Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2024 Dec;30(12):e70016.
doi: 10.1111/gcb.70016.

Nitrogen Deposition Weakens Soil Carbon Control of Nitrogen Dynamics Across the Contiguous United States

Affiliations
Free article

Nitrogen Deposition Weakens Soil Carbon Control of Nitrogen Dynamics Across the Contiguous United States

Matthew A Nieland et al. Glob Chang Biol. 2024 Dec.
Free article

Abstract

Anthropogenic nitrogen (N) deposition is unequally distributed across space and time, with inputs to terrestrial ecosystems impacted by industry regulations and variations in human activity. Soil carbon (C) content normally controls the fraction of mineralized N that is nitrified (ƒnitrified), affecting N bioavailability for plants and microbes. However, it is unknown whether N deposition has modified the relationships among soil C, net N mineralization, and net nitrification. To test whether N deposition alters the relationship between soil C and net N transformations, we collected soils from coniferous and deciduous forests, grasslands, and residential yards in 14 regions across the contiguous United States that vary in N deposition rates. We quantified rates of net nitrification and N mineralization, soil chemistry (soil C, N, and pH), and microbial biomass and function (as beta-glucosidase (BG) and N-acetylglucosaminidase (NAG) activity) across these regions. Following expectations, soil C was a driver of ƒnitrified across regions, whereby increasing soil C resulted in a decline in net nitrification and ƒnitrified. The ƒnitrified value increased with lower microbial enzymatic investment in N acquisition (increasing BG:NAG ratio) and lower active microbial biomass, providing some evidence that heterotrophic microbial N demand controls the ammonium pool for nitrifiers. However, higher total N deposition increased ƒnitrified, including for high soil C sites predicted to have low ƒnitrified, which decreased the role of soil C as a predictor of ƒnitrified. Notably, the drop in contemporary atmospheric N deposition rates during the 2020 COVID-19 pandemic did not weaken the effect of N deposition on relationships between soil C and ƒnitrified. Our results suggest that N deposition can disrupt the relationship between soil C and net N transformations, with this change potentially explained by weaker microbial competition for N. Therefore, past N inputs and soil C should be used together to predict N dynamics across terrestrial ecosystems.

Keywords: COVID‐19; air quality; coupled carbon–nitrogen; extracellular enzyme activity; net nitrification; net nitrogen mineralization.

PubMed Disclaimer

References

    1. Aber, J., W. McDowell, K. Nadelhoffer, et al. 1998. “Nitrogen Saturation in Temperate Forest Ecosystems.” Bioscience 48, no. 11: 921–934. https://doi.org/10.2307/1313296.
    1. Ackerman, D., D. B. Millet, and X. Chen. 2019. “Global Estimates of Inorganic Nitrogen Deposition Across Four Decades.” Global Biogeochemical Cycles 33, no. 1: 100–107. https://doi.org/10.1029/2018GB005990.
    1. Ajwa, H. A., C. J. Dell, and C. W. Rice. 1999. “Changes in Enzyme Activities and Microbial Biomass of Tallgrass Prairie Soil as Related to Burning and Nitrogen Fertilization.” Soil Biology and Biochemistry 31, no. 5: 769–777. https://doi.org/10.1016/S0038‐0717(98)00177‐1.
    1. Alfano, V., and S. Ercolano. 2020. “The Efficacy of Lockdown Against COVID‐19: A Cross‐Country Panel Analysis.” Applied Health Economics and Health Policy 18, no. 4: 509–517. https://doi.org/10.1007/s40258‐020‐00596‐3.
    1. Allen, R. G., L. S. Pereira, D. Raes, and M. Smith. 1999. “Crop Evapotranspiration.” Guidelines for Computing Crop Water Requirements (56; FAO Irrigation and Drainage Paper, p. 300). United Nations – FAO.