Straw with different fermentation degrees mediate Se/Cd bioavailability by governing the putative iron reducing...

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Straw returning is a vital agronomic practice with numerous benefits.
• The influence of straw fermentation degree on selenium (Se) and cadmium (Cd) bioavailability remains understudied.
• Understanding these effects is crucial for managing contaminated seleniferous soils.

Purpose of the Study:

• To investigate the impact of different straw fermentation degrees on Se and Cd bioavailability in soil.
• To elucidate the underlying mechanisms, particularly microbial iron reduction.
• To identify key microbial players and soil fractions involved in Se and Cd mobility.

Main Methods:

• Application of straw with varying fermentation degrees to Cd-contaminated seleniferous soil.
• Analysis of Se and Cd bioavailability.
• Linear discriminant analysis effect size (LEfSe) for biomarker identification.
• Network and random forest analyses to determine microbial roles.
• Assessment of iron (Fe) and manganese (Mn) fractions.

Main Results:

• Straw fermentation degree significantly altered Se and Cd bioavailability.
• Original and slightly fermented straw increased microbial iron reduction, enhancing Se and Cd bioavailability.
• Key microbial genera like Ruminiclostrdium and Cellulomonas were identified as biomarkers and implicated in iron reduction.
• Microbial iron reduction negatively affected mineral-associated Se but positively affected mineral-associated Cd.
• Mn fractions showed complex interactions with mineral-associated Se and Cd.

Conclusions:

• Straw fermentation degree is a critical factor controlling Se and Cd mobility in soil.
• The regulation of Ruminiclostrdium and Cellulomonas abundance by straw fermentation influences Fe and Mn fractions.
• These changes in soil fractions ultimately affect Se and Cd bioavailability in contaminated environments.