Short-term carbon input increases microbial nitrogen demand, but not microbial nitrogen mining, in a set of boreal forest soils
(2017) In Biogeochemistry 136(3). p.261-278- Abstract
Rising carbon dioxide (CO2) concentrations and temperatures are expected to stimulate plant productivity and ecosystem C sequestration, but these effects require a concurrent increase in N availability for plants. Plants might indirectly promote N availability as they release organic C into the soil (e.g., by root exudation) that can increase microbial soil organic matter (SOM) decomposition (“priming effect”), and possibly the enzymatic breakdown of N-rich polymers, such as proteins, into bio-available units (“N mining”). We tested the adjustment of protein depolymerization to changing soil C and N availability in a laboratory experiment. We added easily available C or N sources to six boreal forest soils, and determined... (More)
Rising carbon dioxide (CO2) concentrations and temperatures are expected to stimulate plant productivity and ecosystem C sequestration, but these effects require a concurrent increase in N availability for plants. Plants might indirectly promote N availability as they release organic C into the soil (e.g., by root exudation) that can increase microbial soil organic matter (SOM) decomposition (“priming effect”), and possibly the enzymatic breakdown of N-rich polymers, such as proteins, into bio-available units (“N mining”). We tested the adjustment of protein depolymerization to changing soil C and N availability in a laboratory experiment. We added easily available C or N sources to six boreal forest soils, and determined soil organic C mineralization, gross protein depolymerization and gross ammonification rates (using 15N pool dilution assays), and potential extracellular enzyme activities after 1 week of incubation. Added C sources were 13C-labelled to distinguish substrate from soil derived C mineralization. Observed effects reflect short-term adaptations of non-symbiotic soil microorganisms to increased C or N availability. Although C input promoted microbial growth and N demand, we did not find indicators of increased N mobilization from SOM polymers, given that none of the soils showed a significant increase in protein depolymerization, and only one soil showed a significant increase in N-targeting enzymes. Instead, our findings suggest that microorganisms immobilized the already available N more efficiently, as indicated by decreased ammonification and inorganic N concentrations. Likewise, although N input stimulated ammonification, we found no significant effect on protein depolymerization. Although our findings do not rule out in general that higher plant-soil C allocation can promote microbial N mining, they suggest that such an effect can be counteracted, at least in the short term, by increased microbial N immobilization, further aggravating plant N limitation.
(Less)
- author
- Wild, Birgit ; Alaei, Saeed LU ; Bengtson, Per LU ; Bodé, Samuel ; Boeckx, Pascal ; Schnecker, Jörg ; Mayerhofer, Werner and Rütting, Tobias
- organization
- publishing date
- 2017-12
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Ammonification, Boreal forest, Microbial N mining, N mineralization, Organic N, Priming, Protein depolymerization
- in
- Biogeochemistry
- volume
- 136
- issue
- 3
- pages
- 261 - 278
- publisher
- Springer
- external identifiers
-
- wos:000416325100003
- scopus:85032358644
- ISSN
- 0168-2563
- DOI
- 10.1007/s10533-017-0391-0
- language
- English
- LU publication?
- yes
- id
- fd8df779-510f-4a39-96d1-38280253dabc
- date added to LUP
- 2017-11-07 13:14:31
- date last changed
- 2024-04-14 21:50:57
@article{fd8df779-510f-4a39-96d1-38280253dabc,
abstract = {{<p>Rising carbon dioxide (CO<sub>2</sub>) concentrations and temperatures are expected to stimulate plant productivity and ecosystem C sequestration, but these effects require a concurrent increase in N availability for plants. Plants might indirectly promote N availability as they release organic C into the soil (e.g., by root exudation) that can increase microbial soil organic matter (SOM) decomposition (“priming effect”), and possibly the enzymatic breakdown of N-rich polymers, such as proteins, into bio-available units (“N mining”). We tested the adjustment of protein depolymerization to changing soil C and N availability in a laboratory experiment. We added easily available C or N sources to six boreal forest soils, and determined soil organic C mineralization, gross protein depolymerization and gross ammonification rates (using <sup>15</sup>N pool dilution assays), and potential extracellular enzyme activities after 1 week of incubation. Added C sources were <sup>13</sup>C-labelled to distinguish substrate from soil derived C mineralization. Observed effects reflect short-term adaptations of non-symbiotic soil microorganisms to increased C or N availability. Although C input promoted microbial growth and N demand, we did not find indicators of increased N mobilization from SOM polymers, given that none of the soils showed a significant increase in protein depolymerization, and only one soil showed a significant increase in N-targeting enzymes. Instead, our findings suggest that microorganisms immobilized the already available N more efficiently, as indicated by decreased ammonification and inorganic N concentrations. Likewise, although N input stimulated ammonification, we found no significant effect on protein depolymerization. Although our findings do not rule out in general that higher plant-soil C allocation can promote microbial N mining, they suggest that such an effect can be counteracted, at least in the short term, by increased microbial N immobilization, further aggravating plant N limitation.</p>}},
author = {{Wild, Birgit and Alaei, Saeed and Bengtson, Per and Bodé, Samuel and Boeckx, Pascal and Schnecker, Jörg and Mayerhofer, Werner and Rütting, Tobias}},
issn = {{0168-2563}},
keywords = {{Ammonification; Boreal forest; Microbial N mining; N mineralization; Organic N; Priming; Protein depolymerization}},
language = {{eng}},
number = {{3}},
pages = {{261--278}},
publisher = {{Springer}},
series = {{Biogeochemistry}},
title = {{Short-term carbon input increases microbial nitrogen demand, but not microbial nitrogen mining, in a set of boreal forest soils}},
url = {{http://dx.doi.org/10.1007/s10533-017-0391-0}},
doi = {{10.1007/s10533-017-0391-0}},
volume = {{136}},
year = {{2017}},
}