Objective  The hydrothermal dynamics of soil at sugarcane fields in Guangxi province was studied under different tillage methods to provide information for effective utilization of the natural resource.

  Method  The moisture content and temperature of soil in the depths of 5, 20 and 40 cm under two tillage methods were monitored. Smash-ridging tillage (T) and no-tillage (NT) were applied in the sugarcane field at Lijian Research Station of Guangxi Academy of Agricultural Sciences in Nanning. In addition to the basic properties, the temperature, thermal conductivity, and heat flux of the soil under the treatments were collected for analysis.

  Result  The texture of the NT-treated soil invariably affected the temperature distribution at different depths to show it from high to low in the order of 5 cm > 40 cm > 20 cm with significant differences at P < 0.05 (same level for the following). Whereas, when T was applied the texture was altered to cause the temperature ranking changed to 5 cm > 20 cm > 40 cm. During the time of this study, the thermal conductivity of the 5 cm and 20 cm soil under the T treatment was higher than that under NT. Compared to NT, T provided advantages on the infiltration, storage, and improved water distribution in the soil, leveling the thermal conductivities in various layers. Furthermore, varied precipitation significantly affected the heat flux in the 5-20 cm layer under NT more than T but less in the 20-40 cm layer. It indicated that the heat flux in the T-treated soil decreased gradually from the top to the deeper layers. On the other hand, in the NT-treated soil, it fluctuated greatly between the upper and lower layers with varied rain falls.

  Conclusion  The smash-ridging tillage improved the texture and temperature distribution of the soil in the tested range with a more constant and predictable thermal conductivity and heat flux over no-tillage method.