Effects of drying/rewetting on soil aggregate dynamics and implications for organic matter turnover
Author
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Najera De Ferrari, Francisco
Author
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Dippold, Michaela A.
Author
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Boy, Jens
Author
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Seguel Seguel, Óscar
Author
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Koester, Moritz
Author
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Stock, Svenja
Author
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Merino, Carolina
Author
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Kuzyakov, Yakov
Author
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Matus, Francisco
Admission date
dc.date.accessioned
2020-06-15T21:48:08Z
Available date
dc.date.available
2020-06-15T21:48:08Z
Publication date
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2020
Cita de ítem
dc.identifier.citation
Biology and Fertility of Soils (2020)
es_ES
Identifier
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10.1007/s00374-020-01469-6
Identifier
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https://repositorio.uchile.cl/handle/2250/175468
Abstract
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Drying and rewetting (D/W) of soil have significant impacts on soil organic matter (SOM) turnover. We hypothesised that frequent D/W cycles would release the labile organic matter locked away in soil aggregates, increasing the priming effect (PE) (acceleration or retardation of SOM turnover after fresh substrate addition) due to preferential utilisation by microbes. C-13-labelled lignocellulose was added to the soil, and the effects of 0, 1, or 4 cycles of D/W were evaluated at 5 degrees C and 25 degrees C after a 27-day incubation of undisturbed soil cores from a temperate forest (Araucaria araucana). Following the incubation, macroaggregates (> 250 mu m), microaggregates (250-53 mu m), and silt + clay materials (< 53 mu m) were separated. For each aggregate size class, three organic matter (OM) fractions (light (fPOM < 1.6 g cm(-3)), occluded (oPOM 1.6-2.0 g cm(-3)), and heavy (Hf > 2.0 g cm(-3)) were determined. D/W cycles caused macroaggregates to increase and a decrease in microaggregates (> 15%) at warm temperatures, and preferential use of the novel particulate organic matter (C-13 labelled), formerly protected fPOM. CO2 efflux was three times higher at 25 degrees C than at 5 degrees C. The D/W cycles at 25 degrees C had a strong negative impact on cumulative CO2 efflux, which decreased by approximately - 30%, induced by a negative PE of -50 mg C kg(-1) soil with 1 D/W cycle and - 100 mg C kg(-1) soil with 4 D/W cycles, relative to soil under constant soil moisture receiving C-13-labelled lignocellulose, but no cycles. Increasing the temperature and the number of D/W cycles caused a decrease in substrate use efficiency of particulate lignocellulose. In conclusion, D/W cycles at warm temperatures accelerated OM turnover due to preferential use from fPOM, increasing macroaggregates at the expense of microaggregates. A novel pathway of OM release and PE due to the D/W cycles is discussed.
es_ES
Patrocinador
dc.description.sponsorship
German Research Foundation (DFG) SPP-1803 KU 1184/36-1
CONICYT of Chilean government 21160957
National Commission of Research of Science and Technology FONDECYT 1170119
Network for Extreme Environmental Research (NEXER), Universidad de La Frontera