Field aging slows down biochar-mediated soil carbon dioxide emissions.

Area of Science:

• Soil Science
• Environmental Science
• Biogeochemistry

Background:

• Biochar application is key for soil carbon sequestration, but long-term soil property changes and CO2 emission impacts remain understudied.
• Understanding biochar's transformation in diverse soil types (acidic paddy, alkaline fluvisol) is crucial for effective carbon management.

Purpose of the Study:

• To investigate physicochemical changes in rice and maize biochar after one year of application in paddy and fluvisol soils.
• To evaluate the impact of aged biochar on soil CO2 emissions and carbon sequestration potential in different soil types.

Main Methods:

• Characterization of pristine and aged biochars using SEM-EDS, FTIR, 3D-EEM, and TG-DTG.
• Incubation experiments to measure CO2 emissions from soils amended with aged biochar.
• Statistical analyses including Spearman correlation and PCA to identify key influencing factors.

Main Results:

• One year of soil aging led to consistent biochar property changes: structural degradation, increased surface area, and more oxygen-containing groups.
• Aged biochar showed decreased DOM fluorescence intensity and increased thermal stability.
• Aged biochar reduced cumulative CO2 emissions in both soil types, indicating enhanced short-term carbon sequestration.

Conclusions:

• Field-aged biochar promotes soil carbon sequestration in both acidic and alkaline soils within the short term.
• Reduced DOC release and DOM bioavailability, alongside enhanced humification, are key mechanisms driving aged biochar's impact on CO2 emissions.
• Biochar aging significantly alters its properties, positively influencing soil carbon dynamics.