Effects of mechanical tillage years on soil physical properties of fluvo-aquic paddy soil

Agricultural mechanization and farming methods are important factors that cause the change of soil physical properties of cultivated land. It is of great significance to explore the variation characteristics of soil physical properties in the fluvial paddy soil area of the Jianghan Plain under different mechanized tillage years, so as to clarify the change trend of regional soil quality, reasonably improve the soil structure of the regional tillage layer, select suitable tillage measures, and further increase crop yield and efficiency. In this study, the interannual variation characteristics and trends of soil physical properties of double cropping rice planting patterns under different tillage years were simulated and analyzed by in-situ simulated tillage experiments in the fluvial paddy soil of the Jianghan Plain. The results showed that: 1) The soil moisture index decreased with the extension of mechanical tillage years, and the soil layer below the plough bottom layer (20−40 cm) was generally stable, and the 30−40 cm layer had a slow increasing trend. 2) Under the action of long-term mechanical tillage, the soil structure stability gradually decreased with the extension of tillage years, and the fragmentation rate of soil aggregate structure increased with the deepening of the profile, and the stability of soil structure decreased. The soil compactness increased greatly with the deepening of the profile and then tended to decrease slowly, which was related to the thickening and upward movement of the plough bottom caused by long-term mechanical operation. 3) Under long-term mechanical tillage, the soil compression capacity generally increased first and then decreased slowly. The early consolidation pressure showed a decreasing trend in the bottom layer of the plough (10−20 cm), while the soil in the lower layer of 20−40 cm showed an increasing trend, indicating that soil bulk density and water content were the key factors affecting the maximum compressive capacity of soil. The results of this study can provide parameter support and theoretical basis for the improvement of soil quality in rice planting areas of Jianghan Plain.