Converting continuous cropping to rotation including subsoiling improves crop yield and prevents soil water deficit: A 12-yr in-situ study in the Loess Plateau, China

Water deficit and conventional production mode limited agriculture sustainable development on the Loess Plateau. Crop rotation and conservation tillage appears to serve as an effective strategy to optimize water resources distribution and utilization. From 2007–2019, a 12-yr in-situ experiment consisting of three cropping systems (winter wheat continuous cropping, WW; winter wheat-spring maize rotation, WM; spring maize continuous cropping, MM) and two tillage methods (conservation tillage, subsoiling, ST; conventional tillage, plowing, CT) were conducted in a semi-arid region, and grain yield, economic profit, water use, precipitation storage and loss, soil water balance were analyzed to explore the mechanism and potential of crop rotation and conservation tillage regulating soil water balance and increasing farmland productivity. Our results show that compared to WW, WM and MM significantly enhanced grain yield by 4358 and 8791 kg ha−1 in 2-yr rotation cycle, respectively. And ST increased grain yield after 3 cycles with 979 kg ha−1. WM and MM with ST significantly reduced precipitation loss (78 and 135 mm) during the fallow period, and increased WUE (6.5 and 10.8 kg ha−1 mm−1), compared to WW-CT. With the passage of time, soil water storage of WW and MM showed a decreasing trend in 100–200 and 0–100 cm layers compared to pre-experiment, with the rate of 18.1 and 13.6 mm per cycle. And ST could ease the downward trend, relative to CT. However, the WM-ST maintained soil water balance by regulating water use and precipitation storage, compared to the two continuous cropping systems. Additionally, correlation analysis showed that evapotranspiration was positive to soil water balance and we should consider crop water use when designing cropping system to prevent soil water deficit. Overall, the WM-ST achieved better soil water sustainability, on the basis of sacrificing grain yield partly (4646 kg ha−1 in 2-yr rotation cycle) compared to MM-ST, which perhaps more eco-friendly and sustainable agricultural technique to replace WW-CT in the Loess Plateau of China.