Nitrogen deposition does not alter the temperate forest soil carbon pool: A 14-y experiment on varied nitrogen fertilization.

Nitrogen deposition over 14 years does not alter soil carbon pools in nitrogen-limited temperate forests, despite increases from organic and inorganic N individually.

• Why it matters: Understanding how long-term nitrogen inputs influence soil carbon is vital for predicting global carbon cycle responses, especially in nitrogen-limited ecosystems where data are scarce.
• What they did: A 14-year experiment applied 100 kg N ha -1 y -1 with a mix of inorganic and organic N forms, measuring effects on soil carbon pools, pH, and organic carbon fractions.
• The result: While overall soil C pools remained unaffected, organic N increased soil C by 2.7-fold and inorganic N by 1.8-fold individually; organic N also enhanced mineral-associated organic C, suggesting increased C stability.