Impact of Subsoiling on Cultivated Horizon Construction and Grain Yield of Winter Wheat in the North China Plain

In order to explore the effects of subsoiling tillage measures on the construction of soil cultivated horizon and the yield and water use efficiency of winter wheat in the North China Plain, three tillage methods, including no tillage (PZ), rotary tillage (PR), and subsoiling (PS), combined with straw returning measures were implemented in the winter wheat season in Xinxiang, Henan Province from 2016 to 2018. The effects of tillage measures on the improvement of cultivated land quality and the water saving and yield increase of winter wheat were investigated. The results showed that compared with no-tillage treatment, subsoiling significantly reduced soil bulk density by 8.88% and increased soil porosity by 13.04% in 20-40 cm soil layer; significantly reduced soil compaction by 56.96% in 0-40 cm soil layer; subsoiling combined with straw returning significantly increased soil organic carbon content in plough layer of winter wheat, whereas rotary tillage decreased soil organic carbon content. Subsoiling is more conducive to soil moisture movement to the deep layer after irrigation or rainfall, and the water consumption of subsoiling is the largest in the whole growth period of winter wheat. Subsoiling could better coordinate the relationship between water consumption and yield, which increased yield by 34.48-38.10% and water use efficiency by 19.57-21.96% compared with no-tillage treatment, respectively. Therefore, subsoiling before sowing combined with straw returning was beneficial to the reasonable construction of soil cultivated horizon, and significantly improved the yield and water use efficiency of winter wheat under the climatic conditions in the North China Plain.