Table 1.
Basic physical soil properties of the experimental site.
Fig 1.
Detailed description of different tillage methods.
Table 2.
Details of tillage treatments.
Table 3.
Rainfall precipitation pattern classification table.
Table 4.
Annual rainfall precipitation pattern from 2016 to 2020.
Fig 2.
Effects of tillage cultivation on MWD, GMD, and R0.25 in the 0–40 cm soil layer (2020).
Note: The error bars indicate a significant difference at the P < 0.05 level (two–tailed test).
Fig 3.
Comparison of the effects of straw return on MWD, GMD, and R0.25 under the same tillage cultivations.
Note: S, straw return; NS, straw removal.
Fig 4.
Change in SMCC in each soil layer with different tillage cultivations.
Fig 5.
Effect of straw return on the SMCC of each tillage cultivation in each soil layer.
Fig 6.
Soil specific water capacity of different soil layers under different tillage cultivations at different soil water suction levels.
Note: At the same soil suction, the larger the specific water capacity, the stronger the water supply capacity. NT, no–tillage; SU, subsoiling; RT, rotary tillage; CT, conventional tillage; NTS, no–tillage and straw; SUS, subsoiling and straw; SUS, subsoiling and straw; RTS, rotary tillage and straw; CTS, conventional tillage and straw.
Fig 7.
Variation of SOM in different tillage cultivations and soil layers.
Note: IV, SOM content in 2016; S, SOM content in 2020 with straw return; NS, SOM content in 2020 with straw removal; SC: Straw cover return; NSC: No straw cover return. The left coordinates represent the comparison of SOM content between the starting year of the positioning experiment and after five years of a continuous cultivation. The right coordinates represent different treatments and the increase in SOM compared with the starting year of the positioning experiment.
Fig 8.
Diagram of RUE and yield affected by tillage cultivation.
Note: S, straw return; NS, straw removal. Different capital letters on the error bars indicate significant differences among different tillage cultivations under the same straw treatments (P < 0.05, double tailed test), and different lowercase letters indicate the same tillage cultivation with significant differences under different straw treatments (P < 0.05, double tailed test). No letters on the error bars indicates no significant differences (P > 0.05, double tailed test).
Fig 9.
Pearson’s correlation analysis.
Note: * P < 0.05; ** P < 0.01; *** P < 0.001; (1) means NTS; (2) means SUS; (3) means RTS; (4) means CTS; (5) means NT; (6) means SU; (7) means RT; (8) means CT.MWD, mean weight diameter. GMD, geometric mean diameter. R0.25, >0.25 mm aggregates content. RUE, rainfall utilization efficiency. SOM, soil organic matter. The first column rectangle and its different fillings in the middle indicate different tillage measures and the corresponding eighth column indicator repetition times. Boxplot of second behavior corresponding to tillage and indicator. The lower left is the scatter plot of the corresponding indicator, and the upper right is the correlation coefficient of the two indicators.
Table 5.
Effects of straw residue and tillage interaction on WSAs and SOM at different soil depths.
Table 6.
Effect of straw and tillage interaction on RUE and yield in different year corresponding to rainfall precipitation pattern.