Soil organic carbon changes in cracking clay soils under cotton production as studied by carbon fractionation

1997 ◽  
Vol 48 (7) ◽  
pp. 1049 ◽  
Author(s):  
A. Conteh ◽  
G. J. Blair ◽  
R. D. B. Lefroy ◽  
D. A. Macleod
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Total Carbon ◽  
Clay Soils ◽  
Cotton Production ◽  
Labile Carbon ◽  
Fractionation Procedure ◽  
Wide Range ◽  
Carbon Management Index ◽  
Soil Carbon Fractions

This study examined soil carbon levels across a wide range of cracking clay soils used for growing cotton in Australia by using a simple carbon fractionation procedure. The soils studied included reference and cropped sites. The procedure employed determines soil carbon fractions based on their ease of oxidation to obtain the labile (CL) and non-labile (CNL) carbon components. Based on the total carbon (CT), labile carbon (CL), and non-labile carbon (CNL) of a cropped soil relative to a reference soil, various monitoring indices were developed. It was found that cultivation has generally led to a decrease in the organic carbon status of the soils. The effect of cultivation was found to be more pronounced in the CL and the carbon management index (CMI) than in the CT and CNL. The changes in the ratio of CL to CNL as a result of cultivation have been variable. The CMI has generally declined during cultivation, and since the CMI has incorporated the changes taking place in CT, CL, and CNL, the use of this index can provide very useful results in monitoring of organic matter status of soils.

The distribution and relative losses of soil organic carbon fractions in aggregate size fractions from cracking clay soils (Vertisols) under cotton production

Soil Research ◽  
1998 ◽  
Vol 36 (2) ◽  
pp. 257 ◽  
Author(s):  
A. Conteh ◽  
G. J. Blair
Keyword(s):  
Organic Carbon ◽  
Soil Organic Carbon ◽  
Aggregate Size ◽  
Light Fraction ◽  
Total Carbon ◽  
Clay Soils ◽  
Cotton Production ◽  
Carbon Fractions ◽  
Aggregate Fractions ◽  
Organic Carbon Fractions

The distribution and losses of organic carbon fractions in various aggregate sizes from cracking clay soils were studied to understand some factors associated with losses of soil organic carbon under cultivation. Five pairs of samples from cropped and adjacent uncropped (reference) soils were collected from 5 of the main cotton-growing regions of Australia. Five aggregate sizes were separated from each of these soils (<50 µm, 50-150 µm, 150-250 µm, 250-450 µm, and 450-500 µm). On each of these aggregate fractions, measurements were made for total carbon (CT), labile carbon by ease of oxidation (CL), d 13 C, total light fraction (LF), carbon content of light fraction (C%-LF), and the proportion of soil carbon in the light fraction (LF-C) calculated. CT and CL were found to increase with a decrease in aggregate size, whereas LF was found to decrease with a decrease in aggregate size. Losses of both CT and CL as a result of cultivation were higher in larger aggregates than in smaller aggregates. The δ13C of both the whole soil and the LF was higher in the cropped soil than in the reference soil. It was concluded that most of the organic matter present in the cracking clay soils used for cotton production is highly decomposed, and most of it is concentrated in the microaggregates of the soil.

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.

Soil organic carbon fractions in a Vertisol under irrigated cotton production as affected by burning and incorporating cotton stubble

Soil Research ◽  
1998 ◽  
Vol 36 (4) ◽  
pp. 655 ◽  
Author(s):  
A. Conteh ◽  
G. J. Blair ◽  
I. J. Rochester
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Organic Matter Content ◽  
Matter Content ◽  
Total Carbon ◽  
Cotton Production ◽  
Labile Carbon ◽  
Total N ◽  
The Difference ◽  
Organic Matter Fractions

The contribution of cotton stubble to the soil organic matter content of Vertisols under cotton production is not well understood. A 3-year experiment was conducted at the Australian Cotton Research Institute to study the effects of burning and incorporating cotton stubble on the recovery of fertiliser nitrogen (N), lint yield, and organic matter levels. This study reports on the changes in soil organic matter fractions as affected by burning and incorporating cotton stubble into the soil. Soil samples collected at the start and end of the 3-year experiment were analysed for total carbon (CT), total N (NT), and δ13C (a measure of 13C/12C isotopic ratios). Labile carbon (CL) was determined by ease of oxidation and non-labile carbon (CNL) was calculated as the difference between CT and CL. Based on the changes in CT, CL, and CNL, a carbon management index (CMI) was calculated. Further analyses were made for total polysaccharides (PT), labile polysaccharides (PL), and light fraction C (LF-C). Stubble management did not significantly affect the NT content of the soil. After 3 years, the stubble-incorporated plots had a significantly higher content of CT, CL, and polysaccharides. Incorporation of stubble into the soil increased the CMI by 41%, whereas burning decreased the CMI by 6%. The amount of LF-C obtained after 3 years in the stubble-incorporated soil was almost double that obtained in the stubble-burnt soil. It was concluded that for sustainable management of soil organic matter in the Vertisols used for cotton production, stubble produced in the system should be incorporated instead of burnt.

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.

Changes in soil chemical and physical properties following legumes and opportunity cropping on a cracking clay soil

1999 ◽  
Vol 39 (4) ◽  
pp. 445 ◽  
Author(s):  
R. D. Armstrong ◽  
B. J. Kuskopf ◽  
G. Millar ◽  
A. M. Whitbread ◽  
J. Standley
Keyword(s):  
Hydraulic Conductivity ◽  
Organic Carbon ◽  
Physical Properties ◽  
Soil Carbon ◽  
Total Nitrogen ◽  
The Other ◽  
Labile Carbon ◽  
Soil Hydraulic Conductivity ◽  
Penetrometer Resistance ◽  
Pasture Legumes

Incorporating legumes into the cropping system has been shown to significantly improve the nitrogen nutrition of cereal crops in Central Queensland. However, little is known about the effect of these legumes on the chemical and physical properties of soil. We examined changes in soil chemical (total nitrogen, organic carbon and pH) and physical (bulk density, cone penetrometer resistance and saturated hydraulic conductivity) properties following either continuous cropping (sorghum or mungbean) or pasture legumes (siratro, lucerne, lablab and desmanthus) over 4 years. Soil carbon was also fractionated using a KMnO4 oxidation procedure which classifies the soil carbon into either labile or non-labile pools. All pasture legumes except desmanthus increased soil total nitrogen in the topsoil (0–10 cm) after only 2 years compared with sorghum. Total nitrogen in the soil did not significantly change under mungbean. Soil organic carbon progressively increased under siratro, desmanthus and sorghum but remained unchanged under the other legumes. Before the experiment, the percentage of total soil carbon classified as labile (oxidised by 333 mmol KMnO4/L) ranged from 14 to 17%. The amount of labile carbon increased by 17% after 3 years of siratro, remained unchanged under desmanthus and sorghum, and decreased under the annual legumes and lucerne. Non-labile carbon remained either unchanged or increased under all legumes, whereas it tended to decrease after 3 consecutive sorghum crops. Soil pH was generally highest under sorghum and lowest under lablab. Soil after sorghum had higher bulk density and penetrometer resistance compared with the effect of legumes but these differences were comparatively small. Saturated hydraulic conductivity of the soil was much higher on the soil surface than at 10 cm. On the surface, soil hydraulic conductivity (saturated) values were generally lower following siratro and higher after sorghum than the other species. At 10 cm depth, soil hydraulic conductivity (saturated) was generally lower in sorghum and, to a lesser extent, in mungbean plots reflecting the significantly lower density of macropores under these crops. It was concluded that although all legumes generally enhanced the chemical and physical properties of the cracking clay, perennial legumes such as siratro would have a greater beneficial effect in the longer term than annual legumes.

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;

Spatial variability of organic and inorganic carbon stocks in Hungry Steppe (Uzbekistan)

2020 ◽  
Author(s):  
Sophia Demina ◽  
Viacheslav Vasenev ◽  
Kristina Ivashchenko ◽  
Inna Brianskaia ◽  
Bakhtiyor Pulatov ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Soil Carbon ◽  
Soil Salinity ◽  
Inorganic Carbon ◽  
Carbon Stocks ◽  
Total Carbon ◽  
Soil Inorganic Carbon ◽  
Organic And Inorganic Carbon ◽  
Soil Carbon Stocks ◽  
Soil Inorganic

&lt;p&gt;Desertification is an important soil treat, affecting soil functions and ecosystem services&amp;#160;&amp;#160; in arid and semiarid climate zones. Salinization is one of the principal processes which follows desertification and has a negative impact on soil properties and functions. Carbon sequestration is considered a principle soil function and the decline in soil carbon stocks in one of the main negative consequences of soil degradation. Soil salinization is caused by combination of natural factors (e.g. dry climate condition and high table of mineralized ground waters) and human activities such as improper water management. Globally, soils of the areas affected by salinization are considered to be poor in organic carbon due to low biomass and hampered microbiological activity. However, the contribution of inorganic carbon to the total carbon stocks in these areas can be comparable. Considering that soil inorganic carbon is more stable to mineralization compared to organic carbon, soil carbon stocks in saline landscape shall not be neglected.&lt;/p&gt;&lt;p&gt;Central Asian regions and especially the Aral Sea basin have been historically affected by desertification enhancing soil salinity. Hungry Steppe (Mirzachul) is an area of historical desertification and salinization, covering around 10000 km&lt;sup&gt;2&lt;/sup&gt; at the territories of Uzbekistan, South Kazakhstan and Tajikistan. The region has a sharp continental climate with large seasonal fluctuations. Dry and semidesertic steppe vegetation dominates the natural areas (mainly coincided with high soil salinity), whereas most of the areas is managed to produce cotton, perennial grasses, melons and gourds. Soils are dominated by serozems corresponding to Calcisols in WRB soil classification. The research aimed to analyze the effect of salinization on carbon stocks in Hungry Steppe. To achieve this aim, soil carbon stocks were estimated at the four collective farms, referred as Water Consumer Assiociations (WCAs) or &amp;#8216;shirkats&amp;#8217; in Syrdarya province: Khavast district in Yangier WCA, Mirzaobod district in Beruniy WCA&amp;#160; Oq Oltin district in Andijan WCA and Syrdarya district in Sobir&amp;#160; Rakhimov WCA. The selected sites belonged to different in land quality classes, based on the land evaluation survey carried out by the melioration expedition of the Ministry of Agriculture and Water Resources of Uzbekistan in 201,&amp;#160; from the lowest (Mirzaobod) to the highest (S. Rahimov). Soil pH, electroconductivity, chlorides, organic and inorganic carbon stocks and total nitrogen stocks were estimated for each of the areas. Although the internal variability in the analyzed parameters was high we clearly showed the highest stocks of soil inorganic carbon in the most salinized area, whereas the highest stocks of organic carbon were shown for the most fertile lands. However, we didn&amp;#8217;t ding significant difference in the total carbon stocks between the sites. It can be concluded that desertification has more effect on the redistribution of organic and inorganic forms of carbon, rather than on the total carbon stocks.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Acknowledgements &lt;/strong&gt;The experimental research was performed with the support of the Russian Foundation for Basic Research, Project # 18-54-41004 and Ministry of Innovation development of the Republic of Uzbekistan, Project # MRU-SQV 86/2017. Data analysis and mapping was supported by the RUDN project &amp;#8220;5-100&amp;#8221;.&lt;/p&gt;

Validation of method for determination total carbon, inorganic carbon and total organic carbon in marine waters

2018 ◽  
Vol 33 (1) ◽  
pp. 199-206
Author(s):  
Karolina Nowogrodzka ◽  
Grażyna Dembska ◽  
Katarzyna Galer-Tatarowicz
Keyword(s):  
Organic Carbon ◽  
Total Carbon ◽  
Marine Waters ◽  
Limit Of Quantification ◽  
Analysis Process ◽  
Wide Range ◽  
Repeatability And Reproducibility ◽  
Marine Institute ◽  
Inorganic And Organic

Validation is a process of setting parameters characterizing the proficiency of actions and limitations of a method and an assessment of its usefulness for particular purposes. As a result, it ensures that the analysis process is carried out in a reliable and precise way and gives reliable results. For the validation process marine water was used, as well as the addition of standard solutions. Uncertainty in the results, limit of quantification, precision, repeatability and reproducibility, recovery and accuracy of the method were obtained. The results of the validation of the method for determination of total inorganic and organic carbon in marine waters are discussed in this paper. For this purpose, a Shimadzu analyser TOC-L was used. The discussed method is based on infrared detection NDIR. A halogen scrubber type B was used for determined the compounds. This allowed the analysis time at the stage of the sample preparation to be shortened. It increased the absorption of salt contained in a sample, as a result of which, the dilution stage could be omitted, and the final result is affected by a smaller error. The method of the validation for determination of total inorganic and organic carbon received accreditation of the Polish Centre for Accreditation and joined a wide range of the analyses carried out in the Laboratory of the Department of Environment Protection of the Marine Institute in Gdańsk.

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.

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