Abstract: This research was aimed at the development of high-yield and high-efficiency tillage techniques for the production of rain-fed forage maize in semi-arid areas of China. A long-term (2017-2019) field experiment consisting of three treatments: traditional tillage (TT), deep tillage (DT), and vertical rotary sub-soiling tillage (VRT), was carried out in the Loess Plateau, Northwest China. VRT is a recently developed tillage technique designed to break up the compacted soil layer formed just beneath the cultivated layer after repeated cycles of annual rotary tillage. We had investigated the effects of VRT on soil water storage (SWS), crop evapotranspiration (ETc) before and after anthesis, fresh and dry weights per plant, grain yields as well as water use efficiency (WUE). It was found that VRT significantly improved the infiltration of soil moisture to deeper layers, especially in dry years. At the anthesis stage, VRT decreased SWS by 7.6%-10.0% in 60-180 cm layer, and by 17.6%-18.5% in the 180-300 cm layer, compared to DT and TT in the dry year. Prior to the anthesis, SWS of VRT was increased by 13.8%-14.6% in the 0-300 cm layer, and the total ETc of VRT was increased by 6.1%-9.2%, respectively. Compared with DT and TT, VRT increased total ETc by 2.0%-7.9% in 2018, and by 10.1%-14.9% in 2019. At harvest, VRT increased fresh weights per plant by 2.4%-16.2%, dry weights per plant by 1.0%-7.8%, grain yields by 2.4%-38.6%, and population biomass by 3.4%-16.2%. It can be concluded that VRT is a drought-resistant and yield-enhancing tillage technique that is suitable for rain-fed forage maize production in semi-arid areas of the Loess Plateau. The data indicate VRT, improves the soil environment and enhances crop growth, development and yield. The benefits of VRT are more pronounced in dry years.

Key words: vertically rotary sub-soiling, soil moisture, yield, water use efficiency, forage maize, semiarid land