Abstract:

【Objective】 Field experiment was conducted to study the effects of tillage on soil temperature and soil thermal properties in winter wheat field. 【Method】 Conventional tillage (CT), rotary tillage (RT) and no tillage with stubble covering (NT) were used from 2004 to 2005 at Luancheng Station of Hebei Province. Soil temperature and thermal properties were measured by thermo-time domain reflectometry. Combining with the growth and development course of winter wheat, tillage effects were discussed. 【Result】 Results showed that the tillage effects on soil temperature were mainly occurred before jointing stage of winter wheat. Compared with CT and RT, NT showed a “higher temperature effect” when temperature was dropping and a “lower temperature effect” when temperature was warming up, significantly. Diurnal average soil temperature was 0.69-1.02 ℃ lower, the seedling and tillering was delayed by 2 and 7 d, tillering time before over-wintering was decreased by 9 d, and the active accumulated temperature was decreased by 54.12-55.55℃?d under NT. During over-wintering stage, NT showed a higher average soil temperature (0.02-0.09℃) and negative accumulated temperature 0.87-2.25℃?d, but the day steadily pass 0℃ was delayed by 7 d, low temperature duration was 2-3 d longer and the revival stage was delayed by 2-6 d. Winter wheat under NT needed more active accumulated temperature 21.54-29.15℃ to complete revival and the jointing stage was delayed by 5 d. The accumulated and diurnal mean temperature difference was decreased by 123.43-148.62℃ and 1.17-1.42℃ under NT, respectively. Compared with CT, the revival was delayed by 4 d, the active accumulated temperature was decreased by 8.55 ℃, and the accumulated temperature difference was increased by 25.19℃. It showed no significant difference of ρc, λ, and α between different tillage systems. 【Conclusion】 In terms of the course of winter wheat, heat use efficiency was the highest under CT and the lowest under NT and the medium under RT. The lower temperature under NT was not beneficial to the growth and development of winter wheat, but beneficial to safe over-wintering. The temperature effects of NT were mainly controlled by stubble covering but not the soil thermal properties.

Key words: tillage, soil temperature, accumulated temperature, temperature difference, thermal properties