Azolla reshapes rhizosphere microbiomes and nutrient cycling in paddy fields

Area of Science:

• Agricultural Science
• Soil Science
• Microbiology

Background:

• Soil quality is crucial for agricultural productivity and sustainability.
• Azolla's symbiotic nitrogen fixation can improve soil quality, but its role in paddy systems needs further characterization.
• Understanding Azolla's impact on nutrient cycling and microbial communities is essential.

Purpose of the Study:

• To elucidate the effects of Azolla on soil quality in paddy systems.
• To examine Azolla's impact on nutrient cycling dynamics and microbial community composition.
• To uncover the interactions between soil properties and microbial communities under Azolla application.

Main Methods:

• Integrated soil physicochemical analyses, enzyme activity assays, and bacterial community profiling.
• Co-occurrence network analysis and correlation assessments were employed.
• Comparison between rice monoculture (R) and rice-Azolla co-cultivation (RA) systems.

Main Results:

• Rice-Azolla co-cultivation (RA) significantly increased carbon- and nitrogen-cycle enzyme activities (3-44%) but decreased phosphorus-cycle enzyme activities (12-42%).
• Azolla altered bacterial community structure and reduced alpha diversity under high nitrogen fertilization.
• Specific taxa, including Haliangium and Sphingomonas, were recruited in the RA system with higher relative abundances.

Conclusions:

• Azolla application enhances soil quality by increasing nutrient content and promoting microbe-mediated nutrient recycling.
• The study reveals mechanisms by which Azolla improves soil properties through interactions with microbial communities.
• Azolla shows potential as a sustainable biofertilizer for agricultural soil enhancement, offering an alternative to conventional fertilization.