Abstract: 【Objective】The objective of this experiment is to explore the water-saving and yield-increasing effect of sub-soiling tillage in wheat field in canal irrigation regions, and aim to increase the yield potential and the water storage capacity.【Method】Using Liangxing 99, a winter wheat cultivar currently cultivated in Haihe low land plain as material, three tillage treatments including rotary tillage (RT), sub-soiling tillage (SRT), and moldboard plow tillage (MRT) were set up in a field experiment in canal irrigation region of Haihe lowland plain during 2011-2012 and 2012-2013. 【Result】 Sub-soiling tillage improved the soil water infiltration rate, in which the soil water infiltration rate of SRT treatment was 0.05 mm·s^-1 that was 2.50 and 1.67 folds of those in RT treatment and MRT treatment, respectively. Sub-soiling tillage was conducive to infiltration of the irrigated water in the soil, in favour of the water distribution in deep soil, and improvement of the storage capacity of surface water effectively. After 48 h of irrigation, the soil water storage content in SRT treatment was 158.5 mm in 0-180 cm soil layer, where it was 142.5 mm and 144.1 mm in the RT and MRT treatments, respectively. They were equivalent to that of 89.9% and 90.9% of the SRT treatment. Before wintering stage, the evaporation rate was the highest in MRT treatment, which was 1.15 and 1.35 times higher than the treatments of SRT and RT, respectively. After regreening stage, the evaporation rate in RT treatment was increased, and gradually increased to the date of spring irrigation with a value of 1.32 mm·d^-1. However, the evaporation rate in treatments of SRT and MRT were low, with values of 0.78 mm·d^-1and 0.85 mm·d^-1, respectively. The evaporation amount was the lowest in the SRT treatment (138.17 mm), which was equivalent to 86.9% and 89.7% of RT and NRT, respectively. The water storage content in 0-100 cm soil layer in RT treatment was more than those in SRT and MRT treatments from sowing date to jointing stage. Further analyses indicated that RT treatment had the highest water storage content in 0-20 cm soil layer, whereas SRT treatment had the highest water storage content in 20-80 cm soil layer. There were no significant differences in water storage content under the soil layer below the 80 cm layer among the three treatments. The total water consumption in SRT treatment was 419.1 mm across the whole growth stage, which saved water by about 6% in comparison with the treatments of RT and MRT. Of which, the consumption ratio of irrigation to precipitation in SRT treatment was 41.2% and 22.0%, respectively, which was significantly higher than those in MRT and RT treatments. The average yield in SRT treatment was 8 550 kg·hm^-2 across the two growing seasons. It had increases of 15.4% and 6.9% compared with those in treatments of RT and MRT, respectively. Moreover, the water use efficiency in SRT treatment increased by 22.9% and 14.0% compared with those in treatments of RT and MRT, respectively. 【Conclusion】 Sub-soiling tillage improved soil water infiltration rate, decreased the evaporation amount of irrigation and precipitation, and reduced the water consumption in winter wheat field. This tillage method could increase the water use efficiency and irrigation productivity efficiency and yield. Accordingly, sub-soiling tillage practice is recommended in winter wheat production in canal irrigation regions in Haihe lowland plain.

Key words: Haihe lowland plain, canal irrigation district, sub-soiling, wheat field, water-saving and yield-increasing effects