Effects of tillage practices on water consumption characteristics and grain yield of winter wheat under different soil moisture conditions

• Top soil that is too loose or too tight led to more water consumption from the topsoil layers.
• Subsoiling increased wheat water consumption from the deep soil layers.
• Moderate topsoil packing and subsoiling increased the yield and WUE.
• The yield-increase effect of harrowing or moderate topsoil packing remained stable.

A serious water shortage is threatening agricultural sustainability in the Huang-Huai-Hai Plain of China. Long-term reduced tillage (shallow rotary tillage) has led to thickening of the plough pan, which prevents the infiltration of precipitation and inhibits the root growth of wheat. Moreover, the topsoil was usually too loose to retain soil moisture. These conditions were not conducive to the highly efficient use of limited water for wheat production. The experiment was conducted from 2011 to 2013 using a split plot design. The main plots contained five different tillage treatments, and the subplots consisted of the two following different irrigation treatments: rain fed and supplemental irrigation (SI). Subsoiling promoted soil water consumption and crop evapotranspiration as well as significantly increased the water potential (ψL), transpiration rate (Tr) and net photosynthesis rate (Pn) of the flag leaves. Furthermore, subsoiling increased the 1000-grain weight and grain yield of winter wheat under both the rain fed and SI conditions compared with long-term rotary tillage. Subsoiling could even increase spike number under SI conditions, but could not increase the agronomic water use efficiency (AWUE). Harrowing or moderate topsoil packing before seeding increased the water content of the topsoil, the water consumption from the deep soil layers, the Pn of the flag leaves, and the 1000-grain weight, grain yield and AWUE in plots that were subsoiled. However, excessive topsoil packing significantly decreased the ψL, Tr, Pn and water use efficiency (WUEleaf) of flag leaves as well as the 1000-grain weight, grain yield and AWUE under both the rain fed and SI conditions.