Increased Iron-Carbon Interactions Under Long-Term Acid Deposition Enhance Soil Organic Carbon Sequestration in A Tropical Forest in Southern China

Abstract Atmospheric acid deposition remains a widespread problem that may influence the protection of carbon (C) in soil by altering organo-mineral interactions. However, the impacts of additional acidity on organo-mineral interactions and soil C sequestration in naturally acidic tropical soils with a high content of reactive iron (Fe) phases have not been well studied. Here we sampled a nearly 10-yr field experiment with a gradient of acidity treatments (0, 9.6, 32, 96 mol H+ ha− 1 yr− 1 as nitric acid + sulfuric acid) to examine how acidification alters organo-mineral interactions and soil organic carbon (SOC) pools in a tropical forest in southern China. As expected, soil acidification significantly enhanced the leaching of base cations (e.g., Ca2+), and it also altered the solubility and composition of Fe and Al phases. The acidity treatments converted more crystalline Fe (oxyhydr)oxides to short-range-ordered phases, resulting in a large increase in Fe-bound C vs. a relatively small decrease in Ca-bound C. Overall, the acidity treatments increased the mineral-associated C stock to 32.5–36.4 Mg C ha− 1 vs. 28.8 Mg C ha− 1 in the control, accounting for 71–83% of the observed increase in total SOC stock. These findings highlight the importance of pH-sensitive geochemical changes and the key roles of Fe in regulating the response of SOC to further inputs of acid deposition even in highly weathered and naturally acidic soils. The magnitude of SOC changes observed here indicates the importance of including pH-sensitive geochemistry in Earth system models to predict ecosystem C budgets under future acid deposition scenarios.

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Soil organic carbon dynamics and sequestration potential in cropland-grassland agro-ecosystems

10.5194/egusphere-egu21-12465 ◽

2021 ◽

Author(s):

Thomas Guillaume ◽

David Makowski ◽

Zamir Libohova ◽

Luca Bragazza ◽

Sokrat Sinaj

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Management Practices ◽

Storage Capacity ◽

Agricultural Soils ◽

C Sequestration ◽

Boundary Line ◽

Monitoring Networks ◽

Soil C ◽

Sequestration Potential

Increasing soil organic carbon (SOC) in agro-ecosystems enables to address simultaneously food security as well as climate change adaptation and mitigation. Croplands represent a great potential to sequester atmospheric C because they are depleted in SOC. Hence, reliable estimations of SOC deficits in agro-ecosystems are crucial to evaluate the C sequestration potential of agricultural soils and support management practices. Using a 30-year old soil monitoring networks with 250 sites established in western Switzerland, we identified factors driving the long-term SOC dynamics in croplands (CR) and permanent grasslands (PG) and quantified SOC deficit. A new relationship between the silt + clay (SC) soil particles and the C stored in the mineral-associated fraction (MAOMC) was established. We also tested the assumption about whether or not PG can be used as carbon-saturated reference sites. The C-deficit in CR constituted about a third of their potential SOC content and was mainly affected by the proportion of temporary grassland in the crop rotation. SOC accrual or loss were the highest in sites that experienced land-use change. The MAOMC level in PG depended on the C accrual history, indicating that C-saturation level was not coincidental. Accordingly, the relationship between MAOMC and SC to determine soil C-saturation should be estimated by boundary line analysis instead of least squares regressions. In conclusion, PG do provide an additional SOC storage capacity under optimal management, though the storage capacity is greater for CR.

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Modeling soil organic carbon dynamics and their driving factors in the main global cereal cropping systems

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-11849-2017 ◽

2017 ◽

Vol 17 (19) ◽

pp. 11849-11859 ◽

Cited By ~ 7

Author(s):

Guocheng Wang ◽

Wen Zhang ◽

Wenjuan Sun ◽

Tingting Li ◽

Pengfei Han

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Crop Residue ◽

Retention Rate ◽

C Sequestration ◽

Soil C ◽

C Input ◽

Soil C Sequestration ◽

Residue Retention

Abstract. Changes in the soil organic carbon (SOC) stock are determined by the balance between the carbon input from organic materials and the output from the decomposition of soil C. The fate of SOC in cropland soils plays a significant role in both sustainable agricultural production and climate change mitigation. The spatiotemporal changes of soil organic carbon in croplands in response to different carbon (C) input management and environmental conditions across the main global cereal systems were studied using a modeling approach. We also identified the key variables that drive SOC changes at a high spatial resolution (0.1°  ×  0.1°) and over a long timescale (54 years from 1961 to 2014). A widely used soil C turnover model (RothC) and state-of-the-art databases of soil and climate variables were used in the present study. The model simulations suggested that, on a global average, the cropland SOC density increased at annual rates of 0.22, 0.45 and 0.69 Mg C ha−1 yr−1 under crop residue retention rates of 30, 60 and 90 %, respectively. Increasing the quantity of C input could enhance soil C sequestration or reduce the rate of soil C loss, depending largely on the local soil and climate conditions. Spatially, under a specific crop residue retention rate, relatively higher soil C sinks were found across the central parts of the USA, western Europe, and the northern regions of China. Relatively smaller soil C sinks occurred in the high-latitude regions of both the Northern and Southern hemispheres, and SOC decreased across the equatorial zones of Asia, Africa and America. We found that SOC change was significantly influenced by the crop residue retention rate (linearly positive) and the edaphic variable of initial SOC content (linearly negative). Temperature had weak negative effects, and precipitation had significantly negative impacts on SOC changes. The results can help guide carbon input management practices to effectively mitigate climate change through soil C sequestration in croplands on a global scale.

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Modeling soil organic carbon dynamics and its driving factors in global main cereal cropping systems

10.5194/acp-2017-430 ◽

2017 ◽

Author(s):

Guocheng Wang ◽

Wen Zhang ◽

Wenjuan Sun ◽

Tingting Li ◽

Pengfei Han

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Crop Residue ◽

Retention Rate ◽

C Sequestration ◽

The United States ◽

Soil C ◽

C Input ◽

Soil C Sequestration ◽

Residue Retention

Abstract. The net fluxes of carbon dioxide (CO2) between the atmosphere and agricultural systems are mainly characterized by the changes in soil carbon stock, which is determined by the balance between carbon input from organic materials and output through soil C decomposition. The spatiotemporal changes of cropland soil organic carbon (SOC) in response to different carbon (C) input management and environmental conditions across the global main cereal systems were studied using a modeling approach. We also identified the key variables driving SOC changes at a high spatial resolution (0.1° × 0.1°) and long time scale (54 years from 1961 to 2014). The widely used soil C turnover model (RothC) and the state-of-the-art databases of soil and climate were used in the present study. The model simulations suggested that, on a global average, the cropland SOC density increased at an annual rate of 0.22, 0.45 and 0.69 MgC ha−1 yr−1 under a crop residue retention rate of 30 %, 60 % and 90 %, respectively. Increased quantity of C input could enhance the soil C sequestration or reduce the soil C loss rate, depending largely on the local soil and climate conditions. Spatially, under a certain crop residue retention rate, a relatively higher soil C sink were generally found across the central parts of the United States, western Europe, northern regions of China, while a relatively smaller soil C sink generally occurred in regions at high latitudes of both northern and southern hemisphere, and SOC decreased across the equatorial zones of Asia, Africa and America. We found that SOC change was significantly influenced by the crop residue retention rate (linearly positive), and the edaphic variable of initial SOC content (linearly negative). Temperature had weakly negative effects, and precipitation had significantly negative impacts on SOC changes. The results can help target carbon input management for effectively mitigating climate change through cropland soil C sequestration on a global scale.

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Stability and storage of soil organic carbon in a heavy-textured Karst soil from south-eastern Australia

Soil Research ◽

10.1071/sr13296 ◽

2014 ◽

Vol 52 (5) ◽

pp. 476 ◽

Cited By ~ 13

Author(s):

Eleanor Hobley ◽

Garry R. Willgoose ◽

Silvia Frisia ◽

Geraldine Jacobsen

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Profile ◽

C Sequestration ◽

Mineral Association ◽

Radiocarbon Dates ◽

Organic C ◽

Soil C ◽

Eastern Australia ◽

Particle Size Fractionation

Both aggregation and mineral association have been previously found to enhance soil organic carbon (SOC) storage (the amount of organic C retained in a soil), and stability (the length of time organic C is retained in a soil). These mechanisms are therefore attractive targets for soil C sequestration. In this study, we investigate and compare SOC storage and stability of SOC associated with fine minerals and stored within aggregates using a combination of particle-size fractionation, elemental analysis and radiocarbon dating. In this heavy-textured, highly aggregated soil, SOC was found to be preferentially associated with fine minerals throughout the soil profile. By contrast, the oldest SOC was located in the coarsest, most highly aggregated fraction. In the topsoil, radiocarbon ages of the aggregate-associated SOC indicate retention times in the order of centuries. Below the topsoil, retention times of aggregate-SOC are in the order of millennia. Throughout the soil profile, radiocarbon dates indicate an enhanced stability in the order of centuries compared with the fine mineral fraction. Despite this, the radiocarbon ages of the mineral-associated SOC were in the order of centuries to millennia in the subsoil (30–100 cm), indicating that mineral-association is also an effective stabilisation mechanism in this subsoil. Our results indicate that enhanced SOC storage does not equate to enhanced SOC stability, which is an important consideration for sequestration schemes targeting both the amount and longevity of soil carbon.

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Soil organic carbon stocks under different land uses in Chure region of Makawanpur district, Nepal

SAARC Journal of Agriculture ◽

10.3329/sja.v16i2.40255 ◽

2019 ◽

Vol 16 (2) ◽

pp. 13-23 ◽

Cited By ~ 2

Author(s):

P Ghimire ◽

B Bhatta ◽

B Pokhrel ◽

G Kafle ◽

P Paudel

Keyword(s):

Land Use ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Management Practices ◽

C Sequestration ◽

Organic Carbon Content ◽

Degraded Forest ◽

Degraded Land ◽

Soil C ◽

Soc Stock

Soil C sequestration through enhanced land use is a good strategy to mitigate the increasing concentration of atmospheric CO2. A study was conducted in Chhatiwan VDC of Makawanpur District to compare soil organic carbon (SOC) stocks of four main land use types such as forest, degraded forest, Khet and Bari land. Stratified random sampling method was used for collecting soil samples. Organic carbon content was determined by Walkley and Black method. Total SOC stock of different types of land followed the order: as Forest (110.0 t ha-1) > Bari (96.5 t ha-1) > Khet (86.8 t ha-1) > Degraded land (72.0 t ha-1). The SOC% declined with soil depths. The SOC% at 0–20 cm depth was highest (1.26 %) that recorded in the forest soils and lowest (0.37%) at 80- 100cm depth in degraded forest land. Thus, the SOC stock varied with land use systems and soil depths. The study suggests a need for appropriate land use strategy and sustainable soil management practices to improve SOC stock. SAARC J. Agri., 16(2): 13-23 (2018)

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Short-Term Effect of Sugarcane Straw on Soil Organic Carbon Pools

Journal of Agricultural Science ◽

10.5539/jas.v10n8p405 ◽

2018 ◽

Vol 10 (8) ◽

pp. 405 ◽

Cited By ~ 2

Author(s):

Luiz Fernando C. Leite ◽

Edvaldo Sagrilo ◽

Ademir Sergio F. de Araújo ◽

Henrique Antunes de Souza

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Soil Surface ◽

Tropical Soils ◽

C Sequestration ◽

Term Effect ◽

Short Term ◽

Short Term Effect ◽

Sugarcane Straw ◽

Soc Stocks

This study aimed to evaluate the short-term effect of sugarcane straw on soil organic carbon (SOC) stocks in tropical soils. The treatments simulated the maintenance of different rates of sugarcane straw (0, 2.2, 5.1, 7.8 and 12 t ha-1) applied on the soil surface, with four replication, and evaluated chemical and biological attributes in four depths (0-0.05; 0.05-0.10; 0.10-0.20; 0.20-0.40 m). Results from soil samples collected in the rainy and dry seasons showed evidence of positive short-term effects of green harvest either on labile and humified soil organic matter (SOM) pools. For the total SOC stocks, we observed linear responses with straw rates in both sampling seasons. A decreased humification index in the topsoil suggests more labile C pools available in the soil, resulting in a significant increase in microbial activity. Microbial indicators point towards a steady equilibrium in SOC turnover, which can lead to future lower increases in SOC stocks if high straw amounts are maintained on the soil surface. Therefore, long-term studies under low-latitude areas are necessary to model the potential of C sequestration in sugarcane green harvest systems.

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High organic carbon input can accelerate global warming in rice paddy soil: increase unprotected soil organic carbon and CH4 emission

10.5194/egusphere-egu21-9438 ◽

2021 ◽

Author(s):

Hyeonji Song ◽

Snowie Galgo ◽

Ronley Canatoy ◽

Hogyeong Chae ◽

Pil Joo Kim

Keyword(s):

Global Warming ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Rice Paddy ◽

C Sequestration ◽

Soil C ◽

Saturation Degree ◽

Soil Saturation ◽

Soc Stock ◽

Soil C Sequestration

Soil C sequestration is widely regarded as the most reasonable way to mitigate global warming. Traditionally, a high amount of organic carbon (OC) input is strongly recommended to increase soil organic carbon (SOC) stocks in croplands. However, according to the whole-soil saturation theory, stable SOC (mineral-associated SOC) accumulation can be limited at a certain point, relying on silt and clay contents. Most studies based on the theory were conducted in aerobic soil condition. This relationship is still uncertain in a rice paddy that makes up 10.8% of total arable land and has an anaerobic soil environment. In this study, we investigated high OC addition can enhance soil C sequestration in a rice paddy. We added different OC levels (0.5, 2.0, 2.9, and 4.6 Mg C ha-1 yr-1) in rice paddy by incorporating cover crop biomass for nine years. SOC stock and soil saturation degree were determined. Unprotected, sand-associated, silt-associated, and clay-associated SOC were separated via density and size fractionation. Respired C losses (CO2-C and CH4-C) were monitored using the static closed chamber method. SOC stock did not linearly increase with higher amount of OC input. The carbon sequestration efficiency (i.e. the increase of SOC per unit of OC input) decreases with the amount OC added. Higher OM input significantly increased unprotected labile SOC content. Unprotected SOC (<1.85 g cm-3) exponentially increased as the SOC saturation degree was higher. On the other hand, stable SOC content did not exhibit a linear relationship with the SOC saturation degree. The higher OC addition level exponentially increased respired C loss. In particular, C loss via CH4 was more sensitive to high OC addition. We conclude that higher OC addition in rice paddy without consideration in terms of SOC stock saturation point can accelerate global warming by increasing labile SOC accumulation and CH4 emission.

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Impact of pasture establishment on CO2 emissions from a Vertisol: Consequences for soil C sequestration (Martinique, West Indies)

Canadian Journal of Soil Science ◽

10.4141/s05-022 ◽

2006 ◽

Vol 86 (5) ◽

pp. 779-782 ◽

Cited By ~ 3

Author(s):

T. Chevallier ◽

E. Blanchart ◽

A. Albrecht ◽

C. Feller ◽

M. Bernoux

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

West Indies ◽

C Sequestration ◽

Soil C ◽

C Storage ◽

Digitaria Decumbens ◽

Market Gardening ◽

Soil C Sequestration ◽

Soc Mineralization

Establishing pasture on cultivated tropical Vertisols can increase soil organic carbon (SOC), but it is not known whether this increase results solely from enhanced inputs or also from suppressed mineralization. We measured CO2 emissions from a Vertisol under market gardening, and under “young” and “old” Digitaria decumbens pastures. Emissions of CO2-C increased in pastures, compared to market gardening, but relative SOC mineralization (CO2-C/SOC) decreased, implying the protection of SOC against mineralization with pasture establishment. Key words: Tropical pasture, carbon fluxes, soil organic carbon, physical protection, C storage

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Soil organic carbon stocks in tropical soil systems under rainforests controlled by geochemistry

10.5194/egusphere-egu2020-12993 ◽

2020 ◽

Author(s):

Mario Reichenbach ◽

Peter Fiener ◽

Florian Wilken ◽

Johan Six ◽

Laurent Kidinda ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Tropical Forest ◽

Carbon Stocks ◽

Parent Material ◽

Temperate Climate ◽

Soil C ◽

Geochemical Properties ◽

The Relationship ◽

Soc Stocks

Soil mineralogy plays an important role in stabilizing soil organic carbon (SOC) against decomposition by forming organo-mineral complexes with reactive mineral surfaces. However, few studies take the influence of parent material geochemistry on the development of C stabilization mechanisms into account. In addition, studies evaluating C stabilization in soil are often limited to temperate climate zones with young to intermediate aged soils. This is not representative for older, deeply weathered and leached tropical systems and limits our understanding of the relationship between geology, soil formation and their effect on C stabilization.Here, we study the relationship between soil carbon stabilization and the geochemical properties of soils developed on different parent material along geomorphic transects in pristine tropical forest systems under comparable climate. Our study is located in the eastern part of the Congo basin along the East African Rift Mountain System where we sampled 36 one meter soil cores along nine geomorphic transects on geologies ranging from mafic to felsic geochemistry.Carbon stocks ranged between 2.67 tC ha-1 to 85.75 tC ha-1 and were on average composed of 4.5% (&#177;5.3% SD) coarse particulate organic matter, 46.0% (&#177;10.3% SD) (micro)aggregates associated C and 49.6% (&#177;11.2% SD) free silt and clay associated C. Our analysis shows that the topographic position of the investigated soils had no effect on SOC stocks and the distribution of soil C fractions. Regression models and partial correlation analysis reveal that strong correlations of SOC stocks exists to geochemical properties of the solid phase of soil but not to the distribution of soil C fractions. SOC decreased strongly with soil depth on soils developed on felsic parent material, but less so on mafic or intermediate parent material. In addition, mafic geochemistry shows significantly higher SOC stocks compared to their felsic counterparts.We conclude that despite long-lasting weathering, the contrasting geochemistry of the underlying parent material leaves a footprint in soil geochemistry that affects C stocks but less so on stabilization mechanisms. We hypothesis that carbon dynamics in these undisturbed tropical forest systems are more driven by C input and nutrient recycling than by variation in C stabilization potential.&#160;&#160;

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