Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link

Valeria L. Cenini; Dario A. Fornara; Geoffrey McMullan; Nigel Ternan; Kate Lajtha; Michael J. Crawley

doi:10.1007/s10533-015-0157-5

Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link

Valeria L. Cenini, Dario A. Fornara^*, Geoffrey McMullan, Nigel Ternan, Kate Lajtha, Michael J. Crawley

^*Corresponding author for this work

Research output: Contribution to journal › Article

30 Citations (Scopus)

253 Downloads (Pure)

Abstract

Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme β-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19 years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO₃), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential ‘enzyme link’ between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the ‘enzyme link’ occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG ‘enzyme link’ will have far reaching implications for long-term C sequestration in grassland soils.

Original language	English
Pages (from-to)	301-313
Number of pages	13
Journal	Biogeochemistry
Volume	126
Issue number	3
Early online date	14 Nov 2015
DOIs	https://doi.org/10.1007/s10533-015-0157-5
Publication status	Published - 01 Dec 2015
Externally published	Yes

Keywords

Extracellular enzyme activity
Fertilization
Liming
Root C:N ratio
Soil carbon sequestration
β-1,4-Glucosidase

ASJC Scopus subject areas

Environmental Chemistry
Water Science and Technology
Earth-Surface Processes

Access to Document

10.1007/s10533-015-0157-5Licence: CC BY

Chronic nitrogen fertilization and carbon sequestration in grassland soils
The Author(s) 2015. This article is published with open access at Springerlink.com This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http:// creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made.
Final published version, 937 KBLicence: CC BY

Link to publication in Scopus

Fingerprint Dive into the research topics of 'Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link'. Together they form a unique fingerprint.

Cite this

@article{748fe32aeb6940019c0f14530b109859,

title = "Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link",

abstract = "Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme β-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19 years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO3), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential {\textquoteleft}enzyme link{\textquoteright} between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the {\textquoteleft}enzyme link{\textquoteright} occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG {\textquoteleft}enzyme link{\textquoteright} will have far reaching implications for long-term C sequestration in grassland soils.",

keywords = "Extracellular enzyme activity, Fertilization, Liming, Root C:N ratio, Soil carbon sequestration, β-1,4-Glucosidase",

author = "Cenini, {Valeria L.} and Fornara, {Dario A.} and Geoffrey McMullan and Nigel Ternan and Kate Lajtha and Crawley, {Michael J.}",

year = "2015",

month = dec,

day = "1",

doi = "10.1007/s10533-015-0157-5",

language = "English",

volume = "126",

pages = "301--313",

journal = "Biogeochemistry",

issn = "0168-2563",

publisher = "Springer Netherlands",

number = "3",

}

TY - JOUR

T1 - Chronic nitrogen fertilization and carbon sequestration in grassland soils: evidence of a microbial enzyme link

AU - Cenini, Valeria L.

AU - Fornara, Dario A.

AU - McMullan, Geoffrey

AU - Ternan, Nigel

AU - Lajtha, Kate

AU - Crawley, Michael J.

PY - 2015/12/1

Y1 - 2015/12/1

N2 - Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme β-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19 years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO3), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential ‘enzyme link’ between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the ‘enzyme link’ occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG ‘enzyme link’ will have far reaching implications for long-term C sequestration in grassland soils.

AB - Chronic nitrogen (N) fertilization can greatly affect soil carbon (C) sequestration by altering biochemical interactions between plant detritus and soil microbes. In lignin-rich forest soils, chronic N additions tend to increase soil C content partly by decreasing the activity of lignin-degrading enzymes. In cellulose-rich grassland soils it is not clear whether cellulose-degrading enzymes are also inhibited by N additions and what consequences this might have on changes in soil C content. Here we address whether chronic N fertilization has affected (1) the C content of light versus heavier soil fractions, and (2) the activity of four extracellular enzymes including the C-acquiring enzyme β-1,4-glucosidase (BG; necessary for cellulose hydrolysis). We found that 19 years of chronic N-only addition to permanent grassland have significantly increased soil C sequestration in heavy but not in light soil density fractions, and this C accrual was associated with a significant increase (and not decrease) of BG activity. Chronic N fertilization may increase BG activity because greater N availability reduces root C:N ratios thus increasing microbial demand for C, which is met by C inputs from enhanced root C pools in N-only fertilized soils. However, BG activity and total root mass strongly decreased in high pH soils under the application of lime (i.e. CaCO3), which reduced the ability of these organo-mineral soils to gain more C per units of N added. Our study is the first to show a potential ‘enzyme link’ between (1) long-term additions of inorganic N to grassland soils, and (2) the greater C content of organo-mineral soil fractions. Our new hypothesis is that the ‘enzyme link’ occurs because (a) BG activity is stimulated by increased microbial C demand relative to N under chronic fertilization, and (b) increased BG activity causes more C from roots and from microbial metabolites to accumulate and stabilize into organo-mineral C fractions. We suggest that any combination of management practices that can influence the BG ‘enzyme link’ will have far reaching implications for long-term C sequestration in grassland soils.

KW - Extracellular enzyme activity

KW - Fertilization

KW - Liming

KW - Root C:N ratio

KW - Soil carbon sequestration

KW - β-1,4-Glucosidase

UR - http://www.scopus.com/inward/record.url?scp=84951569077&partnerID=8YFLogxK

U2 - 10.1007/s10533-015-0157-5

DO - 10.1007/s10533-015-0157-5

M3 - Article

AN - SCOPUS:84951569077

VL - 126

SP - 301

EP - 313

JO - Biogeochemistry

JF - Biogeochemistry

SN - 0168-2563

IS - 3

ER -