Tuesday, August 4, 2009 - 4:20 PM

COS 37-9: Minor stimulation of soil carbon storage by nitrogen addition

Yiqi Luo1, Meng Lu2, Xuhui Zhou1, Bo Li2, Changming Fang2, and Jiakuan Chen2. (1) The University of Oklahoma, (2) Fudan University

Background/Question/Methods: Anthropogenic nitrogen (N) fertilization and deposition adds 292 Tg N each year, largely to terrestrial ecosystems. N addition usually stimulates biomass growth and results in increases in plant carbon (C) pool sizes. Whether this stimulated biomass growth would lead to increased C storage in soils – the largest pool in the land – is a critical issue for the mitigation of climate change. Fossil fuel burning and deforestation emit about 10 Gt C per year to the atmosphere. Global analysis has shown that terrestrial ecosystems absorb a substantial portion of emitted C. If N addition is one key mechanism underlying contemporary terrestrial C sequestration, the land C sink would be likely to be enhanced as N deposition and fertilization are anticipated to increase in the future. However, impacts of C addition on soil C sequestration remain highly controversial. To reveal a central tendency, we synthesized results from nearly 300 studies using the meta-analysis approach.

Results/Conclusions: Our analysis showed that N addition did not significantly stimulate soil C storage in nonagricultural ecosystems including forests and grasslands but significantly in agricultural ecosystems.  Averaged effects of N addition on soil C storage were minor across all ecosystems. N-induced changes in soil C stocks were significantly regulated by soil C:N. Nitrogen addition tends to stimulate C storage in low C:N soil but increase C loss in high C:N soil. Our results indicate that N stimulation of C storage primarily occurs in plant pools but is highly limited in soil pools.


See more of COS 37 - Biogeochemistry: Atmospheric N Deposition Effects
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See more of The 94th ESA Annual Meeting (August 2 -- 7, 2009)