Deep plowing increases soil water storage and wheat yield in a semiarid region of Loess Plateau in China: A simulation study

Context: Rational tillage practice is critical for increasing soil water storage capacity and improving crop production in semiarid areas with uneven rainfall distribution. Objective: The aims of this study are to examine the effects of fallow tillage practice on wheat yield, soil water storage and water use efficiency, to investigate the appropriateness of different tillage practices under varying precipitation conditions, and to identify key factors contributing to yield variations among these practices. Methods: Here we compared the effects of different tillage practices (deep plowing, DP; subsoiling tillage, ST; and shallow rotary tillage, RT) on soil water storage and winter wheat yield in a semiarid region of the Loess Plateau in China, using field experimental data from 2009 to 2014 and APSIM (Agriculture Production System sIMulator) simulation results from 1980-2018. Results: The APSIM well simulated the soil water storage (0-200 cm), phenology, biomass and yield of winter wheat, with R-2 > 0.65 and 0.71 for each variable in calibration years and validation years, and nRMSE <16.9 % and 22.1 %, respectively, indicating a good correlation and medium consistency between simulated and measured values. The simulated average annual soil water storage, biomass, yield, and water use efficiency under DP were 8.4 %, 18.4 %, 25.5 %, and 22.3 % higher than under RT, and 7.9 %, 13.8 %, 22.4 %, and 21.4 % higher than under ST, respectively. These variables did not differ between ST and RT treatments. Compared to RT, DP improved the soil water storage by 9.0 %-12.0 % from October to March, increased by 4.8 %-7.1 % during the fallow period, and increased by 2.5 %-7.4 % from April to June. This was mainly because DP had more precipitation reserves during the fallow period, but in the later stage of wheat growth, as precipitation increased, the difference in soil water storage between different tillage practices decreased. Wheat yield, precipitation and soil water storage were significantly and positively correlated. The difference in yield between DP and RT was greater at the medium than at low and high yield production levels, but that between ST and RT was not significant. Conclusion: DP increased soil water storage from October to March and improved wheat yield, which should be recommended to ensure high wheat yield and efficient water use in the Loess Plateau. Implications: This study validated the applicability of DP tillage in semi-arid areas on a long-term scale and found its superiority at different yield production levels.