| To investigate the impact of different tillage practices on organic and inorganic carbon in farmland soils in arid regions and to provide theoretical support for optimizing soil aggregate carbon sequestration under conservation tillage. Based on the spring corn field experiment established in 2022, four tillage treatments were set up: bare sowing (BT), mulching (CT), no-till (NT), and shallow tillage (ST). The distribution characteristics of organic carbon (SOC) and inorganic carbon (SIC) in aggregates were measured in the 0-20 cm, 20-40 cm, and 40-60 cm soil layers. The results show that: 1. In the 1.0-20 cm soil layer, the proportion of aggregates>2 mm increased by 2.1% and 24.7%, respectively, compared to bare sowing under no-till and shallow tillage. The proportion of aggregates <0.25 mm decreased by 1.2%,0.8%, and 96.4%, respectively, compared to bare sowing under mulching, no-till, and shallow tillage. No significant differences were observed in other treatments. 2. Under NT and ST treatments, the average content of organic carbon in aggregates>2 mm increased by 81.3% and 132.2%, respectively, compared to BT. The average content of organic carbon in aggregates 1-2 mm increased by 43.5% and 77.5%, respectively, compared to BT. Organic carbon in soil aggregates is mainly concentrated in the>2 mm size fraction. The content of organic carbon in soil aggregates under mulching decreased by 21.3% to 45.5% with increasing planting years. The content of organic carbon in all treatments showed a downward trend with increasing soil depth. 3. The content of inorganic carbon in soil under mulching decreased by 22.3% in 2024 compared to 2022, and was significantly higher than BT treatment in 2023-2024, reaching 206. 3%-281.8% (P<0.05) The inorganic carbon content of soil aggregates showed no significant difference across different particle sizes; under the same treatment, the inorganic carbon content increased with depth in the soil layer. In 2024, compared to 2022, bare sowing, mulching, no-till, and shallow tillage treatments reduced the inorganic carbon content by 36.4%-42.3%,15.1%-22.3%,28.2%-31.9%, and 11.0%-25.6%, respectively. In 2024, within the 0-60 cm soil layer, the shallow tillage treatment increased the average weight diameter (MWD) and geometric mean diameter (GMD) by 8.6%-17.9%,12.5%-32.8%, and 8.6%-17.9%, respectively, compared to the other three treatments. Compared to the MWD, it also increased by 5.7%-11.6%,7.5%-16.9%, and 5.9%-11.6%, respectively. As the planting years increased, the ST treatment showed an increasing trend in both the average weight diameter (MWD) and geometric mean diameter (GMD). Shallow tillage treatment helps enhance soil organic carbon content and exhibits better soil aggregate stability and accumulation of aggregate organic carbon compared to other treatments. |