Radiocarbon Dating for Determination of Soil Organic Matter Pool Sizes and Dynamics

Paul, Eldor A.; Follett, R. F.; Leavitt, Steven W.; Halvorson, Ardell D.; Peterson, G. A.; Lyon, Drew J.

doi:10.2136/sssaj1997.03615995006100040011x

Cited by 335 publications

(215 citation statements)

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“…Below 20 cm soil depth, humic acids yield 14 C values <100 pMC which suggests a small proportion of C derived from recent plant inputs . A considerable decrease in 14 C with increasing soil depth of 30% to 54% was observed for the humin fraction with increasing depth in the profile, similar to earlier observations by Paul et al (1997). This indicates both, a low contribution of young compounds and a relative enrichment of stabilized organic components in the humin fraction with soil depth.…”

Section: Chemical Som Fractionssupporting

confidence: 88%

How relevant is recalcitrance for the stabilization of organic matter in soils?

Marschner

Brodowski

Dreves

et al. 2008

Z. Pflanzenernähr. Bodenk.

626

359

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Traditionally, the selective preservation of certain recalcitrant organic compounds and the formation of recalcitrant humic substances have been regarded as an important mechanism for soil organic matter (SOM) stabilization. Based on a critical overview of available methods and on results from a cooperative research program, this paper evaluates how relevant recalcitrance is for the long-term stabilization of SOM or its fractions. Methodologically, recalcitrance is difficult to assess, since the persistence of certain SOM fractions or specific compounds may also be caused by other stabilization mechanisms, such as physical protection or chemical interactions with mineral surfaces. If only free particulate SOM obtained from density fractionation is considered, it rarely reaches ages exceeding 50 y. Older light particles have often been identified as charred plant residues or as fossil C. The degradability of the readily bioavailable dissolved or water-extractable OM fraction is often negatively correlated with its content in aromatic compounds, which therefore has been associated with recalcitrance. But in subsoils, dissolved organic matter aromaticity and biodegradability both are very low, indicating that other factors or compounds limit its degradation. Among the investigated specific compounds, lignin, lipids, and their derivatives have mean turnover times faster or similar as that of bulk SOM. Only a small fraction of the lignin inputs seems to persist in soils and is mainly found in the fine textural size fraction (<20 lm), indicating physico-chemical stabilization. Compound-specific analysis of 13 C : 12 C ratios of SOM pyrolysis products in soils with C3-C4 crop changes revealed no compounds with mean residence times of > 40-50 y, unless fossil C was present in substantial amounts, as at a site exposed to lignite inputs in the past. Here, turnover of pyrolysis products seemed to be much longer, even for those attributed to carbohydrates or proteins. Apparently, fossil C from lignite coal is also utilized by soil organisms, which is further evidenced by low 14 C concentrations in microbial phospholipid fatty acids from this site. Also, black C from charred plant materials was susceptible to microbial degradation in a short-term (60 d) and a long-term (2 y) incubation

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Section: Chemical Som Fractionssupporting

confidence: 88%

How relevant is recalcitrance for the stabilization of organic matter in soils?

Marschner

Brodowski

Dreves

et al. 2008

Z. Pflanzenernähr. Bodenk.

626

359

View full text Add to dashboard Cite

show abstract

“…Investigations into the soil organic matter (SOM) grain size fractions have been undertaken to better appreciate the contribution of carbon fractions to 14 C age determinations (Gillespie et al 1992;Trumbore 1993;Bol et al 1996;Leavitt et al 1996;Paul et al 1997). Acid hydrolysis, humus fractionation, density separation, and size separation are all examples of methods that have been employed to isolate and date certain components of SOM.…”

Section: Discussionmentioning

confidence: 99%

Preliminary ¹⁴C Dates on Bulk Soil Organic Matter from the Black Creek Megafauna Fossil Site, Rocky River, Kangaroo Island, South Australia

2004

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Radiocarbon age determinations and stratigraphy suggest that the deposits in Black Creek Swamp on Kangaroo Island record 3 phases of deposition and associated soil development which spanned at least the last 20,000 yr. Four new 14C age determinations on bulk soil organic matter and their stratigraphic context are presented in this paper. Three of these age determinations (FP6: 15,687 ± 110 BP [WK11487]; FP7: 16,326 ± 385 BP [WK11488]; and FP8: 17,618 ± 447 BP [WK11489]), are from the organic-rich fossil layer located 45–75 cm below the current floodplain surface. The fourth, a much younger date, FP5: 5589 ± 259 BP (WK11486), was obtained from the base of the overlying modern soil. The dates for the fossil layer increase systematically with depth and correlate well with 5 previous 14C dates (Hope et al., unpublished), ranging between 15,040 ± 120 BP and 19,000 ± 310 BP. This suggests that the data set represents a possible minimum age of the bulk organic matter, and considering the high organic matter contents of approximately 8%, has implications for the age of the megafauna buried in this layer. The overlying modern soil, with its much younger date, contains lower levels of organic matter (3–7%) and gastropods not seen in the fossil layer. This suggests a substantial change in environmental conditions probably due to an alteration in the floodplain drainage conditions. This chronological and sedimentalogical discontinuity indicates that 2 distinct depositional regimes existed and were separated by up to 10,000 14C yr. A calcareous, sandy silt deposit underlying the fossil layer is a calcarenite deposit with low total organic content and is considered the base of the section; it suggests a third separate depositional episode. As such, the Black Creek Swamp in the southwest corner of Kangaroo Island formed intermittently over at least the last 20,000 yr during 3 distinct depositional phases, one of which was the formation of the fossil-laden, organic-rich floodplain surface, which has a possible minimum age of approximately 15,000 to 19,000 BP.

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“…We compare deep soil carbon stock and soil 14 C inventories, the first such to be published for four of these sites (Gaudinski et al 2000 reports soil carbon dynamics at Harvard Forest). In addition to the bulk soil inventory, we provide a more detailed analysis of SOM near the surface (top 15 cm), where the most dynamic soil carbon pools are found (Paul et al 1997;Trumbore et al 1996). We also compare carbon distribution and 14 C-based turnover times of surface soil density fractions amongst our five sites.…”

Section: Introductionmentioning

confidence: 99%

Comparison of soil organic matter dynamics at five temperate deciduous forests with physical fractionation and radiocarbon measurements

et al. 2012

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Forest soils represent a significant pool for carbon sequestration and storage, but the factors controlling soil carbon cycling are not well constrained. We compared soil carbon dynamics at five broadleaf forests in the Eastern US that vary in climate, soil type, and soil ecology: two sites at the University of Michigan Biological Station (MI-Coarse, sandy; MI-Fine, loamy); Bartlett Experimental Forest (NH-BF); Harvard Forest (MA-HF); and Baskett Wildlife Recreation and Education Area (MO-OZ). We quantified soil carbon stocks and measured bulk soil radiocarbon to at least 60 cm depth. We determined surface (0-15 cm) soil carbon distribution and turnover times in free light (unprotected), occluded light (intra-aggregate), and dense (mineral-associated) soil fractions. Total soil carbon stocks ranged from 55 ± 4 to 229 ± 42 Mg C ha -1 and were lowest at MI-Coarse and MO-OZ and highest at MI-Fine and NH-BF. Differences in climate only partly explained differences in soil organic matter 14 C and mean turnover times, which were 75-260 year for free-light fractions, 70-625 year for occluded-light fractions, and 90-480 year for dense fractions. Turnover times were shortest at the warmest site, but longest at the northeastern sites (NH-BF and MA-HF), rather than the coldest sites (MI-Coarse and MI-Fine). Soil texture, mineralogy, drainage, and macrofaunal activity may be at least as important as climate in determining soil carbon dynamics in temperate broadleaf forests.

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Radiocarbon Dating for Determination of Soil Organic Matter Pool Sizes and Dynamics

Abstract: ABSTRACT

Cited by 335 publications

References 0 publications

How relevant is recalcitrance for the stabilization of organic matter in soils?

How relevant is recalcitrance for the stabilization of organic matter in soils?

Preliminary ¹⁴C Dates on Bulk Soil Organic Matter from the Black Creek Megafauna Fossil Site, Rocky River, Kangaroo Island, South Australia

Comparison of soil organic matter dynamics at five temperate deciduous forests with physical fractionation and radiocarbon measurements

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Radiocarbon Dating for Determination of Soil Organic Matter Pool Sizes and Dynamics

Abstract: ABSTRACT

Cited by 335 publications

References 0 publications

How relevant is recalcitrance for the stabilization of organic matter in soils?

How relevant is recalcitrance for the stabilization of organic matter in soils?

Preliminary 14C Dates on Bulk Soil Organic Matter from the Black Creek Megafauna Fossil Site, Rocky River, Kangaroo Island, South Australia

Comparison of soil organic matter dynamics at five temperate deciduous forests with physical fractionation and radiocarbon measurements

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Preliminary ¹⁴C Dates on Bulk Soil Organic Matter from the Black Creek Megafauna Fossil Site, Rocky River, Kangaroo Island, South Australia