Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition

Lang C. DeLancey; Qian Zhao; Adrienne B. Keller; Christopher A. Walter; Kirsten S. Hofmockel; Melanie A. Mayes; Eric W. Seabloom; Elizabeth T. Borer; Andrew D.B. Leakey; Sarah E. Hobbie

doi:10.1016/j.soilbio.2025.110000

Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition

Lang C. DeLancey
, Qian Zhao
, Adrienne B. Keller
, Christopher A. Walter
, Kirsten S. Hofmockel
, Melanie A. Mayes
, Eric W. Seabloom
, Elizabeth T. Borer
, Andrew D.B. Leakey
, Sarah E. Hobbie

Ecosystem Processes

Research output: Contribution to journal › Article › peer-review

Abstract

Previous work has found that anthropogenic inputs of nitrogen (N) and phosphorus (P) impact heterotrophic respiration during soil organic matter decomposition in grasslands, a critical pathway through which carbon (C) is lost from soil to the atmosphere. While N addition typically reduces heterotrophic respiration, why the strength and direction of this N effect varies among sites is unclear. To address this, we conducted a 339-day laboratory incubation to measure heterotrophic respiration from nine grasslands across North America that have received 10 years of factorial N and P fertilization. N addition reduced cumulative respiration most at sites with low pH, low microbial allocation towards N acquisition, and high soil C concentration and availability. However, N addition had neutral rather than positive effects on heterotrophic respiration in sites with high pH and decomposer allocation towards N acquisition. Across sites, a decade of N addition reduced heterotrophic respiration by ∼24 %, driven by reductions in microbial biomass. Heterotrophic respiration was less sensitive to P addition, despite its increasing microbial biomass. However, simultaneous N and P addition did ameliorate negative N effects. These results show that previously observed variation in the response of heterotrophic respiration to N addition can be explained by soil C availability and pH status, widely measured factors which can be used to predict how grassland C fluxes may change under continuing nutrient deposition.

Original language	English
Article number	110000
Journal	Soil Biology and Biochemistry
Volume	212
DOIs	https://doi.org/10.1016/j.soilbio.2025.110000
State	Published - Jan 2026

Funding

We acknowledge Hanah Farah and Esther Young for their help with laboratory analyses. We also thank Allison Gill, Charlotte Riggs, and Carol Adair for assistance with curve fitting. This work was supported through a National Science Foundation (NSF) award to SEH (NSF DEB-1556529). We thank PIs from the Nutrient Network ( http://nutnet.org ) for their continuous efforts on collecting field data. Coordination and data management of Nutrient Network project have been supported by the National Science Foundation Research Coordination Network (NSF-DEB-1042132 to ETB and EWS) and Cedar Creek Long-Term Ecological Research (NSF-DEB-1234162 and and DEB-1831944 to EWS, ETB, SEH and others), and the UMN Institute on the Environment (DG-0001-13). Oak Ridge National Laboratory is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy. PNNL is a multi-program national laboratory operated by Battelle for the DOE under Contract DE-AC05-76RLO 1830. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract no. DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doe-publicaccess-plan).We acknowledge Hanah Farah and Esther Young for their help with laboratory analyses. We also thank Allison Gill, Charlotte Riggs, and Carol Adair for assistance with curve fitting. This work was supported through a National Science Foundation (NSF) award to SEH (NSF DEB-1556529). We thank PIs from the Nutrient Network (http://nutnet.org) for their continuous efforts on collecting field data. Coordination and data management of Nutrient Network project have been supported by the National Science Foundation Research Coordination Network (NSF-DEB-1042132 to ETB and EWS) and Cedar Creek Long-Term Ecological Research (NSF-DEB-1234162 and and DEB-1831944 to EWS, ETB, SEH and others), and the UMN Institute on the Environment (DG-0001-13). Oak Ridge National Laboratory is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy. PNNL is a multi-program national laboratory operated by Battelle for the DOE under Contract DE-AC05-76RLO 1830. Notice: This manuscript has been authored by UT-Battelle, LLC, under contract no. DE-AC05-00OR22725 with the US Department of Energy (DOE). The US government retains and the publisher, by accepting the article for publication, acknowledges that the US government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for US government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-publicaccess-plan ).

Keywords

Enzymes
Heterotrophic respiration
Microbial biomass
N addition
Nutrient network
P addition
Soil organic matter decomposition

Access to Document

10.1016/j.soilbio.2025.110000

Cite this

DeLancey, L. C., Zhao, Q., Keller, A. B., Walter, C. A., Hofmockel, K. S., Mayes, M. A., Seabloom, E. W., Borer, E. T., Leakey, A. D. B., & Hobbie, S. E. (2026). Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition. Soil Biology and Biochemistry, 212, Article 110000. https://doi.org/10.1016/j.soilbio.2025.110000

@article{e52c6d68b76342b3be6208ad1c95e68f,

title = "Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition",

abstract = "Previous work has found that anthropogenic inputs of nitrogen (N) and phosphorus (P) impact heterotrophic respiration during soil organic matter decomposition in grasslands, a critical pathway through which carbon (C) is lost from soil to the atmosphere. While N addition typically reduces heterotrophic respiration, why the strength and direction of this N effect varies among sites is unclear. To address this, we conducted a 339-day laboratory incubation to measure heterotrophic respiration from nine grasslands across North America that have received 10 years of factorial N and P fertilization. N addition reduced cumulative respiration most at sites with low pH, low microbial allocation towards N acquisition, and high soil C concentration and availability. However, N addition had neutral rather than positive effects on heterotrophic respiration in sites with high pH and decomposer allocation towards N acquisition. Across sites, a decade of N addition reduced heterotrophic respiration by ∼24 \%, driven by reductions in microbial biomass. Heterotrophic respiration was less sensitive to P addition, despite its increasing microbial biomass. However, simultaneous N and P addition did ameliorate negative N effects. These results show that previously observed variation in the response of heterotrophic respiration to N addition can be explained by soil C availability and pH status, widely measured factors which can be used to predict how grassland C fluxes may change under continuing nutrient deposition.",

keywords = "Enzymes, Heterotrophic respiration, Microbial biomass, N addition, Nutrient network, P addition, Soil organic matter decomposition",

author = "DeLancey, \{Lang C.\} and Qian Zhao and Keller, \{Adrienne B.\} and Walter, \{Christopher A.\} and Hofmockel, \{Kirsten S.\} and Mayes, \{Melanie A.\} and Seabloom, \{Eric W.\} and Borer, \{Elizabeth T.\} and Leakey, \{Andrew D.B.\} and Hobbie, \{Sarah E.\}",

note = "Publisher Copyright: {\textcopyright} 2025 Elsevier Ltd",

year = "2026",

month = jan,

doi = "10.1016/j.soilbio.2025.110000",

language = "English",

volume = "212",

journal = "Soil Biology and Biochemistry",

issn = "0038-0717",

publisher = "Elsevier",

}

DeLancey, LC, Zhao, Q, Keller, AB, Walter, CA, Hofmockel, KS, Mayes, MA, Seabloom, EW, Borer, ET, Leakey, ADB & Hobbie, SE 2026, 'Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition', Soil Biology and Biochemistry, vol. 212, 110000. https://doi.org/10.1016/j.soilbio.2025.110000

TY - JOUR

T1 - Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition

AU - DeLancey, Lang C.

AU - Zhao, Qian

AU - Keller, Adrienne B.

AU - Walter, Christopher A.

AU - Hofmockel, Kirsten S.

AU - Mayes, Melanie A.

AU - Seabloom, Eric W.

AU - Borer, Elizabeth T.

AU - Leakey, Andrew D.B.

AU - Hobbie, Sarah E.

PY - 2026/1

Y1 - 2026/1

N2 - Previous work has found that anthropogenic inputs of nitrogen (N) and phosphorus (P) impact heterotrophic respiration during soil organic matter decomposition in grasslands, a critical pathway through which carbon (C) is lost from soil to the atmosphere. While N addition typically reduces heterotrophic respiration, why the strength and direction of this N effect varies among sites is unclear. To address this, we conducted a 339-day laboratory incubation to measure heterotrophic respiration from nine grasslands across North America that have received 10 years of factorial N and P fertilization. N addition reduced cumulative respiration most at sites with low pH, low microbial allocation towards N acquisition, and high soil C concentration and availability. However, N addition had neutral rather than positive effects on heterotrophic respiration in sites with high pH and decomposer allocation towards N acquisition. Across sites, a decade of N addition reduced heterotrophic respiration by ∼24 %, driven by reductions in microbial biomass. Heterotrophic respiration was less sensitive to P addition, despite its increasing microbial biomass. However, simultaneous N and P addition did ameliorate negative N effects. These results show that previously observed variation in the response of heterotrophic respiration to N addition can be explained by soil C availability and pH status, widely measured factors which can be used to predict how grassland C fluxes may change under continuing nutrient deposition.

AB - Previous work has found that anthropogenic inputs of nitrogen (N) and phosphorus (P) impact heterotrophic respiration during soil organic matter decomposition in grasslands, a critical pathway through which carbon (C) is lost from soil to the atmosphere. While N addition typically reduces heterotrophic respiration, why the strength and direction of this N effect varies among sites is unclear. To address this, we conducted a 339-day laboratory incubation to measure heterotrophic respiration from nine grasslands across North America that have received 10 years of factorial N and P fertilization. N addition reduced cumulative respiration most at sites with low pH, low microbial allocation towards N acquisition, and high soil C concentration and availability. However, N addition had neutral rather than positive effects on heterotrophic respiration in sites with high pH and decomposer allocation towards N acquisition. Across sites, a decade of N addition reduced heterotrophic respiration by ∼24 %, driven by reductions in microbial biomass. Heterotrophic respiration was less sensitive to P addition, despite its increasing microbial biomass. However, simultaneous N and P addition did ameliorate negative N effects. These results show that previously observed variation in the response of heterotrophic respiration to N addition can be explained by soil C availability and pH status, widely measured factors which can be used to predict how grassland C fluxes may change under continuing nutrient deposition.

KW - Enzymes

KW - Heterotrophic respiration

KW - Microbial biomass

KW - N addition

KW - Nutrient network

KW - P addition

KW - Soil organic matter decomposition

UR - https://www.scopus.com/pages/publications/105017850914

U2 - 10.1016/j.soilbio.2025.110000

DO - 10.1016/j.soilbio.2025.110000

M3 - Article

AN - SCOPUS:105017850914

SN - 0038-0717

VL - 212

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

M1 - 110000

ER -

Carbon availability, soil pH, and microbial allocation to nitrogen acquisition shape grassland heterotrophic respiration in response to a decade of nitrogen addition

Abstract

Funding

Keywords

Access to Document

Other files and links

Fingerprint

Cite this