Relationships between C and N availability, substrate age, and natural abundance 13C and 15N signatures of soil microbial biomass in a semiarid climate

Jeff S. Coyle; Paul Dijkstra; Richard R. Doucett; Egbert Schwartz; Stephen C. Hart; Bruce A. Hungate

doi:10.1016/j.soilbio.2009.04.022

Relationships between C and N availability, substrate age, and natural abundance ¹³C and ¹⁵N signatures of soil microbial biomass in a semiarid climate

Jeff S. Coyle, Paul Dijkstra, Richard R. Doucett, Egbert Schwartz, Stephen C. Hart, Bruce A. Hungate

Biological Sciences

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

44 Scopus citations

Abstract

Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial biomass across a three million year old semiarid substrate age gradient in northern Arizona. The δ¹⁵N of soil microbial biomass was on average 7.2‰ higher than that of soil total N for all substrate ages and 1.6‰ higher than that of extractable N, but not significantly different for the youngest and oldest sites. Microbial ¹⁵N enrichment relative to soil extractable and total N was low at the youngest site, increased to a maximum after 55,000 years, and then decreased slightly with age. The degree of ¹⁵N enrichment of microbial biomass correlated negatively with the C:N mass ratio of the soil extractable pool. The δ¹³C signature of soil microbial biomass was 1.4‰ and 4.6‰ enriched relative to that of soil total and extractable pools respectively and showed significant differences between sites. However, microbial ¹³C enrichment was unrelated to measures of C and N availability. Our results confirm that ¹⁵N, but not ¹³C enrichment of soil microbial biomass reflects changes in C and N availability and N processing during long-term ecosystem development.

Original language	English (US)
Pages (from-to)	1605-1611
Number of pages	7
Journal	Soil Biology and Biochemistry
Volume	41
Issue number	8
DOIs	https://doi.org/10.1016/j.soilbio.2009.04.022
State	Published - Aug 2009

Keywords

Microbial biomass
Natural isotopic abundance
Nitrogen and carbon availability
Nitrogen mineralization
Piñon-juniper
Semiarid
Stable isotopes
Substrate age gradient

ASJC Scopus subject areas

Microbiology
Soil Science

Access to Document

10.1016/j.soilbio.2009.04.022

Cite this

@article{7e913da4c8ce4cabb0b7be9ebd880808,

title = "Relationships between C and N availability, substrate age, and natural abundance 13C and 15N signatures of soil microbial biomass in a semiarid climate",

abstract = "Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial biomass across a three million year old semiarid substrate age gradient in northern Arizona. The δ15N of soil microbial biomass was on average 7.2‰ higher than that of soil total N for all substrate ages and 1.6‰ higher than that of extractable N, but not significantly different for the youngest and oldest sites. Microbial 15N enrichment relative to soil extractable and total N was low at the youngest site, increased to a maximum after 55,000 years, and then decreased slightly with age. The degree of 15N enrichment of microbial biomass correlated negatively with the C:N mass ratio of the soil extractable pool. The δ13C signature of soil microbial biomass was 1.4‰ and 4.6‰ enriched relative to that of soil total and extractable pools respectively and showed significant differences between sites. However, microbial 13C enrichment was unrelated to measures of C and N availability. Our results confirm that 15N, but not 13C enrichment of soil microbial biomass reflects changes in C and N availability and N processing during long-term ecosystem development.",

keywords = "Microbial biomass, Natural isotopic abundance, Nitrogen and carbon availability, Nitrogen mineralization, Pi{\~n}on-juniper, Semiarid, Stable isotopes, Substrate age gradient",

author = "Coyle, {Jeff S.} and Paul Dijkstra and Doucett, {Richard R.} and Egbert Schwartz and Hart, {Stephen C.} and Hungate, {Bruce A.}",

note = "Funding Information: We appreciate help from Jaina Moan, Ben Moan, and Paul Selmants. This project is financially supported by grants from the National Science Foundation (DEB 0416223), the US Department of Agriculture National Research Initiative (NRI 2005-35107-16191), the Northern Arizona University Technology and Research Initiative Fund (Environmental Research, Development, and Education for the New Economy) and by McIntire-Stennis appropriations to NAU and the State of Arizona. We also acknowledge insightful comments from the anonymous reviewers.",

year = "2009",

month = aug,

doi = "10.1016/j.soilbio.2009.04.022",

language = "English (US)",

volume = "41",

pages = "1605--1611",

journal = "Soil Biology and Biochemistry",

issn = "0038-0717",

publisher = "Elsevier Limited",

number = "8",

}

TY - JOUR

T1 - Relationships between C and N availability, substrate age, and natural abundance 13C and 15N signatures of soil microbial biomass in a semiarid climate

AU - Coyle, Jeff S.

AU - Dijkstra, Paul

AU - Doucett, Richard R.

AU - Schwartz, Egbert

AU - Hart, Stephen C.

AU - Hungate, Bruce A.

N1 - Funding Information: We appreciate help from Jaina Moan, Ben Moan, and Paul Selmants. This project is financially supported by grants from the National Science Foundation (DEB 0416223), the US Department of Agriculture National Research Initiative (NRI 2005-35107-16191), the Northern Arizona University Technology and Research Initiative Fund (Environmental Research, Development, and Education for the New Economy) and by McIntire-Stennis appropriations to NAU and the State of Arizona. We also acknowledge insightful comments from the anonymous reviewers.

PY - 2009/8

Y1 - 2009/8

N2 - Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial biomass across a three million year old semiarid substrate age gradient in northern Arizona. The δ15N of soil microbial biomass was on average 7.2‰ higher than that of soil total N for all substrate ages and 1.6‰ higher than that of extractable N, but not significantly different for the youngest and oldest sites. Microbial 15N enrichment relative to soil extractable and total N was low at the youngest site, increased to a maximum after 55,000 years, and then decreased slightly with age. The degree of 15N enrichment of microbial biomass correlated negatively with the C:N mass ratio of the soil extractable pool. The δ13C signature of soil microbial biomass was 1.4‰ and 4.6‰ enriched relative to that of soil total and extractable pools respectively and showed significant differences between sites. However, microbial 13C enrichment was unrelated to measures of C and N availability. Our results confirm that 15N, but not 13C enrichment of soil microbial biomass reflects changes in C and N availability and N processing during long-term ecosystem development.

AB - Soil microbial organisms are central to carbon (C) and nitrogen (N) transformations in soils, yet not much is known about the stable isotope composition of these essential regulators of element cycles. We investigated the relationship between C and N availability and stable C and N isotope composition of soil microbial biomass across a three million year old semiarid substrate age gradient in northern Arizona. The δ15N of soil microbial biomass was on average 7.2‰ higher than that of soil total N for all substrate ages and 1.6‰ higher than that of extractable N, but not significantly different for the youngest and oldest sites. Microbial 15N enrichment relative to soil extractable and total N was low at the youngest site, increased to a maximum after 55,000 years, and then decreased slightly with age. The degree of 15N enrichment of microbial biomass correlated negatively with the C:N mass ratio of the soil extractable pool. The δ13C signature of soil microbial biomass was 1.4‰ and 4.6‰ enriched relative to that of soil total and extractable pools respectively and showed significant differences between sites. However, microbial 13C enrichment was unrelated to measures of C and N availability. Our results confirm that 15N, but not 13C enrichment of soil microbial biomass reflects changes in C and N availability and N processing during long-term ecosystem development.

KW - Microbial biomass

KW - Natural isotopic abundance

KW - Nitrogen and carbon availability

KW - Nitrogen mineralization

KW - Piñon-juniper

KW - Semiarid

KW - Stable isotopes

KW - Substrate age gradient

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U2 - 10.1016/j.soilbio.2009.04.022

DO - 10.1016/j.soilbio.2009.04.022

M3 - Article

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SN - 0038-0717

VL - 41

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EP - 1611

JO - Soil Biology and Biochemistry

JF - Soil Biology and Biochemistry

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