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Distinct Biophysical and Chemical Mechanisms Governing Sucrose Mineralization and Soil Organic Carbon Priming in Biochar Amended Soils: Evidence from 10 Years of Field Studies

Summary

This research investigated how adding biochar to agricultural soils affects their long-term carbon storage capacity and soil health. The study found that applying biochar at moderate rates (50-60 tons per hectare) created the best conditions for soil improvement and carbon storage after 10 years. This has important implications for sustainable agriculture and climate change mitigation. Impacts on everyday life: • Helps farmers make better decisions about soil amendments for long-term soil health • Contributes to fighting climate change through improved soil carbon storage • Provides guidance for more sustainable agricultural practices • Demonstrates how to optimize biochar use for better crop growing conditions • Shows potential for reducing agricultural greenhouse gas emissions

Background

While many studies have examined biochar’s role in carbon accrual over short periods, few have explored its decadal-scale influences on non-biochar carbon, such as native soil organic carbon (SOC) and added substrate. Understanding these long-term effects is crucial for evaluating biochar’s potential in soil carbon sequestration and climate-smart agricultural practices.

Objective

To investigate how decade-old biochar field applications affect soil physicochemical properties, microbial communities, and carbon dynamics, specifically examining sucrose mineralization and soil organic carbon priming effects. The study aimed to understand the mechanisms underpinning carbon mineralization and sequestration potential in biochar-amended soils by quantifying native SOC, substrate-derived carbon mineralization patterns, and changes in soil properties.

Results

Soils amended with biochar at medium application rates (50-60 Mg ha−1) showed greater substrate mineralization and improved physicochemical properties including pH, porosity, and pore connectivity. These soils also showed enhanced accessibility of sucrose to microorganisms, particularly fast-growing bacterial genera. However, these same application rates resulted in the lowest priming effect on native SOC, which was associated with increased formation of soil macro-aggregates that protected native SOC.

Conclusion

The study revealed that medium biochar application rates (50-60 Mg ha−1) optimized carbon dynamics by increasing substrate mineralization while minimizing native SOC priming. This was achieved through distinct mechanisms – biophysical factors enhanced substrate accessibility and mineralization, while physicochemical changes protected native SOC through improved aggregation. These findings demonstrate that biochar’s legacy effects persist at least a decade after application.
  • Published in:Biochar,
  • Study Type:Field Trial,
  • Source: 10.1007/s42773-024-00327-0
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