# Micro-nanobubble oxygenation irrigation ameliorates saline-alkali soil properties, cotton physiology, and yield under different salt stress levels

## TL;DR

Using micro-nanobubble oxygenation irrigation improves saline-alkali soil and boosts cotton growth and yield in arid regions.

## Contribution

Introduces micro-nanobubble oxygenation irrigation as a novel method to rehabilitate saline-alkali soils and enhance cotton productivity.

## Key findings

- MNBs reduced topsoil salinity and mitigated alkalinity stress by leaching salt to deeper layers.
- MNBs increased soil enzyme activity, ionic balance, and microbial diversity, improving soil health.
- MNBs enhanced cotton physiology and yield, with up to 52.31% higher seed cotton yield compared to conventional irrigation.

## Abstract

Addressing soil saline-alkalization is crucial for sustaining cotton production in the arid regions of Xinjiang. This study investigates the efficacy of Micro-Nanobubble oxygenated irrigation (MNBs) compared with conventional flooding (CF) in ameliorating saline-alkali soil and enhancing cotton growth.

A field microplot experiment was conducted across four soil salinity levels (0, 3%, 6%, and 9%, with sulfate as the dominant salt).

The results demonstrated that MNBs effectively reduced topsoil (0~20 cm) salinity and mitigated its associated alkalinity stress by facilitating salt leaching into deeper soil layers (20~60 cm). This irrigation method also significantly improved soil enzyme activities and altered ionic dynamics toward a more favorable balance. Moreover, MNBs enhanced soil bacterial diversity, enriched beneficial phyla such as Proteobacteria and Actinobacteria, and modulated fungal genera including Alternaria and Fusarium, suggesting an improved rhizospheric microbiome. In terms of cotton physiology, Micro-nanobubble oxygenation irrigation significantly enhanced the activities of superoxide dismutase (SOD) and peroxidase (POD) in cotton leaves by 15.84% to 40.69% and 10.11% to 33.63%, respectively, while reducing malondialdehyde (MDA) content by 28.22% to 42.11%, thereby alleviating saline-alkali stress-induced oxidative damage. Additionally, MNBs promoted root growth by 0.96% to 29.90%, increased the leaf area index by 18.68% to 25.50%, and enhanced dry matter accumulation by 6.82% to 33.29%. Ultimately, these improvements led to a higher seed cotton yield. Compared with conventional flooding (CF), the MNBs treatment increased seed cotton yield by 33.78%, 35.93%, 47.11%, and 52.31% across the four salinity levels, respectively.

In conclusion, micro-nanobubble oxygenation irrigation represents an effective strategy for rehabilitating saline-alkali soils and promoting sustainable agricultural development in arid areas.