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

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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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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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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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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Potential soil carbon sequestration of agricultural land around the world

10.5194/egusphere-egu21-3083 ◽

2021 ◽

Author(s):

Sylvia Vetter ◽

Michael Martin ◽

Pete Smith

Keyword(s):

Organic Carbon ◽

Management Practices ◽

Agricultural Land ◽

Ghg Emissions ◽

C Sequestration ◽

Organic Soils ◽

Soil C ◽

Sequestration Potential ◽

The World ◽

Soil C Sequestration

Reducing greenhouse gas (GHG) emissions in to the atmosphere to limit global warming is the big challenge of the coming decades. The focus lies on negative emission technologies to remove GHGs from the atmosphere from different sectors. Agriculture produces around a quarter of all the anthropogenic GHGs globally (including land use change and afforestation). Reducing these net emissions can be achieved through techniques that increase the soil organic carbon (SOC) stocks. These techniques include improved management practices in agriculture and grassland systems, which increase the organic carbon (C) input or reduce soil disturbances. The C sequestration potential differs among soils depending on climate, soil properties and management, with the highest potential for poor soils (SOC stock farthest from saturation).Modelling can be used to estimate the technical potential to sequester C of agricultural land under different mitigation practices for the next decades under different climate scenarios. The ECOSSE model was developed to simulate soil C dynamics and GHG emissions in mineral and organic soils. A spatial version of the model (GlobalECOSSE) was adapted to simulate agricultural soils around the world to calculate the SOC change under changing management and climate.Practices like different tillage management, crop rotations and residue incorporation showed regional differences and the importance of adapting mitigation practices under an increased changing climate. A fast adoption of practices that increase SOC has its own challenges, as the potential to sequester C is high until the soil reached a new C equilibrium. Therefore, the potential to use soil C sequestration to reduce overall GHG emissions is limited. The results showed a high potential to sequester C until 2050 but much lower rates in the second half of the century, highlighting the importance of using soil C sequestration in the coming decades to reach net zero by 2050.

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

10.21203/rs.3.rs-570953/v1 ◽

2021 ◽

Author(s):

Jingwen Chen ◽

Yuanliu Hu ◽

Steven J. Hall ◽

Dafeng Hui ◽

Jianling Li ◽

...

Keyword(s):

Organic Carbon ◽

Soil Organic Carbon ◽

Tropical Forest ◽

Acid Deposition ◽

Southern China ◽

Base Cations ◽

Tropical Soils ◽

C Sequestration ◽

Ph Sensitive ◽

Soil C

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 Carbon Investigation in Three Pedoclimatic and Agronomic Settings of Northern Italy

Sustainability ◽

10.3390/su122410539 ◽

2020 ◽

Vol 12 (24) ◽

pp. 10539

Author(s):

Valentina Brombin ◽

Enrico Mistri ◽

Mauro De Feudis ◽

Camilla Forti ◽

Gian Marco Salani ◽

...

Keyword(s):

Organic Carbon ◽

C Sequestration ◽

Soil Microbial Activity ◽

Soil Disturbance ◽

Northern Italy ◽

Cold Climate ◽

Soil C ◽

Organic Farm ◽

Soil Sustainability ◽

Soil C Sequestration

Sustainable agricultural management is needed to promote carbon (C) sequestration in soil, prevent loss of soil fertility, and reduce the release of greenhouse gases. However, the influence of agronomic practices on soil C sequestration depends on the existing pedoclimatic features. We characterized the soils of three farms far away each other in the Emilia-Romagna region (Northern Italy): an organic farm in the Northern Apennines, a biodynamic farm, and a conventional farm on the Po Plain. The total, inorganic, and organic carbon in soil, as well as the distinct humic fractions were investigated, analyzing both the elemental and isotopic (13C/12C) composition. In soils, organic matter appears to be variously affected by mineralization processes induced by microorganisms that consume organic carbon. In particular, organic carbon declined in farms located in the plain (e.g., organic carbon down to 0.75 wt%; carbon stock0-30 cm down to 33 Mg/ha), because of the warmer climate and moderately alkaline environment that enhance soil microbial activity. On the other hand, at the mountain farm, the minimum soil disturbance, the cold climate, and the neutral conditions favored soil C sequestration (organic carbon up to 4.42 wt%; carbon stock0-30 cm up to 160 Mg/ha) in humified organic compounds with long turnover, which can limit greenhouse gas emissions into the atmosphere. This work shows the need for thorough soil investigations, to propose tailored best-practices that can reconcile productivity and soil sustainability.

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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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A review of sampling designs for the measurement of soil organic carbon in Australian grazing lands

The Rangeland Journal ◽

10.1071/rj09043 ◽

2010 ◽

Vol 32 (2) ◽

pp. 227 ◽

Cited By ~ 66

Author(s):

D. E. Allen ◽

M. J. Pringle ◽

K. L. Page ◽

R. C. Dalal

Keyword(s):

Microbial Biomass ◽

Organic Carbon ◽

Soil Organic Carbon ◽

Plant Growth ◽

Temporal Change ◽

Organic C ◽

Soil C ◽

Efficient Sampling ◽

Soc Stock ◽

Grazing Lands

The accurate measurement of the soil organic carbon (SOC) stock in Australian grazing lands is important due to the major role that SOC plays in soil productivity and the potential influence of soil C cycling on Australia’s greenhouse gas emissions. However, the current sampling methodologies for SOC stock are varied and potentially conflicting. It was the objective of this paper to review the nature of, and reasons for, SOC variability; the sampling methodologies commonly used; and to identify knowledge gaps for SOC measurement in grazing lands. Soil C consists of a range of biological materials, in various SOC pools such as dissolved organic C, micro- and meso-fauna (microbial biomass), fungal hyphae and fresh plant residues in or on the soil (particulate organic C, light-fraction C), the products of decomposition (humus, slow pool C) and complexed organic C, and char and phytoliths (inert, passive or resistant C); and soil inorganic C (carbonates and bicarbonates). Microbial biomass and particulate or light-fraction organic C are most sensitive to management or land-use change; resistant organic C and soil carbonates are least sensitive. The SOC present at any location is influenced by a series of complex interactions between plant growth, climate, soil type or parent material, topography and site management. Because of this, SOC stock and SOC pools are highly variable on both spatial and temporal scales. This creates a challenge for efficient sampling. Sampling methods are predominantly based on design-based (classical) statistical techniques, crucial to which is a randomised sampling pattern that negates bias. Alternatively a model-based (geostatistical) analysis can be used, which does not require randomisation. Each approach is equally valid to characterise SOC in the rangelands. However, given that SOC reporting in the rangelands will almost certainly rely on average values for some aggregated scale (such as a paddock or property), we contend that the design-based approach might be preferred. We also challenge soil surveyors and their sponsors to realise that: (i) paired sites are the most efficient way of detecting a temporal change in SOC stock, but destructive sampling and cumulative measurement errors decrease our ability to detect change; (ii) due to (i), an efficient sampling scheme to estimate baseline status is not likely to be an efficient sampling scheme to estimate temporal change; (iii) samples should be collected as widely as possible within the area of interest; (iv) replicate of laboratory analyses is a critical step in being able to characterise temporal change. Sampling requirements for SOC stock in Australian grazing lands are yet to be explicitly quantified and an examination of a range of these ecosystems is required in order to assess the sampling densities and techniques necessary to detect specified changes in SOC stock and SOC pools. An examination of techniques that can help reduce sampling requirements (such as measurement of the SOC fractions that are most sensitive to management changes and/or measurement at specific times of the year – preferably before rapid plant growth – to decrease temporal variability), and new technologies for in situ SOC measurement is also required.

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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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