Soil water use, grain yield and water use efficiency of winter wheat in a long-term study of tillage practices and supplemental irrigation on the North China Plain

We report the results of a six-year study (2007–2013) of tillage regimes for use in producing winter wheat (Jimai 22) on the North China Plain, with supplemental irrigation. The tillage regimes include: plowing for six years (P6); rotary for six years (R6); rotary after subsoiling with an interval of two years (S1R2); subsoiling with an interval of three years (S1R3); subsoiling with an interval of four years (S1R4); and subsoiling with an interval of five years (S1R5). In comparison with the P6 and R6 treatments, the S1R2 and S1R3 treatments improved water storage capacity, maintained higher soil moisture content in the 100–160cm soil layers before sowing and significantly decreased soil moisture content in the 20–180cm soil layers at maturity, in all years. Hence, S1R2 and S1R3 led to greater utilization of water stored in the 60–180cm soil layers. Evapotranspiration (ETc), soil water consumption, and the ratio of soil water consumption to ETc for S1R2 and S1R3 were significantly higher than those for other treatments. Average grain yields for the six growth seasons were ranked as S1R2, S1R3>S1R4>S1R5>P6>R6, while water use efficiency was ranked in the order of S1R2, S1R3, S1R4>S1R5, P6>R6. Grain yields of S1R2 and S1R3 were 9.028 and 8.817kgha−2, respectively, which are higher than the yield of R6 (conventional tillage) by 27.7% and 24.7%, respectively. Hence, rotary tillage after subsoiling with an interval of two or three years (S1R2 and S1R3) can be considered as a desirable tillage practice for increasing yields, while using water efficiently in this region.