Soil is a major terrestrial C pool. Nitrogen (N)-induced soil C sequestration has been well documented, however, the underlying mechanisms of how N regulates soil C budgets remain uncertain, which has generated extensive debate about the above and belowground C allocation, in particular under N enrichment.

Researchers led by Dr. KUANG Yuanwen from South China Botanical Garden of Chinese Academy of Sciences and by Dr. LI Jianlong from Nanjing University quantified the responses of soil aggregates and C sequestration to N enrichment in terrestrial ecosystems in China via meta-analysis. They found that N enrichment significantly changed soil aggregation, with macroaggregates and silt-clay fraction being increased and decreased, respectively. Nitrogen enrichment showed greater effects on macroaggregate C than on bulk soil C across all ecosystem, but showed minor ones on microaggregate C and silt-clay C. They suggested that N enrichment promotes particulate organic C accumulation via increasing macroaggregate C and acidifying soils.

The findings highlight that atmospheric N deposition may enhance the formation of soil aggregates and their sequestration of C in terrestrial ecosystems in China. The different changes of soil aggregate C will add greater clarity in predicting soil C pool responses to N deposition, and resolve many competing hypotheses on this topic.

These results were recently published in Global Change Biology, entitled “Nitrogen addition stimulates soil aggregation and enhances carbon storage in terrestrial ecosystems of China: A meta-analysis”.

For further reading, please refer to: https://doi.org/10.1111/gcb.15604.