Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh

Ylva S. Olsen, Armel Dausse, Angus Garbutt, Hilary Ford, David N. Thomas, David L. Jones

Research output: Contribution to journalArticle

46 Citations (Scopus)

Abstract

We examined the impact of long-term cattle grazing on soil processes and microbial activity in a temperate salt marsh. Soil conditions, microbial biomass and respiration, mineralization and denitrification rates were measured in upper salt marsh that had been ungrazed or cattle grazed for several decades. Increased microbial biomass and soil respiration were observed in grazed marsh, most likely stimulated by enhanced rates of root turnover and root exudation. We found a significant positive effect of grazing on potential N mineralization rates measured in the laboratory, but this difference did not translate to in situ net mineralization measured monthly from May to September. Rates of denitrification were lowest in the grazed marsh and appeared to be limited by nitrate availability, possibly due to more anoxic conditions and lower rates of nitrification. The major effect of grazing on N cycling therefore appeared to be in limiting losses of N through denitrification, which may lead to enhanced nutrient availability to saltmarsh plants, but a reduced ability of the marsh to act as a buffer for land-derived nutrients to adjacent coastal areas. Additionally, we investigated if grazing influences the rates of turnover of labile and refractory C in saltmarsh soils by adding 14C-labelled leaf litter or root exudates to soil samples and monitoring the evolution of 14CO2. Grazing had little effect on the rates of mineralization of 14C used as a respiratory substrate, but a larger proportion of 14C was partitioned into microbial biomass and immobilized in long- and medium-term storage pools in the grazed treatment. Grazing slowed down the turnover of the microbial biomass, which resulted in longer turnover times for both leaf litter and root exudates. Grazing may therefore affect the longevity of C in the soil and alter C storage and utilization pathways in the microbial community.

Original languageEnglish
Pages (from-to)531-541
Number of pages11
JournalSoil Biology and Biochemistry
Volume43
Issue number3
DOIs
Publication statusPublished - Mar 2011

Fingerprint

Wetlands
salt marshes
saltmarsh
cattle
Nitrogen
Soil
Carbon
Salts
grazing
Denitrification
Biomass
carbon
nitrogen
microbial biomass
mineralization
turnover
denitrification
marshes
marsh
Exudates and Transudates

Cite this

Olsen, Ylva S. ; Dausse, Armel ; Garbutt, Angus ; Ford, Hilary ; Thomas, David N. ; Jones, David L. / Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh. In: Soil Biology and Biochemistry. 2011 ; Vol. 43, No. 3. pp. 531-541.
@article{e42c156802e8472ea5e414e726b7af50,
title = "Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh",
abstract = "We examined the impact of long-term cattle grazing on soil processes and microbial activity in a temperate salt marsh. Soil conditions, microbial biomass and respiration, mineralization and denitrification rates were measured in upper salt marsh that had been ungrazed or cattle grazed for several decades. Increased microbial biomass and soil respiration were observed in grazed marsh, most likely stimulated by enhanced rates of root turnover and root exudation. We found a significant positive effect of grazing on potential N mineralization rates measured in the laboratory, but this difference did not translate to in situ net mineralization measured monthly from May to September. Rates of denitrification were lowest in the grazed marsh and appeared to be limited by nitrate availability, possibly due to more anoxic conditions and lower rates of nitrification. The major effect of grazing on N cycling therefore appeared to be in limiting losses of N through denitrification, which may lead to enhanced nutrient availability to saltmarsh plants, but a reduced ability of the marsh to act as a buffer for land-derived nutrients to adjacent coastal areas. Additionally, we investigated if grazing influences the rates of turnover of labile and refractory C in saltmarsh soils by adding 14C-labelled leaf litter or root exudates to soil samples and monitoring the evolution of 14CO2. Grazing had little effect on the rates of mineralization of 14C used as a respiratory substrate, but a larger proportion of 14C was partitioned into microbial biomass and immobilized in long- and medium-term storage pools in the grazed treatment. Grazing slowed down the turnover of the microbial biomass, which resulted in longer turnover times for both leaf litter and root exudates. Grazing may therefore affect the longevity of C in the soil and alter C storage and utilization pathways in the microbial community.",
keywords = "Carbon cycling, Herbivory, Nitrogen cycle, Nitrogen mineralization, Salinity, Saltmarsh vegetation, Soil compaction",
author = "Olsen, {Ylva S.} and Armel Dausse and Angus Garbutt and Hilary Ford and Thomas, {David N.} and Jones, {David L.}",
year = "2011",
month = "3",
doi = "10.1016/j.soilbio.2010.11.018",
language = "English",
volume = "43",
pages = "531--541",
journal = "Soil Biology & Biochemistry",
issn = "0038-0717",
publisher = "Pergamon",
number = "3",

}

Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh. / Olsen, Ylva S.; Dausse, Armel; Garbutt, Angus; Ford, Hilary; Thomas, David N.; Jones, David L.

In: Soil Biology and Biochemistry, Vol. 43, No. 3, 03.2011, p. 531-541.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Cattle grazing drives nitrogen and carbon cycling in a temperate salt marsh

AU - Olsen, Ylva S.

AU - Dausse, Armel

AU - Garbutt, Angus

AU - Ford, Hilary

AU - Thomas, David N.

AU - Jones, David L.

PY - 2011/3

Y1 - 2011/3

N2 - We examined the impact of long-term cattle grazing on soil processes and microbial activity in a temperate salt marsh. Soil conditions, microbial biomass and respiration, mineralization and denitrification rates were measured in upper salt marsh that had been ungrazed or cattle grazed for several decades. Increased microbial biomass and soil respiration were observed in grazed marsh, most likely stimulated by enhanced rates of root turnover and root exudation. We found a significant positive effect of grazing on potential N mineralization rates measured in the laboratory, but this difference did not translate to in situ net mineralization measured monthly from May to September. Rates of denitrification were lowest in the grazed marsh and appeared to be limited by nitrate availability, possibly due to more anoxic conditions and lower rates of nitrification. The major effect of grazing on N cycling therefore appeared to be in limiting losses of N through denitrification, which may lead to enhanced nutrient availability to saltmarsh plants, but a reduced ability of the marsh to act as a buffer for land-derived nutrients to adjacent coastal areas. Additionally, we investigated if grazing influences the rates of turnover of labile and refractory C in saltmarsh soils by adding 14C-labelled leaf litter or root exudates to soil samples and monitoring the evolution of 14CO2. Grazing had little effect on the rates of mineralization of 14C used as a respiratory substrate, but a larger proportion of 14C was partitioned into microbial biomass and immobilized in long- and medium-term storage pools in the grazed treatment. Grazing slowed down the turnover of the microbial biomass, which resulted in longer turnover times for both leaf litter and root exudates. Grazing may therefore affect the longevity of C in the soil and alter C storage and utilization pathways in the microbial community.

AB - We examined the impact of long-term cattle grazing on soil processes and microbial activity in a temperate salt marsh. Soil conditions, microbial biomass and respiration, mineralization and denitrification rates were measured in upper salt marsh that had been ungrazed or cattle grazed for several decades. Increased microbial biomass and soil respiration were observed in grazed marsh, most likely stimulated by enhanced rates of root turnover and root exudation. We found a significant positive effect of grazing on potential N mineralization rates measured in the laboratory, but this difference did not translate to in situ net mineralization measured monthly from May to September. Rates of denitrification were lowest in the grazed marsh and appeared to be limited by nitrate availability, possibly due to more anoxic conditions and lower rates of nitrification. The major effect of grazing on N cycling therefore appeared to be in limiting losses of N through denitrification, which may lead to enhanced nutrient availability to saltmarsh plants, but a reduced ability of the marsh to act as a buffer for land-derived nutrients to adjacent coastal areas. Additionally, we investigated if grazing influences the rates of turnover of labile and refractory C in saltmarsh soils by adding 14C-labelled leaf litter or root exudates to soil samples and monitoring the evolution of 14CO2. Grazing had little effect on the rates of mineralization of 14C used as a respiratory substrate, but a larger proportion of 14C was partitioned into microbial biomass and immobilized in long- and medium-term storage pools in the grazed treatment. Grazing slowed down the turnover of the microbial biomass, which resulted in longer turnover times for both leaf litter and root exudates. Grazing may therefore affect the longevity of C in the soil and alter C storage and utilization pathways in the microbial community.

KW - Carbon cycling

KW - Herbivory

KW - Nitrogen cycle

KW - Nitrogen mineralization

KW - Salinity

KW - Saltmarsh vegetation

KW - Soil compaction

UR - http://www.scopus.com/inward/record.url?scp=78751584830&partnerID=8YFLogxK

U2 - 10.1016/j.soilbio.2010.11.018

DO - 10.1016/j.soilbio.2010.11.018

M3 - Article

VL - 43

SP - 531

EP - 541

JO - Soil Biology & Biochemistry

JF - Soil Biology & Biochemistry

SN - 0038-0717

IS - 3

ER -