Effects of subsoiling rotational patterns with residue return systems on soil properties, water use and maize yield on the semiarid Loess Plateau

In recent years, conservation rotational tillage has been proposed to regulate soil physicochemical properties and improve soil productivity. However, the response of soil productivity to different rotational tillage with residue return systems remains unclear. Based on this concept, a long-term experiment (2007-2019) concerning conservation rotational tillage with residue-returned was established with four tillage treatments: (1) no-tillage was set at the first year, conventional tillage was set at the second year, and the third year was set with subsoiling (NCS); (2) the first year was set with no-tillage then rotated with subsoiling in the second year (NS); (3) the first year was set with subsoiling then rotated with conventional tillage in the second year (SC); (4) subsoiling (S) was set each year as the control, and all tillage took place after the residue return. After a 12-year in situ tillage experiment, NCS and SC significantly reduced soil bulk density (BD) by 7.4 % and 13.2 %, respectively, and increased soil porosity by 8.8 % and 14.6 %, respectively, in the 0-20 cm soil depth. Meanwhile, NCS, NS and SC increased the macroaggregates by 27.4 %, 22.4 % and 30.0 %, respectively, at the 0-40 cm soil depth, and NCS significantly increased aggregate stability compared with S. For the effect of different tillage practices on soil nutrients, SC slight increased annual average soil organic (SOC) and total nitrogen (TN) by 4.5 % and 7.2 % compared with S. In addition, the soil water balance showed a negative trend of consumption, but NCS, NS and SC mitigated water consumption at the 0-200 cm soil depth, especially in dry years. The 12-year spring maize cultivation consumed soil water storage at a 120-420 cm soil depth, especially in ST, which increased this factor by 28.7 %-34.1 % when compared with others. In normal year, NCS significantly increased yield by 3.7 %-10.4 % compared with others. Considering the effect of the long-term experiment, NCS increased the annual average yield, WUE and PUE by 5.2 %, 4.7 % and 5.6 % compared with S, respectively. Based on the comprehensive Zindex score, the NCS with residue return was selected as the recommended agricultural management measure suitable for the climate-similar region of the Loess Plateau.