Details
| Original language | English |
|---|---|
| Pages (from-to) | 2627-2640 |
| Number of pages | 14 |
| Journal | BIOGEOSCIENCES |
| Volume | 14 |
| Issue number | 10 |
| Publication status | Published - 24 May 2017 |
Abstract
Macro-Aggregates especially in agricultural steppe soils are supposed to play a vital role for soil organic carbon (OC) stabilization at a decadal timescale. While most research on soil OC stabilization in steppes focused on North American prairie soils of the Great Plains with information mainly provided by short-Term incubation experiments, little is known about the agricultural steppes in southwestern Siberia, though they belong to the greatest conversion areas in the world and occupy an area larger than that in the Great Plains. To quantify the proportion of macro-Aggregate-protected OC under different land use as function of land use intensity and time since land use change (LUC) from pasture to arable land in Siberian steppe soils, we determined OC mineralization rates of intact (250-2000ĝ€μm) and crushed (<ĝ€250ĝ€μm) macro-Aggregates in long-Term incubations over 401 days (20ĝ€°C; 60ĝ€% water holding capacity) along two agricultural chronosequences in the Siberian Kulunda steppe. Additionally, we incubated bulk soil (<ĝ€2000ĝ€μm) to determine the effect of LUC and subsequent agricultural use on a fast and a slow soil OC pool (labile vs. more stable OC), as derived from fitting exponential-decay models to incubation data. We hypothesized that (i) macro-Aggregate crushing leads to increased OC mineralization due to an increasing microbial accessibility of a previously occluded labile macro-Aggregate OC fraction, and (ii) bulk soil OC mineralization rates and the size of the fast OC pool are higher in pasture than in arable soils with decreasing bulk soil OC mineralization rates and size of the fast OC pool as land use intensity and time since LUC increase. Against our hypothesis, OC mineralization rates of crushed macro-Aggregates were similar to those of intact macro-Aggregates under all land use regimes. Macro-Aggregate-protected OC was almost absent and accounted for <ĝ€1ĝ€% of the total macro-Aggregate OC content and to a maximum of 8ĝ€±ĝ€4ĝ€% of mineralized OC. In accordance to our second hypothesis, highest bulk soil OC mineralization rates and sizes of the fast OC pool were determined under pasture, but mineralization rates and pool sizes were unaffected by land use intensity and time since LUC. However, at one chronosequence mean residence times of the fast and slow OC pool tended to decrease with increasing time since establishment of arable use. We conclude that the tillage-induced breakdown of macro-Aggregates has not reduced the OC contents in the soils under study. The decline of OC after LUC is probably attributed to the faster soil OC turnover under arable land as compared to pasture at a reduced plant residue input.
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Ecology, Evolution, Behavior and Systematics
- Earth and Planetary Sciences(all)
- Earth-Surface Processes
Sustainable Development Goals
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In: BIOGEOSCIENCES, Vol. 14, No. 10, 24.05.2017, p. 2627-2640.
Research output: Contribution to journal › Article › Research › peer review
}
TY - JOUR
T1 - Limited protection of macro-Aggregate-occluded organic carbon in Siberian steppe soils
AU - Bischoff, Norbert
AU - Mikutta, Robert
AU - Shibistova, Olga
AU - Puzanov, Alexander
AU - Silanteva, Marina
AU - Grebennikova, Anna
AU - Fuß, Roland
AU - Guggenberger, Georg
PY - 2017/5/24
Y1 - 2017/5/24
N2 - Macro-Aggregates especially in agricultural steppe soils are supposed to play a vital role for soil organic carbon (OC) stabilization at a decadal timescale. While most research on soil OC stabilization in steppes focused on North American prairie soils of the Great Plains with information mainly provided by short-Term incubation experiments, little is known about the agricultural steppes in southwestern Siberia, though they belong to the greatest conversion areas in the world and occupy an area larger than that in the Great Plains. To quantify the proportion of macro-Aggregate-protected OC under different land use as function of land use intensity and time since land use change (LUC) from pasture to arable land in Siberian steppe soils, we determined OC mineralization rates of intact (250-2000ĝ€μm) and crushed (<ĝ€250ĝ€μm) macro-Aggregates in long-Term incubations over 401 days (20ĝ€°C; 60ĝ€% water holding capacity) along two agricultural chronosequences in the Siberian Kulunda steppe. Additionally, we incubated bulk soil (<ĝ€2000ĝ€μm) to determine the effect of LUC and subsequent agricultural use on a fast and a slow soil OC pool (labile vs. more stable OC), as derived from fitting exponential-decay models to incubation data. We hypothesized that (i) macro-Aggregate crushing leads to increased OC mineralization due to an increasing microbial accessibility of a previously occluded labile macro-Aggregate OC fraction, and (ii) bulk soil OC mineralization rates and the size of the fast OC pool are higher in pasture than in arable soils with decreasing bulk soil OC mineralization rates and size of the fast OC pool as land use intensity and time since LUC increase. Against our hypothesis, OC mineralization rates of crushed macro-Aggregates were similar to those of intact macro-Aggregates under all land use regimes. Macro-Aggregate-protected OC was almost absent and accounted for <ĝ€1ĝ€% of the total macro-Aggregate OC content and to a maximum of 8ĝ€±ĝ€4ĝ€% of mineralized OC. In accordance to our second hypothesis, highest bulk soil OC mineralization rates and sizes of the fast OC pool were determined under pasture, but mineralization rates and pool sizes were unaffected by land use intensity and time since LUC. However, at one chronosequence mean residence times of the fast and slow OC pool tended to decrease with increasing time since establishment of arable use. We conclude that the tillage-induced breakdown of macro-Aggregates has not reduced the OC contents in the soils under study. The decline of OC after LUC is probably attributed to the faster soil OC turnover under arable land as compared to pasture at a reduced plant residue input.
AB - Macro-Aggregates especially in agricultural steppe soils are supposed to play a vital role for soil organic carbon (OC) stabilization at a decadal timescale. While most research on soil OC stabilization in steppes focused on North American prairie soils of the Great Plains with information mainly provided by short-Term incubation experiments, little is known about the agricultural steppes in southwestern Siberia, though they belong to the greatest conversion areas in the world and occupy an area larger than that in the Great Plains. To quantify the proportion of macro-Aggregate-protected OC under different land use as function of land use intensity and time since land use change (LUC) from pasture to arable land in Siberian steppe soils, we determined OC mineralization rates of intact (250-2000ĝ€μm) and crushed (<ĝ€250ĝ€μm) macro-Aggregates in long-Term incubations over 401 days (20ĝ€°C; 60ĝ€% water holding capacity) along two agricultural chronosequences in the Siberian Kulunda steppe. Additionally, we incubated bulk soil (<ĝ€2000ĝ€μm) to determine the effect of LUC and subsequent agricultural use on a fast and a slow soil OC pool (labile vs. more stable OC), as derived from fitting exponential-decay models to incubation data. We hypothesized that (i) macro-Aggregate crushing leads to increased OC mineralization due to an increasing microbial accessibility of a previously occluded labile macro-Aggregate OC fraction, and (ii) bulk soil OC mineralization rates and the size of the fast OC pool are higher in pasture than in arable soils with decreasing bulk soil OC mineralization rates and size of the fast OC pool as land use intensity and time since LUC increase. Against our hypothesis, OC mineralization rates of crushed macro-Aggregates were similar to those of intact macro-Aggregates under all land use regimes. Macro-Aggregate-protected OC was almost absent and accounted for <ĝ€1ĝ€% of the total macro-Aggregate OC content and to a maximum of 8ĝ€±ĝ€4ĝ€% of mineralized OC. In accordance to our second hypothesis, highest bulk soil OC mineralization rates and sizes of the fast OC pool were determined under pasture, but mineralization rates and pool sizes were unaffected by land use intensity and time since LUC. However, at one chronosequence mean residence times of the fast and slow OC pool tended to decrease with increasing time since establishment of arable use. We conclude that the tillage-induced breakdown of macro-Aggregates has not reduced the OC contents in the soils under study. The decline of OC after LUC is probably attributed to the faster soil OC turnover under arable land as compared to pasture at a reduced plant residue input.
UR - http://www.scopus.com/inward/record.url?scp=85019755829&partnerID=8YFLogxK
U2 - 10.5194/bg-14-2627-2017
DO - 10.5194/bg-14-2627-2017
M3 - Article
AN - SCOPUS:85019755829
VL - 14
SP - 2627
EP - 2640
JO - BIOGEOSCIENCES
JF - BIOGEOSCIENCES
SN - 1726-4170
IS - 10
ER -