Microbial Community Traits and Necromass Dynamics Shape Soil Carbon Accumulation.

Area of Science:

• Agricultural Science
• Soil Science
• Microbiology
• Climate Science

Background:

• Soil organic carbon (SOC) is crucial for food security and climate change mitigation.
• Long-term effects of different fertilization strategies on SOC accumulation are not fully understood.
• The Broadbalk Experiment offers a unique, long-term dataset for studying fertilization impacts.

Purpose of the Study:

• To investigate the distinct mechanisms of SOC accumulation under organic versus inorganic fertilization.
• To compare the long-term efficacy of organic and inorganic fertilization for SOC sequestration.
• To elucidate the role of microbial communities and necromass in SOC dynamics.

Main Methods:

• Utilized the 180-year Broadbalk Experiment data.
• Employed 14C labeling and metagenomics to analyze microbial processes.
• Conducted a global meta-analysis of field experiments (0-120 years).

Main Results:

• Organic fertilization increased total SOC by 160% (vs. 26% for inorganic) by enhancing both particulate organic carbon (POC) and mineral-associated organic carbon (MAOC).
• Organic inputs fueled copiotrophic microbes, leading to efficient carbon use and a dual-pathway SOC accumulation.
• Inorganic fertilization promoted an oligotrophic 'mining' strategy, primarily increasing MAOC under carbon limitation.

Conclusions:

• Organic fertilization promotes substantial, time-dependent SOC sequestration through enhanced POC and MAOC.
• Microbial community traits and necromass dynamics are critical for long-term SOC persistence.
• Aligning nutrient inputs with biological mechanisms is key for sustainable carbon sequestration.