Abstract
Abstract We investigated the effects of spring barley growth on nitrogen (N) transformations and rhizosphere microbial processes in a controlled system under elevated carbon dioxide (CO 2 ) at two levels of N fertilization (applied with 15 N labelling). After 25 d, elevated CO 2 (twice ambient) increased plant growth (dry weight, DW) by 141% at low‐N fertilization and by 60% at high‐N fertilization, but its positive effect on the root‐to‐shoot ratio was only significant at low‐N input. As a result of this plant response, elevated CO 2 caused a greater soil CO 2 efflux, rhizosphere soil DW, and soil microbial biomass under N‐limiting conditions than under high N availability. Elevated CO 2 also caused a significant ( P < 0.001) increase in the N recovered by the plant from both the labelled (N f ) and unlabelled (N s + N uf ) N pools. The dynamics of N in the system as affected by elevated CO 2 were driven principally by mineralization–immobilization turnover, with little loss by denitrification. Under N‐limiting conditions, there is evidence to suggest enhanced nutrient release from soil organic matter (SOM) pools—a process which could be defined as priming. The results of our experiment did not indicate a direct plant‐mediated effect of elevated CO 2 on nitrous oxide (N 2 O) fluxes or denitrification activity.
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Claims 12
Claim · model-written summary
At low nitrogen, elevated carbon dioxide increased barley dry weight by 141%.
- Taxon
- spring barley
.jpg?width=60)
Hordeum vulgaret0 - Treatment
- elevated CO 2 (twice ambient)e0
- Outcome
- plant growth (dry weight, DW)e0
- Direction
- increasede0
- Value
- 141%e0
- Qualifier
- low‐N fertilizatione0
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
.jpg?width=500)
Verbatim
e0“elevated CO 2 (twice ambient) increased plant growth (dry weight, DW) by 141% at low‐N fertilization”
t0“spring barley growth”
Claim · model-written summary
At high nitrogen, elevated carbon dioxide increased barley dry weight by 60%.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- elevated CO 2 (twice ambient)e0
- Outcome
- plant growth (dry weight, DW)e0
- Direction
- increasede0
- Value
- 60%e0
- Qualifier
- high‐N fertilizatione0
- Comparator
- ambiente0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO 2 (twice ambient) increased plant growth (dry weight, DW) by 141% at low‐N fertilization and by 60% at high‐N fertilization”
t0“spring barley growth”
Claim · model-written summary
Elevated carbon dioxide significantly increased the root-to-shoot ratio only at low nitrogen.
- Taxon
- spring barleyHordeum vulgaret0
- Outcome
- root‐to‐shoot ratioe0
- Direction
- positivee0
- Qualifier
- low‐N inpute0
Not reportedTreatmentComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“its positive effect on the root‐to‐shoot ratio was only significant at low‐N input.”
t0“spring barley growth”
Claim · model-written summary
Under nitrogen limitation, elevated carbon dioxide caused greater soil carbon dioxide efflux.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- elevated CO 2e0
- Outcome
- soil CO 2 effluxe0
- Direction
- greatere0
- Comparator
- high N availabilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO 2 caused a greater soil CO 2 efflux, rhizosphere soil DW, and soil microbial biomass under N‐limiting conditions than under high N availability.”
t0“spring barley growth”
Claim · model-written summary
Under nitrogen limitation, elevated carbon dioxide caused greater rhizosphere soil dry weight.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- elevated CO 2e0
- Outcome
- rhizosphere soil DWe0
- Direction
- greatere0
- Comparator
- high N availabilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO 2 caused a greater soil CO 2 efflux, rhizosphere soil DW, and soil microbial biomass under N‐limiting conditions than under high N availability.”
t0“spring barley growth”
Claim · model-written summary
Under nitrogen limitation, elevated carbon dioxide caused greater soil microbial biomass.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- elevated CO 2e0
- Outcome
- soil microbial biomasse0
- Direction
- greatere0
- Comparator
- high N availabilitye0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“elevated CO 2 caused a greater soil CO 2 efflux, rhizosphere soil DW, and soil microbial biomass under N‐limiting conditions than under high N availability.”
t0“spring barley growth”
Claim · model-written summary
Elevated carbon dioxide significantly increased plant recovery of labeled nitrogen.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- Elevated CO 2e0
- Outcome
- N recovered by the plant from both the labelled (N f )e0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO 2 also caused a significant ( P < 0.001) increase in the N recovered by the plant from both the labelled (N f ) and unlabelled (N s + N uf ) N pools.”
t0“spring barley growth”
Claim · model-written summary
Elevated carbon dioxide significantly increased plant recovery of unlabeled nitrogen.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- Elevated CO 2e0
- Outcome
- unlabelled (N s + N uf ) N poolse0
- Direction
- increasee0
Not reportedComparator
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Elevated CO 2 also caused a significant ( P < 0.001) increase in the N recovered by the plant from both the labelled (N f ) and unlabelled (N s + N uf ) N pools.”
t0“spring barley growth”
Claim · model-written summary
Mineralization–immobilization turnover principally drove soil nitrogen dynamics.
- Taxon
- spring barleyHordeum vulgaret0
- Outcome
- dynamics of Ne0
- Qualifier
- mineralization–immobilization turnovere0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“The dynamics of N in the system as affected by elevated CO 2 were driven principally by mineralization–immobilization turnover, with little loss by denitrification.”
t0“spring barley growth”
Claim · model-written summary
Nitrogen loss by denitrification was small.
- Taxon
- spring barleyHordeum vulgaret0
- Outcome
- little loss by denitrificatione0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“with little loss by denitrification.”
t0“spring barley growth”
Claim · model-written summary
Evidence suggested enhanced nutrient release from soil organic matter under nitrogen limitation.
- Taxon
- spring barleyHordeum vulgaret0
- Outcome
- nutrient release from soil organic matter (SOM) poolse0
- Direction
- enhancede0
- Qualifier
- N‐limiting conditionse0
Not reportedSetting
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“Under N‐limiting conditions, there is evidence to suggest enhanced nutrient release from soil organic matter (SOM) pools”
t0“spring barley growth”
Claim · model-written summary
The experiment did not indicate a direct plant-mediated effect on nitrous oxide fluxes or denitrification.
- Taxon
- spring barleyHordeum vulgaret0
- Treatment
- elevated CO 2e0
- Outcome
- nitrous oxide (N 2 O) fluxes or denitrification activitye0
Not reportedComparatorDirection
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“did not indicate a direct plant‐mediated effect of elevated CO 2 on nitrous oxide (N 2 O) fluxes or denitrification activity.”
t0“spring barley growth”
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See all 22 papers →Claims are grouped by organism, treatment and what was measured or targeted. A paper counts as positive when any of its claims in the group is positive.