Soil carbon availability decouples net nitrogen mineralization and net nitrification across United States Long Term Ecological Research sites

• DOI: 10.1007/s10533-022-01011-w
• Publication Date: 2023-01-10T06:02:58Z
• Authors: A. L. Gill; R. M. Grinder; C. R. See; F. S. Chapin; L. C. DeLancey; M. C. Fisk; P. M. Groffman; T. Harms; S. E. Hobbie; J. D. Knoepp; J. M. H. Knops; M. Mack; P. B. Reich; A. D. Keiser
• Keywords: XXXXXX - Unknown; 0401 agriculture, forestry, and fisheries; 04 agricultural and veterinary sciences

Autotrophic and heterotrophic organisms require resources in stoichiometrically balanced ratios of carbon (C) to nutrients, the demand for which links organismal and ecosystem-level biogeochemical cycles. In soils, the relative availability of C and nitrogen (N) also defines the strength of competition for ammonium between autotrophic nitrifiers and heterotrophic decomposers, which may influence the coupled dynamics between N mineralization and nitrification. Here, we use data from the publicly available US National Science Foundation funded Long Term Ecological Research (LTER) network to evaluate the influence of soil C concentration on the relationship between net nitrification and net N mineralization. We found that soil C availability constrains the fraction of mineralized N that is ultimately nitrified across the continental gradient, contributing to reduced rates of nitrification in soils with high C concentrations. Nitrate, which is produced by nitrification, is a highly mobile ion that easily leaches to aquatic ecosystems or denitrifies into the greenhouse gas nitrous oxide (N2O). Understanding the connection between soil C concentration and soil N transformations is thus important for managing potential ecosystem N losses, understanding the biogeochemical constraints of these losses, and accurately representing coupled C-N dynamics in ecosystem models.