2026.107132