Abstract: Annual rotary tillage can often create a compacted plough pan and shallow arable layer which hampers the high crop yield in Huang-Huai-Hai region. A brand new farming method named Vertically Rotary Tillage was introduced to solve this problem. One short-term field experiment was conducted to explore the effect of deep vertically rotary tillage on soil physical properties and photosynthetic characteristics at flowering stage of winter wheat. Two tillage treatments were designed including subsoiling tillage with 20 cm depth (SS₂₀, CK) and deep vertically rotary tillage with 30 cm depth (DVR₃₀). The result showed that compared with SS₂₀ treatment, DVR₃₀ treatment could thoroughly break the plow pan and loose the arable layer. The soil bulk density at 10-20 cm and 20-30 cm layers under DVR₃₀ treatment was decreased by 9.5% and 11.2% respectively than that under SS₂₀ treatment. Meanwhile, the penetration resistance at 20-30 cm layer under DVR₃₀ treatment was also decreased by 42.3% than that under SS₂₀ treatment. Moreover, water infiltration under DVR₃₀ treatment and the soil water storage in the deep soil layers was then increased. The mass water content of soil increased significantly with the increase of soil depth. There was significant difference of mass water content of 30-40 cm 40-50 cm between SS₂₀ and DVR₃₀. The mass water content 30-40 cm and 40-50 cm layers under DVR₃₀ treatment was increased by 16.9% and 10.6% compared with SS₂₀ treatment, respectively. Furthermore, DVR₃₀ treatment promoted the improvement of the photosynthetic capacity of wheat which could contribute to the dry matter accumulation of winter wheat. The net photosynthesis rate and SPAD at flowering stage of winter wheat leaves under DVR₃₀ treatment were increased by 1.3% and 15.5% respectively than that under SS₂₀ treatment, thereby the above and underground dry matter accumulation of winter wheat under DVR₃₀ was increased significantly. Due to all the superiority of DVR₃₀ treatment over SS₂₀ treatment showed above, the winter wheat yield under DVR₃₀ treatment was increased by 12.4% than that under SS₂₀. It was concluded that deep vertically rotary tillage could provide a new and effective way to break up the compacted plough pan, build a reasonable soil structure and increase crop yield.

Key words: deep vertically rotary tillage, water use efficiency, photosynthetic characteristics, plow pan, penetration resistance