Soil carbon market-based instrument pilot – the sequestration of soil organic carbon for the purpose of obtaining carbon credits

Soil Research ◽  
2021 ◽  
Vol 59 (1) ◽  
pp. 12 ◽  
Author(s):  
Warwick Badgery ◽  
Brian Murphy ◽  
Annette Cowie ◽  
Susan Orgill ◽  
Andrew Rawson ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Organic Amendments ◽  
C Sequestration ◽  
Total Carbon ◽  
Emissions Reduction ◽  
Reduced Tillage ◽  
Permanent Pasture ◽  
Soc Stocks

Increasing soil organic carbon (SOC) in Australian farming systems has the potential to offset greenhouse gas emissions. Even though methods for soil carbon (C) sequestration have been developed under the Australian Government’s Emissions Reduction Fund, the scope for farm-scale soil C sequestration is poorly understood. A pilot scheme was developed in Central West New South Wales to trial the use of a market-based instrument to encourage farmers to change farm management to increase SOC. This paper reports changes to SOC stocks measured on farms that were successfully contracted in the pilot. The 10 contracted farms were those that submitted the lowest bid per Mg CO2-e. Four land uses were contracted in the pilot: (1) reduced tillage cropping (reference); (2) reduced tillage cropping with organic amendments (e.g. biosolids or compost); (3) conversion from cropping land to permanent pasture; and (4) conversion from cropping land to permanent pasture with organic amendments. At each site a minimum of 10 locations (sampling points) were sampled and analysed for total carbon (LECO elemental analyser) and bulk density calculated. The SOC stocks (0–0.3 m) were assessed before (2012) and after the pilot (2017; calculated on equivalent soil mass of 2012), with 60% of sites showing a significant increase. Pasture had a higher rate of SOC sequestration than reduced tillage cropping (1.2 vs 0.28 Mg C ha–1 year–1, 0–0.3 m); and organic amendments had higher rates of SOC sequestration than without (1.14 vs 0.78 Mg C ha–1 year–1, 0–0.3 m). The results of the pilot demonstrated increases in SOC, using quantification methods consistent with the current Measurement Method of the Australian Government’s Emissions Reduction Fund policy used to generate Australian Carbon Credit Units. The results require careful interpretation as rates of sequestration are likely to be lower in the longer term than initial rates of change seen in this pilot (five years), and the pilot intentionally selected sites with initially low SOC, which ensured a greater opportunity to sequester SOC.

scholarly journals The use of radiocarbon <sup>14</sup>C to constrain carbon dynamics in the soil module of the land surface model ORCHIDEE (SVN r5165)

2018 ◽  
Author(s):  
Marwa Tifafi ◽  
Marta Camino-Serrano ◽  
Christine Hatté ◽  
Hector Morras ◽  
Lucas Moretti ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Land Surface ◽  
Carbon Stock ◽  
Land Surface Model ◽  
Carbon Dynamics ◽  
Total Carbon ◽  
Soil Parameters ◽  
Surface Model

Abstract. Despite the importance of soil as a large component of the terrestrial ecosystems, the soil compartments are not well represented in the Land Surface Models (LSMs). Indeed, soils in current LSMs are generally represented based on a very simplified schema that can induce a misrepresentation of the deep dynamics of soil carbon. Here, we present a new version of the IPSL-Land Surface Model called ORCHIDEE-SOM, incorporating the 14C dynamic in the soil. ORCHIDEE-SOM, first, simulates soil carbon dynamics for different layers, down to 2 m depth. Second, concentration of dissolved organic carbon (DOC) and its transport are modeled. Finally, soil organic carbon (SOC) decomposition is considered taking into account the priming effect. After implementing the 14C in the soil module of the model, we evaluated model outputs against observations of soil organic carbon and 14C activity (F14C) for different sites with different characteristics. The model managed to reproduce the soil organic carbon stocks and the F14C along the vertical profiles. However, an overestimation of the total carbon stock was noted, but was mostly marked on the surface. Then, thanks to the introduction of 14C, it has been possible to highlight an underestimation of the age of carbon in the soil. Thereafter, two different tests on this new version have been established. The first was to increase carbon residence time of the passive pool and decrease the flux from the slow pool to the passive pool. The second was to establish an equation of diffusion, initially constant throughout the profile, making it vary exponentially as a function of depth. The first modifications did not improve the capacity of the model to reproduce observations whereas the second test showed a decrease of the soil carbon stock overestimation, especially at the surface and an improvement of the estimates of the carbon age. This assumes that we should focus more on vertical variation of soil parameters as a function of depth, mainly for diffusion, in order to upgrade the representation of global carbon cycle in LSMs, thereby helping to improve predictions of the future response of soil organic carbon to global warming.

Carbon storage in cotton soils of northern New South Wales

Soil Research ◽  
2003 ◽  
Vol 41 (5) ◽  
pp. 889 ◽  
Author(s):  
T. A. Knowles ◽  
B. Singh
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Carbon Content ◽  
Soil Carbon ◽  
Inorganic Carbon ◽  
Carbon Pool ◽  
Total Carbon ◽  
Soil Types ◽  
Soil Carbon Pool ◽  
Total Soil

Soil carbon is an important component of the global carbon cycle with an estimated pool of soil organic carbon of about 1500 Gt. There are few estimates of the pool of inorganic carbon, but it is thought to be approximately 50% of the organic carbon pool. There is no detailed study on the estimation of the soil carbon pool for Australian soils.In order to quantify the carbon pools and to determine the extent of spatial variability in the organic and inorganic carbon pools, 120 soil cores were taken down to a depth of 0.90 m from a typical cotton field in northern NSW. Three cores were also taken from nearby virgin bushland and these samples were used as paired samples. Each soil core was separated into 4 samples, i.e. 0–0.15, 0.15–0.30, 0.30–0.60, and 0.60–0.90 m. Soil organic carbon was determined by wet oxidation and inorganic carbon content was determined using the difference between total carbon and organic carbon, and confirmed by the acid dissolution method. Total carbon was measured using a LECO CHN analyser. Soil organic carbon of the field constituted 62% (0–0.15 m), 58% (0.15–0.30 m), 60% (0.30–0.60 m), and 67% (0.60–0.90 m) of the total soil carbon. The proportion of inorganic carbon in total carbon is higher than the global average of 32%. Organic carbon content was relatively higher in the deeper layers (>0.30�m) of the studied soils (Vertosols) compared with other soil types of Australia. The carbon content varied across the field, however, there was little correlation between the soil types (grey, red, or intergrade colour) and carbon content. The total soil carbon pool of the studied field was estimated to be about 78 t/ha for 0–0.90 m layer, which was approximately 58% of the total soil carbon in the soil under nearby remnant bushland (136 t/ha). The total pool of carbon in the cotton soils of NSW was estimated to be 44.8 Mt C, where organic carbon and inorganic carbon constitute 34.9 Mt C and 9.9 Mt C, respectively. Based on the results of a limited number of paired sites under remnant vegetation, it was estimated that about 18.9 Mt of C has been lost from Vertosols by cotton cropping in NSW. With more sustainable management practices such as conservation tillage and green manuring, some of the lost carbon can be resequestered, which will help to mitigate the greenhouse effect, improve soil quality and may increase crop yield.

Simulation of soil organic carbon stock and greenhouse gases emission from Perennial Energy Crops cultivation cycle in Italy with ECOSSE model: from establishment to removal

2020 ◽  
Author(s):  
Enrico Martani ◽  
Marcello Pilla ◽  
Andrea Ferrarini ◽  
Stefano Amaducci ◽  
Astley Hastings
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Greenhouse Gases ◽  
Soil Carbon ◽  
Arable Land ◽  
Belowground Biomass ◽  
Energy Crops ◽  
Total Carbon ◽  
Soc Stock ◽  
Perennial Energy Crops

&lt;p&gt;Soil organic carbon (SOC) is an important carbon pool sensitive to land use change (LUC). There are concerns that at the end of PECs cultivation cycle, the re-conversion of these crops back to arable land could negatively impact the SOC stock. However, a positive effect of reconversion on SOC is possible, due to the high amount of C added to the soil with the disruption of belowground biomass (BGB) during re-conversion process. In this study, C storage potential in SOC and BGB of six perennial energy crops (PECs) was measured in a 11 years old field trial in Italy before its reconversion to arable land. SOC dynamics and greenhouse gases (GHGs) emission were measured in the first two years after the reconversion. SOC and GHG measurements were compared to ECOSSE soil carbon model predictions (run for a LUC from arable land to PECs and re-conversion to arable land) to understand SOC dynamics. After 11 years of cultivation, PECs significantly increased SOC stock respect to arable land. In average, BGB accounted for the 68% of total carbon stocked by PECs. The ECOSSE soil carbon model successfully simulated the dynamics of SOC pool and the GHGs emissions from soil after the re-conversion of PECs.&lt;/p&gt;

scholarly journals Global distribution of soil organic carbon – Part 1: Masses and frequency distributions of SOC stocks for the tropics, permafrost regions, wetlands, and the world

SOIL ◽  
2015 ◽  
Vol 1 (1) ◽  
pp. 351-365 ◽  
Author(s):  
M. Köchy ◽  
R. Hiederer ◽  
A. Freibauer
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Bulk Density ◽  
Tropical Soils ◽  
Frequency Distributions ◽  
Tropical Regions ◽  
The World ◽  
Global Soil ◽  
Soc Stocks

Abstract. The global soil organic carbon (SOC) mass is relevant for the carbon cycle budget and thus atmospheric carbon concentrations. We review current estimates of SOC stocks and mass (stock × area) in wetlands, permafrost and tropical regions and the world in the upper 1 m of soil. The Harmonized World Soil Database (HWSD) v.1.2 provides one of the most recent and coherent global data sets of SOC, giving a total mass of 2476 Pg when using the original values for bulk density. Adjusting the HWSD's bulk density (BD) of soil high in organic carbon results in a mass of 1230 Pg, and additionally setting the BD of Histosols to 0.1 g cm−3 (typical of peat soils), results in a mass of 1062 Pg. The uncertainty in BD of Histosols alone introduces a range of −56 to +180 Pg C into the estimate of global SOC mass in the top 1 m, larger than estimates of global soil respiration. We report the spatial distribution of SOC stocks per 0.5 arcminutes; the areal masses of SOC; and the quantiles of SOC stocks by continents, wetland types, and permafrost types. Depending on the definition of "wetland", wetland soils contain between 82 and 158 Pg SOC. With more detailed estimates for permafrost from the Northern Circumpolar Soil Carbon Database (496 Pg SOC) and tropical peatland carbon incorporated, global soils contain 1325 Pg SOC in the upper 1 m, including 421 Pg in tropical soils, whereof 40 Pg occurs in tropical wetlands. Global SOC amounts to just under 3000 Pg when estimates for deeper soil layers are included. Variability in estimates is due to variation in definitions of soil units, differences in soil property databases, scarcity of information about soil carbon at depths > 1 m in peatlands, and variation in definitions of "peatland".

Short-term responses of soil organic carbon and its labile fractions to different manure Nitrogen input in a double-cropping rice field

2020 ◽  
Vol 158 (1-2) ◽  
pp. 119-127
Author(s):  
Haiming Tang ◽  
Xiaoping Xiao ◽  
Chao Li ◽  
Xiaochen Pan ◽  
Kaikai Cheng ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Southern China ◽  
Organic Manure ◽  
Chemical Fertilizer ◽  
Organic C ◽  
Double Cropping ◽  
Labile C ◽  
Soc Stocks

AbstractChanges in soil bulk density (BD), soil organic carbon (SOC) content, SOC stocks and soil labile organic C fractions (mineralizable C (Cmin), microbial biomass C (MBC), dissolved organic C (DOC), particulate organic C (POC), light fraction organic C (LFOC) and permanganate oxidizable C (KMnO4-C)) were explored over 3 years in a double-cropping rice system of southern China. Five organic and inorganic nitrogen (N) inputs were used: (1) 100% from chemical fertilizer (M0), (2) 30% from organic manure, 70% from chemical fertilizer (M30), (3) 50% from organic manure, 50% from chemical fertilizer (M50), (4) 100% from organic manure (M100) and (5) without N fertilizer input, as control (CK). All organic manure treatments decreased BD significantly in the 0–20 cm soil layer compared with CK. The SOC content and stocks with organic manure were significantly higher than in M0 or CK; also, the cumulative amount of SOC stocks in M30 and M50 increased at the plough layer, compared with CK. The non-labile C content increased significantly and the percentage of labile C were significantly higher with organic manure application than in M0 or CK. The soil carbon management index (CMI) also increased significantly under the application of organic manure. Therefore, application of organic manure can increase the pool of stable C in surface layers, and increase content and percentage of labile C. Based on soil carbon storage and CMI, the combined application of 30 or 50% N of organic manure with chemical fertilizer improves carbon cycling services and soil quality in southern China paddy soil.

Relative Contribution of aggregated soil Carbon to soil organic carbon pool in an Ultisol, SouthEastern Nigeria

2020 ◽  
Author(s):  
Akudo Ogechukwu Onunwa ◽  
Ifeyinwa Monica Uzoh ◽  
Chukwuebuka Christopher Okolo ◽  
Charles Arinze Igwe ◽  
John Nwite
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Organic Amendments ◽  
Aggregate Size ◽  
Cropping System ◽  
Carbon Pool ◽  
Relative Contribution ◽  
Split Plot ◽  
Organic Carbon Pool

&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160;&amp;#160; &lt;strong&gt;ABSTRACT&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Maintenance of Soil Organic Matter (SOM) has been recognized as a strategy that could reduce soil degradation, improve soil organic carbon (SOC) pool thereby reducing atmospheric concentration of carbon iv oxide (CO&lt;sub&gt;2&lt;/sub&gt;) so as to ameliorate the effect of carbon and other greenhouse gases on the environment. Soil fertility depletion in the humid tropics is a serious problem emanating from erosion and leaching due to intense rainfall. Decrease in soil fertility and productivity is believed to be due to depletion in SOM. This study aims at determining the relative contributions (RC) of the various aggregated soil carbon (C&lt;sub&gt;WSA&lt;/sub&gt;) (which is a function of available organic matter in the soil) to Soil organic carbon pool. Soil samples were collected from an area of land (0.1125ha) planted to sole cowpea, sole maize and maize-cowpea intercrop in No till (NT) and conventionally tilled (CT) plots amended with poultry droppings (PD), pig waste (PW), cassava peels (CP) at 20t/ha each and a control in a split-split plot in Randomized Complete Block Design with three replicates. Cropping system was assigned to the main plots, tillage system was assigned to split plot while organic amendments and control was assigned to the split-split plot measuring 7.5m&lt;sup&gt;2&lt;/sup&gt;. The same treatment was maintained for two planting seasons (2012 and 2013), with the residual taken in 2013. Soil samples were collected at 0-30cm at the end of each planting season and SOC of the whole soil and the aggregated&amp;#160; soil carbon (2mm, 2-1mm,1-0.5mm 0.5-0.25mm and &lt; 0.25mm) were determined using Walkley&amp;#160; and Black method as described by Nelson and Sommers (1982). Data collected were subjected to Analysis of Variance (ANOVA) using Genstat release 7.22D. The result revealed that there is a trend of aggregate size fractions 1-0.25mm contributing more carbon to the SOC than aggregate size fractions &gt;2-1mm irrespective of the cropping system, tillage method or organic amendments applied. The highest relative contribution of aggregated soil carbon to the SOC pool shifted from the micro-aggregates (&lt;0.25mm) to the macro-aggregates (1.0-0.25mm) for as long as the organic amendments lasted but gradually returned to the micro-aggregates when the amendments were withdrawn. It is therefore recommended that organic amendments be use to improve the soil aggregation which goes a long way in improving soil carbon pool thereby ameliorating the effect of carbon and other green house gases on the environment.&lt;/p&gt;&lt;p&gt;Key Words: Soil Organic carbon pool, Soil Aggregated carbon, Relative Contribution, Macro and Micro Aggregates&lt;/p&gt;

scholarly journals ORCHIDEE-SOM: modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe

2018 ◽  
Vol 11 (3) ◽  
pp. 937-957 ◽  
Author(s):  
Marta Camino-Serrano ◽  
Bertrand Guenet ◽  
Sebastiaan Luyssaert ◽  
Philippe Ciais ◽  
Vladislav Bastrikov ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Carbon ◽  
Land Surface ◽  
Coniferous Forest ◽  
Soil Horizon ◽  
Surface Model ◽  
Model Parameters ◽  
Soc Stocks

Abstract. Current land surface models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, and thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. This common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to 2 m. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on and desorption from soil minerals, diffusion of SOC and DOC, and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: a coniferous forest, a deciduous forest, a grassland, and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- and depth-dependent parameterization of the new input model parameters, such as the turnover times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global warming.

scholarly journals Spartina alterniflora Leaf and Soil Eco-Stoichiometry in the Yancheng Coastal Wetland

Plants ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 13
Author(s):  
Xueyan Zuo ◽  
Lijuan Cui ◽  
Wei Li ◽  
Yinru Lei ◽  
Zhiguo Dou ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Soil Carbon ◽  
Spartina Alterniflora ◽  
Soil Salinity ◽  
Coastal Wetland ◽  
Coordination Mechanism ◽  
Total Carbon ◽  
Nitrogen And Phosphorus ◽  
Nitrogen Phosphorus

Carbon, nitrogen, and phosphorus—nutrient and restrictive elements for plant growth and important components of the plant body—are mainly transferred and exchanged between plants and the soil environment. Changes in the carbon, nitrogen, and phosphorus eco-stoichiometry greatly impact the growth and expansion of Spartina alterniflora, and understanding these changes can reveal the nutrient coordination mechanism among ecosystem components. To explore the relationship between leaf and soil eco-stoichiometry and determine the key soil factors that affect leaf eco-stoichiometry, we collected leaf and soil samples of S. alterniflora at different tidal levels (i.e., 1, 3, and 5 km away from the coastline) in a coastal wetland in the Yancheng Elk Nature Reserve, Jiangsu province. We measured the leaf and soil carbon, nitrogen, and phosphorus contents and ratios, as well as the soil salinity and soil organic carbon. The results revealed the following. (1) The leaf stoichiometric characteristics and soil properties of S. alterniflora differed significantly between tidal levels; for example, total carbon, nitrogen, soil organic carbon were detected at their highest levels at 3 km and lowest levels at 5 km. (2) Significant correlations were detected between the leaf stoichiometric characteristics and soil characteristics. Additionally, nitrogen limitation was evident in the study area, as indicated by the nitrogen–phosphorus ratio being less than 14 and the soil nitrogen–phosphorus ratio being less than 1. (3) Soil salinity and the soil carbon–nitrogen ratio were shown to be the key factors that affect the eco-stoichiometric characteristics of S. alterniflora. These findings furthered our understanding of the nutrient distribution mechanisms and invasion strategy of S. alterniflora and can thus be used to guide S. alterniflora control policies formulated by government management departments in China.

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

2018 ◽  
Vol 10 (8) ◽  
pp. 405 ◽  
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.

scholarly journals ORCHIDEE-SOM: Modeling soil organic carbon (SOC) and dissolved organic carbon (DOC) dynamics along vertical soil profiles in Europe

2017 ◽  
Author(s):  
Marta Camino-Serrano ◽  
Bertrand Guenet ◽  
Sebastiaan Luyssaert ◽  
Philippe Ciais ◽  
Vladislav Bastrikov ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Soil Carbon ◽  
Land Surface ◽  
Coniferous Forest ◽  
Soil Horizon ◽  
Surface Model ◽  
Model Parameters ◽  
Soc Stocks

Abstract. Current Land Surface Models (LSMs) typically represent soils in a very simplistic way, assuming soil organic carbon (SOC) as a bulk, thus impeding a correct representation of deep soil carbon dynamics. Moreover, LSMs generally neglect the production and export of dissolved organic carbon (DOC) from soils to rivers, leading to overestimations of the potential carbon sequestration on land. These common oversimplified processing of SOC in LSMs is partly responsible for the large uncertainty in the predictions of the soil carbon response to climate change. In this study, we present a new soil carbon module called ORCHIDEE-SOM, embedded within the land surface model ORCHIDEE, which is able to reproduce the DOC and SOC dynamics in a vertically discretized soil to two meters. The model includes processes of biological production and consumption of SOC and DOC, DOC adsorption on- and desorption from soil minerals, diffusion of SOC and DOC and DOC transport with water through and out of the soils to rivers. We evaluated ORCHIDEE-SOM against observations of DOC concentrations and SOC stocks from four European sites with different vegetation covers: a coniferous forest, a deciduous forest, a grassland and a cropland. The model was able to reproduce the SOC stocks along their vertical profiles at the four sites and the DOC concentrations within the range of measurements, with the exception of the DOC concentrations in the upper soil horizon at the coniferous forest. However, the model was not able to fully capture the temporal dynamics of DOC concentrations. Further model improvements should focus on a plant- and depth- dependent parameterization of the new input model parameters, such as the decomposition times of DOC and the microbial carbon use efficiency. We suggest that this new soil module, when parameterized for global simulations, will improve the representation of the global carbon cycle in LSMs, thus helping to constrain the predictions of the future SOC response to global warming.

Sign in / Sign up

Export Citation Format

Share Document