Dynamics of soil organic matter in a cultivated chronosequence in the Cerrado (Minas Gerais, Brazil)

The vegetation of the Cerrado has been replaced by pastures and agriculture, affecting the stock and dynamic of soil organic matter (SOM). The present study was conducted in a cultivated chronosequence with a mixed system (agriculture+pasture for 15 years; Agric+P15) and cultivated pasture (30 years; P30), taking the native Cerrado as a reference to assess changes in the stock of SOM, the dynamics (δ13C) and the carbon replacement derived from the C3 in native vegetation to C4 in cultivated vegetation. Compared to Cerrado, there was a reduction in C stock in cultivated soils at 0–15-cm depth (reduction of 26.5% in Agri+P15 and 6% in P30). The close similarity between Cerrado and P30 indicates that the pasture management enhanced the stock relative to Agri+P15, but was not effective in sequestering C. Only in the 0–15cm depth was there a marked replacement of C derived from the C3 of Cerrado plants associated with cultivation time. In the chronosequence, the isotopic signature of C4 plants dominated in the soil below 30cm depth, suggesting a paleoclimatic effect on SOM.

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Molecular characterization of soil organic matter from native vegetation–pasture–sugarcane transitions in Brazil

The Science of The Total Environment ◽

10.1016/j.scitotenv.2016.01.039 ◽

2016 ◽

Vol 548-549 ◽

pp. 450-462 ◽

Cited By ~ 13

Author(s):

Dener Márcio da Silva Oliveira ◽

Judith Schellekens ◽

Carlos Eduardo Pellegrino Cerri

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Molecular Characterization ◽

Native Vegetation

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Contributions of carbonates to soil CO2 emissions

Canadian Journal of Soil Science ◽

10.4141/cjss2011-025 ◽

2012 ◽

Vol 92 (4) ◽

pp. 599-607 ◽

Cited By ~ 36

Author(s):

R. Ramnarine ◽

C. Wagner-Riddle ◽

K. E. Dunfield ◽

R. P. Voroney

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Inorganic Carbon ◽

Calcareous Soils ◽

Decomposition Analysis ◽

Isotope Ratio Mass Spectrometry ◽

Conventional Tillage ◽

Isotopic Signature ◽

Soil Samples ◽

Soil Carbonates

Ramnarine, R., Wagner-Riddle, C., Dunfield, K. E. and Voroney, R. P. 2012. Contributions of carbonates to soil CO 2 emissions. Can. J. Soil Sci. 92: 599–607. Carbon dioxide (CO2) is released in soil as a by-product of microbial and root respiration, but soil carbonates may also be a source of CO2 emissions in calcareous soils. Global estimates of inorganic carbon range from 700 to 900 Pg as carbonates stored in soils, representing a significant potential source of CO2 to the atmosphere. While previous studies have focused on the total CO2 efflux from the soil, our goal was to identify the various sources and their contribution to total CO2 emissions, by measuring the isotopic signature of the CO2 emitted from the soil. Calcareous Luvisolic silt loam soil samples were obtained from conventional tillage (CT) and no-tillage (NT) plots in southern Ontario, Canada. Soil samples (root- and residue-free) were laboratory-incubated for 14 d and the isotopic signature of the CO2 (δ13CCO2) released was analyzed using isotope ratio mass spectrometry. Isotopic measurement was essential in quantifying the abiotic CO2 production from carbonates, due to the unique δ13C signature of carbonates and soil organic matter. A two-end member mixing model was used to estimate the proportion of CO2 evolved from soil carbonates and soil organic matter decomposition. Analysis of emitted CO2 collected after the 14-d incubation indicate that the proportion of CO2 originating from soil inorganic carbon was 62 to 74% for CT soil samples, and 64 to 80% for NT soil samples. Further work is recommended in the quantification of CO2 emissions from calcareous soils, and to determine the transferability of laboratory results to field studies.

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Hydrogen dynamics in soil organic matter as determined by 13C and 2H labeling experiments

10.5194/bg-2016-317 ◽

2016 ◽

Author(s):

Alexia Paul ◽

Christine Hatté ◽

Lucie Pastor ◽

Yves Thiry ◽

Françoise Siclet ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Isotopic Composition ◽

Bulk Material ◽

Isotopic Signature ◽

Close Link ◽

Carbon Cycles ◽

Exchangeable Hydrogen ◽

Terrestrial Environments ◽

Water Hydrogen

Abstract. Understanding hydrogen dynamics in soil organic matter is important to predict the fate of 3H in terrestrial environments. One way to resolve hydrogen fate and to point out processes is to examine the isotopic signature of the element in soil. However, non-exchangeable hydrogen isotopic signal in soil is complex and depends on the fate of organic compounds and microbial biosyntheses that incorporate water-derived hydrogen. To decipher this complex system and to understand the close link between hydrogen and carbon cycles, we followed labeled hydrogen and labeled carbon all along natural-like soil incubations. We performed incubation experiments with three labeling conditions: 1- 13C2H double-labeled molecules in the presence of 1H2O, 2- 13C-labeled molecules in the presence of 2H2O, 3- no molecule addition in the presence of 2H2O. The preservation of substrate-derived hydrogen after one year of incubation (ca. 5 % in most cases) was lower than the preservation of substrate-derived carbon (30 % in average). We highlighted that 70 % of the C-H bonds are broken during the degradation of the molecule which permits the exchange with water hydrogen. Added molecules are used more for trophic resources. The isotopic composition of the non-exchangeable hydrogen was mainly driven by the incorporation of water hydrogen during microbial biosynthesis. It is linearly correlated with the amount of carbon that is degraded in the soil. The quantitative incorporation of water hydrogen in bulk material and lipids demonstrates that non-exchangeable hydrogen exists in both organic and mineral-bound forms. The proportion of the latter depends on soil type and minerals. This experiment quantified the processes affecting the isotopic composition of non-exchangeable hydrogen, and the results can be used to predict the fate of tritium in the ecosystem or the water deuterium signature in organic matter.

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Soil carbon stocks cultivated with coffee in the brazilian savana: Effect of cultivation time and use of organic compost

Coffee Science ◽

10.25186/cs.v13i1.1366 ◽

2018 ◽

Vol 13 (1) ◽

pp. 53

Author(s):

Maísa Honório Belizário ◽

Gregori Da Encarnação Ferrão ◽

Carlos Clemente Cerri ◽

Marcos Siqueira Neto

Keyword(s):

Accumulation Rate ◽

Native Vegetation ◽

Soil C ◽

Cultivation Time ◽

C Stocks ◽

Soil Carbon Stocks ◽

C Stock ◽

Red Latosol ◽

Coffee Cultivation ◽

Organic Compost

Land-use change (LUC) is one of the main responsible for the loss of soil organic matter (SOM) in the form of CO2 to atmosphere. The aims of the present study were i) evaluate soil C stocks due to coffee cultivation time after LUC and ii) evaluate the use of the organic compost from the by-product of bean processing as a source of SOM. The study was performed in dystrophic red latosol in the municipality of Patrocínio, MG, Brazil. Two evaluations were performed; i) three coffee (Coffea arabica L. var. Icatú Vermelho) growing areas with different implantation times (8, 15 and 37 years) in relation to Cerrado stricto sensu (reference); and ii) area cultivated with coffee ( C. arabica var. Bourbon Vermelho) that received organic compost for four years. Soil was sampled in layers 0-5, 5-10 and 10-20 cm. In the first study, the C stock (0-20 cm) was higher under native vegetation (67 Mg C ha-1) in relation to the coffee growing (63 Mg C ha-1), however, did not differ significantly and showed subtle loss rates of 0.12; 0.06 and 0.02 Mg C ha-1 year-1 for 8, 15 and 37 years, respectively. In the second study, the organic compost applied to the soil increased the C stock (0-20 cm) to 4.6 Mg C ha-1 and showed an accumulation rate of 1.15 Mg C ha-1 year-1. Thus, it is concluded that C stocks is reduced in the soil due to LUC, however, the application of organic compost increased the supply of organic material, favoring the maintenance and even increasing the stock in the soil.

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Hydrogen dynamics in soil organic matter as determined by 13C and 2H labeling experiments

Biogeosciences ◽

10.5194/bg-13-6587-2016 ◽

2016 ◽

Vol 13 (24) ◽

pp. 6587-6598 ◽

Cited By ~ 4

Author(s):

Alexia Paul ◽

Christine Hatté ◽

Lucie Pastor ◽

Yves Thiry ◽

Françoise Siclet ◽

...

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Isotopic Composition ◽

Bulk Material ◽

Isotopic Signature ◽

Natural Soil ◽

Close Link ◽

Exchangeable Hydrogen ◽

Terrestrial Environments ◽

Water Hydrogen

Abstract. Understanding hydrogen dynamics in soil organic matter is important to predict the fate of 3H in terrestrial environments. One way to determine hydrogen fate and to point out processes is to examine the isotopic signature of the element in soil. However, the non-exchangeable hydrogen isotopic signal in soil is complex and depends on the fate of organic compounds and microbial biosyntheses that incorporate water-derived hydrogen. To decipher this complex system and to understand the close link between hydrogen and carbon cycles, we followed labeled hydrogen and labeled carbon throughout near-natural soil incubations. We performed incubation experiments with three labeling conditions: 1 – 13C2H double-labeled molecules in the presence of 1H2O; 2 – 13C-labeled molecules in the presence of 2H2O; 3 – no molecule addition in the presence of 2H2O. The preservation of substrate-derived hydrogen after 1 year of incubation (ca. 5 % in most cases) was lower than the preservation of substrate-derived carbon (30 % in average). We highlighted that 70 % of the C–H bonds are broken during the degradation of the molecule, which permits the exchange with water hydrogen. Added molecules are used more for trophic resources. The isotopic composition of the non-exchangeable hydrogen was mainly driven by the incorporation of water hydrogen during microbial biosynthesis. It is linearly correlated with the amount of carbon that is degraded in the soil. The quantitative incorporation of water hydrogen in bulk material and lipids demonstrates that non-exchangeable hydrogen exists in both organic and mineral-bound forms. The proportion of the latter depends on soil type and minerals. This experiment quantified the processes affecting the isotopic composition of non-exchangeable hydrogen, and the results can be used to predict the fate of tritium in the ecosystem or the water deuterium signature in organic matter.

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Aridity-driven decoupling of δ13C between pedogenic carbonate and soil organic matter

Geology ◽

10.1130/g47241.1 ◽

2020 ◽

Vol 48 (10) ◽

pp. 981-985 ◽

Cited By ~ 2

Author(s):

Jiawei Da ◽

Yi Ge Zhang ◽

Gen Li ◽

Junfeng Ji

Keyword(s):

Organic Matter ◽

Soil Organic Matter ◽

Pore Space ◽

C4 Plants ◽

Atmospheric Co2 ◽

Chinese Loess Plateau ◽

Pedogenic Carbonate ◽

Chinese Loess ◽

Pedogenic Carbonates ◽

Soil Pore Space

Abstract Pedogenic carbonate is an invaluable archive for reconstructing continental paleoclimate and paleoecology. The δ13C of pedogenic carbonate (δ13Cc) has been widely used to document the rise and expansion of C4 plants over the Cenozoic. This application requires a fundamental presumption that in soil pores, soil-respired CO2 dominates over atmospheric CO2 during the formation of pedogenic carbonates. However, the decoupling between δ13Cc and δ13C of soil organic matter (δ13CSOM) have been observed, particularly in arid regions, suggesting that this presumption is not always valid. To evaluate the influence of atmospheric CO2 on soil δ13Cc, here we performed systematic δ13C analyses of paleosols across the Chinese Loess Plateau, with the sample ages spanning three intervals: the Holocene, the Late Pleistocene, and the mid-Pliocene warm period. Our paired δ13Cc and δ13CSOM data reveal broadly divergent trending patterns. Using a two-component CO2-mixing model, we show substantial incorporations of atmospheric CO2 (up to 60%) into soil pore space during carbonate precipitation. This result readily explains the enrichment of δ13Cc and its divergence from δ13CSOM. As a consequence, δ13C of pedogenic carbonates formed under semiarid and/or arid conditions are largely driven by regional aridity through its control on soil CO2 composition, and thus cannot be used to evaluate the relative abundance of C3 versus C4 plants. Nonetheless, these carbonates can be applied for atmospheric CO2 reconstructions, even for periods with low CO2 levels.

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Oxidizable fraction of organic carbon in an Argisol under different land use systems

CERNE ◽

10.1590/s0104-77602012000200005 ◽

2012 ◽

Vol 18 (2) ◽

pp. 215-222 ◽

Cited By ~ 4

Author(s):

Caio Batista Müller ◽

Oscarlina Lúcia dos Santos Weber ◽

José Fernando Scaramuzza

Keyword(s):

Land Use ◽

Organic Matter ◽

Soil Organic Matter ◽

Organic Carbon ◽

The Other ◽

Control Treatment ◽

Native Vegetation ◽

Labile Carbon ◽

Land Use Systems ◽

Oxidizable Fraction

The objective of this study was to evaluate carbon input in labile and stable fractions in an ARGISOL of northwestern Brazil under different land use systems. Use systems being evaluated include: forest - MA (reference), agrosilvopasture - TCP (teak, cocoa and pasture); agroforest - TC (teak and cocoa); teak forest at 8 and 5 years - T8 and T5, and pasture - PA. In each system three furrows were made at depths of 0-5 cm, 5-10 cm and 10-20 cm. An area consisting of native vegetation (forest) adjacent to the experiment was sampled and used as control treatment. The use systems MA, T8 and T5 had higher levels of total organic carbon (COT) and the MA system had higher levels of labile carbon (CL) than the other systems, with the exception of TC at a depth of 10-20 cm. In the MA system, COT levels were higher in comparison to use systems TCP, TC and PA while CL levels were higher than the levels observed in use systems TCP and TC. In most cases being analyzed, CL levels were lower than COT levels, therefore this trait can be used as an indicator to assess anthropogenic changes relating to the maintenance or condition of soil organic matter.

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