Little effects on soil organic matter chemistry of density fractions after seven years of forest soil warming

There is an obvious difference in δ13C values between plants that assimilate carbon via the C3 photosynthetic pathway and those that do so by the C4 photosynthetic pathway. In terms of this characteristic, we analysed the organic carbon content and δ13C values of total soil and δ13C values in different size and density fractions of profile-soil samples either in farmland or in forestland near the Maolan Karst virgin forest, south-west China. This is an area where C3 plants grew previously, now replaced by C4 plants. Deforestation has accelerated the decomposition rate of soil organic matter and reduced the proportion of active components in soil organic matter and thus soil fertility. The δ13C values of different size fractions in forest soil are δ13Ccoarse sand < δ13Cfine sand < δ13Ccoarse silt < δ13Cclay < δ13Cfine silt, and the δ13C values of different size fractions in farmland soil are δ13Ccoarse sand > δ13Cfine sand > δ13Ccoarse silt > δ13Cclay > δ13Cfine silt, indicating that soil organic matter is fresh in coarse sand and oldest in fine silt. The δ13C values of different density fractions in forest soil are δ13Clight < δ13Cheavy, and the δ13C values of different density fractions in farmland soil are δ13Clight > δ13Cheavy, indicating that the soil organic matter is fresh in light fractions and old in heavy fractions.

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Warming-enhanced preferential microbial mineralization of humified boreal forest soil organic matter: Interpretation of soil profiles along a climate transect using laboratory incubations

Journal of Geophysical Research Atmospheres ◽

10.1029/2011jg001769 ◽

2012 ◽

Vol 117 (G2) ◽

pp. n/a-n/a ◽

Cited By ~ 12

Author(s):

Jianwei Li ◽

Susan Ziegler ◽

Chad S. Lane ◽

Sharon A. Billings

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Boreal Forest ◽

Forest Soil ◽

Soil Profiles ◽

Forest Soil Organic Matter ◽

Microbial Mineralization

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Net nitrogen mineralization from light- and heavy-fraction forest soil organic matter

Soil Biology and Biochemistry ◽

10.1016/0038-0717(84)90122-6 ◽

1984 ◽

Vol 16 (1) ◽

pp. 31-37 ◽

Cited By ~ 199

Author(s):

P. Sollins ◽

G. Spycher ◽

C.A. Glassman

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Forest Soil ◽

Nitrogen Mineralization ◽

Heavy Fraction ◽

Net Nitrogen Mineralization ◽

Forest Soil Organic Matter

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Examining mineral-associated soil organic matter pools through depth in harvested forest soil profiles

PLoS ONE ◽

10.1371/journal.pone.0206847 ◽

2018 ◽

Vol 13 (11) ◽

pp. e0206847 ◽

Cited By ~ 2

Author(s):

C. E. Gabriel ◽

L. Kellman ◽

D. Prest

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Forest Soil ◽

Soil Profiles

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Effect of systematic application of mineral fertilizers and long-term aftereffect of liming on the organic matter of light-grey forest soil

Agricultural science Euro-North-East ◽

10.30766/2072-9081.2020.21.2.160-168 ◽

2020 ◽

Vol 21 (2) ◽

pp. 160-168

Author(s):

N. A. Kodochilova ◽

T. S. Buzynina ◽

L. D. Varlamova ◽

E. A. Katerova

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Forest Soil ◽

Humus Content ◽

Total Carbon ◽

Mineral Fertilizers ◽

Fertilized Soil ◽

Grey Forest Soil ◽

Nizhny Novgorod Region

The studies on assessment of changes in the content and composition of soil organic matter under the influence of the systematic use of mineral fertilizers (NPK)1, (NPK)2, (NPK)3 against the background of the aftereffect of single liming in doses of 1.0 and 2.0 h. a. (control – variants without fertilizers and lime) were conducted in the conditions of the Nizhny Novgorod region in a long – term stationary experiment on light-grey forest soil. The research was carried out upon comple-tion of the fifth rotation of the eight-field crop rotation. The results of the study showed that for 40 years (from 1978 to 2018) the humus content in the soil (0-20 cm) decreased by 0.19-0.52 abs. % in variants as compared to the original (1.60 %); though, humus mineralization was less evident against the background of long-term use of mineral fertilizers compared to non-fertilized control. The higher humus content in the topsoil was noted in the variants with minimal (NPK)1 and increased (NPK)2 doses of fertilizer – 1.41 and 1.25 %, respectively. The humus content in non-fertilized soil and when applying high (NPK)3 doses of mineral fertilizers was almost identical – 1.08-1.09 %. The predominant group in the composition of humus were humic acids, the content of which in the experiment on average was 37.8 % of the total carbon with an evident decrease from 42.6 % in the control to 31.8% when applying increased doses of mineral fertilizers. The aftereffect of liming, carried out in 1978, was unstable and did not significantly affect the content and composition of soil organic matter.

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Thermal fractionation of soil organic matter produces fine-scale distributions of SOM age

10.5194/egusphere-egu21-15968 ◽

2021 ◽

Author(s):

Shane Stoner ◽

Carlos Sierra ◽

Marion Schrumpf ◽

Sebastian Dötterl ◽

Susan Trumbore

Keyword(s):

Thermal Stability ◽

Organic Matter ◽

Soil Organic Matter ◽

Chemical Oxidation ◽

Fine Scale ◽

Mineral Association ◽

Density Fractions ◽

Chemical Complexity ◽

Wide Range ◽

Carbon Release

Soil organic matter (SOM) is a complex collection of organic molecules of varying origin, structure, chemical activity, and mineral association. A wide array of laboratory methods exists to separate SOM based on qualitative, biological, chemical, and physical characteristics. However, all present conceptual and logistical limitations, including the requirement of a substantial amount soil material.An newly applied alternative method of fractionation relies on a conceptual analogue between biochemical stability in soil and thermal stability, e.g. more persistent SOM will require higher temperatures (greater energy inputs) to decompose than less persistent SOM. This accounts for both chemical complexity and mineral association as main factors in determining SOM persistence.In this method, carbon is released by heating SOM to 900&#176;C at a constant rate. The peaks of carbon release are grouped into activation energy pools, CO2 is collected, and analyzed for 13C and 14C. We seek to describe in finer detail the distribution of soil radiocarbon by adding another fractionation step following a different paradigm of SOM stability, and explore mineralogical effects on SOM quality and stability using thermal analysis, radiocarbon, and gas chromatography.Here, we analyzed bulk soil and soil fractions derived from density separation and chemical oxidation, as well as mineral horizons dominated by diverse mineralogies. Density fractions contained a wide range of radiocarbon activities and that young SOM is stabilized across multiple fractions, likely due to organomineral complexation. Initial results showed that soil minerals with limited stabilization potential released C at lower temperatures than those with diverse stabilization mechanisms. High-temperature sub-fractions contained the oldest carbon across fractions and minerals, thus supporting the assumption that thermal stability can be used as a limited analogue for stability in soil. We present a fine-scale distribution of radiocarbon in SOM and discuss the potential of this method for comparison with other fractionation techniques.

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Correction to: Changes in forest soil organic matter quality affected by windstorm and wildfire

Journal of Soils and Sediments ◽

10.1007/s11368-018-1979-2 ◽

2018 ◽

Vol 18 (8) ◽

pp. 2748-2748 ◽

Cited By ~ 1

Author(s):

Gabriela Barančíková ◽

Maria Jerzykiewicz ◽

Erika Gömöryová ◽

Erika Tobiašová ◽

Tadeáš Litavec

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Forest Soil ◽

Organic Matter Quality ◽

Forest Soil Organic Matter ◽

Soil Organic Matter Quality

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Strong warming of subarctic forest soil deteriorated soil structure via carbon loss – Indications from organic matter fractionation

10.5194/soil-2019-41 ◽

2019 ◽

Author(s):

Christopher Poeplau ◽

Páll Sigurðsson ◽

Bjarni D. Sigurðsson

Keyword(s):

Organic Matter ◽

Forest Soil ◽

Soil Structure ◽

Terrestrial Ecosystems ◽

Soil Mass ◽

Soil Warming ◽

Ecosystem Responses ◽

Structure Changes ◽

Northern Latitudes ◽

Fraction Distribution

Abstract. Net loss of soil organic carbon (SOC) from terrestrial ecosystems is a likely consequence of global warming and this may affect key soil functions. Strongest changes in temperature are expected to occur at high northern latitudes, with boreal forest and tundra as prevailing land-cover types. However, specific ecosystem responses to warming are understudied. We used a natural geothermal soil warming gradient in an Icelandic spruce forest (0–17.5 °C warming intensity) to assess changes in SOC content in 0–10 cm (topsoil) and 20–30 cm (subsoil) after 10 years of soil warming. Five different SOC fractions were isolated and the amount of stable aggregates (63–2000 µm) was assessed to link SOC to soil structure changes. Results were compared to an adjacent, previously investigated warmed grassland. Soil warming had depleted SOC in the forest soil by −2.7 g kg−1 °C−1 (−3.6 % °C−1) in the topsoil and −1.6 g kg−1 °C−1 (−4.5 % °C−1) in the subsoil. Distribution of SOC in different fractions was significantly altered, with particulate organic matter and SOC in sand and stable aggregates being relatively depleted and SOC attached to silt and clay being relatively enriched in warmed soils. The major reason for this shift was aggregate break-down: topsoil aggregate mass proportion was reduced from 60.7 ± 2.2 % in the unwarmed reference to 28.9 ± 4.6 % in the most warmed soil. Across both depths, loss of one unit SOC caused a depletion of 4.5 units aggregated soil, which strongly affected bulk density (R2 = 0.91 when correlated to SOC and R2 = 0.51 when correlated to soil mass in stable aggregates). The proportion of water extractable carbon increased with decreasing aggregation, indicating an indirect SOC protective effect of aggregates > 63 µm. Topsoil changes in total SOC and fraction distribution were more pronounced in the forest than in the adjacent warmed grassland soils, due to higher and more labile initial SOC. However, no ecosystem effect was observed in the response of subsoil SOC and fraction distribution. Whole profile differences across ecosystems might thus be small. Changes in soil structure upon warming should be studied more deeply and taken into consideration when interpreting or modelling biotic responses to warming.

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