Multidimensional effects and mechanisms of micro-nano bubbles in regulating waterlogged soil microenvironments

Prolonged flooding creates strongly reductive paddy soils that limit nutrient availability and increase greenhouse gas emissions. To address this issue, air and oxygen micro-nano bubbles were evaluated as a low-input amendment in a pot experiment. The oxygen bubbles remodeled soil structure (increased micropores 2.4 times) and raised soil ORP to 374 mV. These changes expanded the abundances of CNP genes, reduced total reducing substances by 22.4%, improved nutrient availability (increased alkali-hydrolyzable nitrogen, available phosphorus and potassium to 216, 72.2 and 284 mg·kg−1, respectively), and lowered the global warming potential by about 26%. Correlation and path analyses indicated that micropore expansion, rather than greater connectivity, plus moderate re-oxidation drove microbial functional gains, nutrient release and methane oxidation. This study offers valuable insights into the multidimensional connection of soil structure, nutrients and soil ecology and it offers a chemical-free route for the green remediation of waterlogged fields.