Tillage Practices Affected Yield and Water Use Efficiency of Maize (Zea mays L., Longdan No.8) by Regulating Soil Moisture and Temperature in Semi-Arid Environment

Tillage practices can regulate soil environmental factors and, thus, affect crop yield. Farmers' acceptance of this is not high because of a lack of awareness, and, in the dryland farming region of the Longdong Loess Plateau in China, the lack of acceptance is due to the established use of the no-till operation. It is urgent to explore suitable tillage practices for maize (Zea mays L., Longdan No.8) planting in this area. The impact of tillage practices on the soil water content, soil temperature, field water consumption structure, yield, and water use efficiency (WUE) of maize was determined. Six tillage practices were implemented in 2021 and their effects were determined in 2021 and 2022, including conventional tillage with no straw (T), conventional tillage with straw incorporated (TS), subsoiling tillage with no straw (SST), subsoiling tillage with straw incorporated (SSTS), no-tillage with no straw (NT) and no-tillage with straw mulching (NTS). Over two years, compared to T, the soil volumetric water content (SWv) with SSTS was significantly increased in the 5-10 cm soil layer at the V12 (big flare stage of maize) stage in 2022. SSTS significantly reduced soil temperature (ST) in the 20 and 25 cm soil depths at the V12 stage, and in every soil layer of the R2 (grain-filling stage of maize) stage. SSTS significantly reduced soil evaporation during the growing season (Ec), and significantly increased crop transpiration (Tc) when compared to T. Compared with T, SST and SSTS significantly increased biomass yield (BY), by 29.7-32.1 and 41.2-53.5%, respectively, increased grain number per ear by 6.3-16.5 and 10.4-38.8%, respectively, improved grain yield (GY) by 4.9-6.9 and 6.2-13.7%, respectively; SSTS significantly increased WUE by 5.5-15.4%. The correlation between soil volumetric water content at the V12 stage and grain yield was highly significant; the ST at the R2 stage had a significant positive correlation with grain number per ear, GY, and BY. Therefore, subsoiling tillage with straw incorporated increased the soil moisture content and reduced the soil temperature, optimized the water consumption structure, and improved the effective utilization of soil water, resulting in the accumulation of a higher biomass yield, and increased the number of ears, obtaining a higher yield, and improved water use efficiency. Therefore, subsoiling tillage with straw incorporated is a suitable tillage practice in the dry farming area of Longdong Loess Plateau, China.