Effects of irrigation-mediated continuously moist and dry-rewetting pattern on soil physicochemical properties, structure and bacterial community

The drying-rewetting cycles (DRW) shaped by climate change are known to affect the physicochemical cycles of natural soils. In irrigated soils, changes in irrigation methods make DRW cycles more repetitive and frequent. However, how irrigation regimes affect the physicochemical properties of irrigated soils and their selection of microbial communities have yet to be discovered. Two irrigation methods for two DRW patterns were selected: (1) continuous irrigation for constantly moist (including three soil wetness, low for CL, medium for CM, and high for CH) and (2) intermittent irrigation for DRW (including three intermittent irrigation frequencies, low for DL, medium for DM and high for DH), to determine the selection of soil physicochemical properties and microbial communities and their effect on yield by mediating soil DRW patterns with different irrigation methods. The results revealed that the DRW pattern mediated by irrigation regimes significantly affected soil physicochemical properties. Constantly moist treatments maintained a more stable soil hydrothermal status, with less soil salinity and slight alkalinity than DRW treatments. The water-stable aggregate was greater in CM, but it was progressively enhanced with increased intermittent frequency. In addition, SOM and TN in CM were 15 %, 25 %, and 35 % higher than in DL, DM, and DH, respectively. High-throughput sequencing results showed that CM had the largest Chao1 index (2610.10), Shannons index (10.23), and Simpsons index (0.9982). The results of the Mental tests indicated that soil moisture patterns exhibited a high degree of explanation by environmental factors. The RDA analysis demonstrated that the PC1 axis (28.7 %) significantly separated the soil bacterial communities of different treatments. These results extend the theoretical understanding of how continuously moist soil and continuous irrigation affect soil physicochemical properties and microbial community diversity. This study provides theoretical guidance for strengthening the application and popularization of continuous irrigation in irrigated soil in the future.