ORCID Profile
0000-0002-6428-8555
Current Organisation
CSIRO
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Soil Sciences | Carbon Sequestration Science | Soil Biology | Soil Chemistry | Marine and Estuarine Ecology (incl. Marine Ichthyology) | Microbial Ecology | Soil Biology | Soil Chemistry (excl. Carbon Sequestration Science) | Terrestrial Ecology | Agricultural Land Management | Land Capability And Soil Degradation |
ANZSRC Socio-Economic Objective (SEO)
Climate Change Mitigation Strategies | Climate change | Ecosystem Assessment and Management of Coastal and Estuarine Environments | Farmland, Arable Cropland and Permanent Cropland Soils | Grain legumes | Coastal and Estuarine Soils | Wheat | Living resources (flora and fauna) | Integrated (ecosystem) assessment and management
Related Links
Publications
Which crops should be included in a carbon accounting system for Australian agriculture?
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/CP08428
Abstract: Dryland agriculture is both a potential source and potential sink for CO2 and other greenhouse gases. Many carbon accounting systems apply simple emissions factors to production units to estimate greenhouse gas (GHG) fluxes. However, in Australia, substantial variation in climate, soils, and management across Mha of field crop sowings and Mha of sown pastures in the intensive land use zone, provides substantial challenges for a national carbon accounting system, and simple emission factors are unlikely to apply across the region. In Australia a model framework has been developed that requires estimates of crop dry matter production and harvested yield as the first step to obtain carbon (residue) inputs. We use Australian Bureau of Statistics data to identify which crops would need to be included in such a carbon accounting system. Wheat, barley, lupin, and canola accounted for % of field crop sowings in Australia in 2006, and a total of 22 crops account for % of the sowing area in all States. In some States, only four or six crops can account for 99% of the cropping area. We provide a ranking of these crops for Australia and for each Australian State as a focus for the establishment of a comprehensive carbon accounting framework. Horticultural crops, although erse, are less important in terms of total area and thus C balances for generic viticulture, vegetables, and orchard fruit crops should suffice. The dataset of crop areas presented here is the most comprehensive account of crop sowings presented in the literature and provides a useful resource for those interested in Australian agriculture. The field crop rankings presented represent only the area of crop sowings and should not be taken as rankings of importance in terms of the magnitude of all GHG fluxes. This awaits a more detailed analysis of climate, soils, and management practices across each of the regions where the crops are grown and their relationships to CO2, nitrous oxide and methane fluxes. For pastures, there is a need for more detailed, up to date, spatially explicit information on the predominant sown pasture types across the Australian cropping belt before C balances for these can be more reliably modelled at the desired spatial scale.
Soil Security: Solving the Global Soil Crisis
Publisher: Wiley
Date: 28-10-2013
Solid-state 13C NMR analysis of size and density fractions of marine sediments: Insight into organic carbon sources and preservation mechanisms
Publisher: Elsevier BV
Date: 02-2006
Dispersed clay and organic matter in soil: their nature and associations
Publisher: CSIRO Publishing
Date: 1999
DOI: 10.1071/S98076
Abstract: Clay dispersion in soil results in structural instability and management problems. The aim of this study was to determine whether or not the easily dispersed colloidal materials differ in their properties from colloidal materials that do not disperse easily. Soil s les from the topsoil of sodic and non-sodic variants of an Alfisol under irrigated pasture (Kyabram, Victoria, Australia), and from the topsoil and subsoil of a sodic Alfisol under cultivation (Two Wells, South Australia) were fractionated into easily dispersed, moderately dispersed, and difficult to disperse clay, and silt, sand, and light fractions. As a proportion of total clay, easily dispersed clay content was greatest in the subsoil, and least in the Kyabram topsoils. In the topsoils, easily dispersed clay had larger particle size and lower cation exchange capacity than difficult to disperse clay, suggesting that high surface area and charge lead to increased inter-particle interactions and lower dispersibility. Easily dispersed clay had lower organic C contents than difficult to disperse clay. Organic matter was examined by 13C nuclear magnetic resonance, and the spectra were interpreted using major groups of biomolecules as model components. In all soils, organic matter in the easily dispersed clay fraction contained a high proportion of amino acids, suggesting that amino acids or proteins acted as dispersants. Difficult to disperse clay contained a high proportion of aliphatic materials in the topsoils, and carbohydrate in the subsoil, suggesting that these materials acted as water-stable glues. Selectivity for Na (KG) was negatively correlated with organic C content in the clay fractions. In the Kyabram soils, KG was greater in easily dispersed clay than in difficult to disperse clay. In Two Wells soil, clay with high KG appeared to have already moved out of the topsoil, into the subsoil. This work showed that variability in the nature of organic matter and clay particles has an important influence on clay dispersion in sodic and non-sodic soils.
Author Correction: The future of Blue Carbon science (Nature Communications, (2019), 10, 1, (3998), 10.1038/s41467-019-11693-w)
Publisher: Springer Science and Business Media LLC
Date: 08-11-2019
DOI: 10.1038/S41467-019-13126-0
Abstract: An amendment to this paper has been published and can be accessed via a link at the top of the paper.
Accounting for soil carbon sequestration in national inventories: a soil scientist’s perspective
Publisher: IOP Publishing
Date: 07-2010
Dissolved organic carbon chemistry and dynamics in contrasting forest and grassland soils
Publisher: Springer Science and Business Media LLC
Date: 06-2008
Topographic controls on black carbon accumulation in Alaskan black spruce forest soils: implications for organic matter dynamics
Publisher: Springer Science and Business Media LLC
Date: 05-02-2010
SCARIFICATION, FERTILIZATION AND HERBICIDE TREATMENT EFFECTS ON PLANTED CONIFERS AND SOIL FERTILITY
Publisher: Springer Science and Business Media LLC
Date: 1995
DOI: 10.1007/BF00029364
Prospects and problems of simple linear models for estimating symbiotic N-2 fixation by crop and pasture legumes (vol 329, pg 75, 2010)
Publisher: Springer Science and Business Media LLC
Date: 30-07-2011
Microbial community structure and residue chemistry during decomposition of shoots and roots of young and mature wheat (Triticum aestivum L.) in sand
Publisher: Wiley
Date: 20-07-2011
Consistent effects of biodiversity loss on multifunctionality across contrasting ecosystems.
Publisher: Springer Science and Business Media LLC
Date: 18-12-2018
DOI: 10.1038/S41559-017-0415-0
Abstract: Understanding how loss of bio ersity affects ecosystem functioning, and thus the delivery of ecosystem goods and services, has become increasingly necessary in a changing world. Considerable recent attention has focused on predicting how bio ersity loss simultaneously impacts multiple ecosystem functions (that is, ecosystem multifunctionality), but the ways in which these effects vary across ecosystems remain unclear. Here, we report the results of two 19-year plant ersity manipulation experiments, each established across a strong environmental gradient. Although the effects of plant and associated fungal ersity loss on in idual functions frequently differed among ecosystems, the consequences of bio ersity loss for multifunctionality were relatively invariant. However, the context-dependency of bio ersity effects also worked in opposing directions for different in idual functions, meaning that similar multifunctionality values across contrasting ecosystems could potentially mask important differences in the effects of bio ersity on functioning among ecosystems. Our findings highlight that an understanding of the relative contribution of species or functional groups to in idual ecosystem functions among contrasting ecosystems and their interactions (that is, complementarity versus competition) is critical for guiding management efforts aimed at maintaining ecosystem multifunctionality and the delivery of multiple ecosystem services.
Sediment and carbon deposition vary among vegetation assemblages in a coastal salt marsh
Publisher: Copernicus GmbH
Date: 17-08-2017
Abstract: Abstract. Coastal salt marshes are dynamic, intertidal ecosystems that are increasingly being recognised for their contributions to ecosystem services, including carbon (C) accumulation and storage. The survival of salt marshes and their capacity to store C under rising sea levels, however, is partially reliant upon sedimentation rates and influenced by a combination of physical and biological factors. In this study, we use several complementary methods to assess short-term (days) deposition and medium-term (months) accretion dynamics within a single marsh that contains three salt marsh vegetation types common throughout southeastern (SE) Australia.We found that surface accretion varies among vegetation assemblages, with medium-term (19 months) bulk accretion rates in the upper marsh rush (Juncus) assemblage (1.74 ± 0.13 mm yr−1) consistently in excess of estimated local sea-level rise (1.15 mm yr−1). Accretion rates were lower and less consistent in both the succulent (Sarcocornia, 0.78 ± 0.18 mm yr−1) and grass (Sporobolus, 0.88 ± 0.22 mm yr−1) assemblages located lower in the tidal frame. Short-term (6 days) experiments showed deposition within Juncus plots to be dominated by autochthonous organic inputs with C deposition rates ranging from 1.14 ± 0.41 mg C cm−2 d−1 (neap tidal period) to 2.37 ± 0.44 mg C cm−2 d−1 (spring tidal period), while minerogenic inputs and lower C deposition dominated Sarcocornia (0.10 ± 0.02 to 0.62 ± 0.08 mg C cm−2 d−1) and Sporobolus (0.17 ± 0.04 to 0.40 ± 0.07 mg C cm−2 d−1) assemblages.Elemental (C : N), isotopic (δ13C), mid-infrared (MIR) and 13C nuclear magnetic resonance (NMR) analyses revealed little difference in either the source or character of materials being deposited among neap versus spring tidal periods. Instead, these analyses point to substantial redistribution of materials within the Sarcocornia and Sporobolus assemblages, compared to high retention and preservation of organic inputs in the Juncus assemblage. By combining medium-term accretion quantification with short-term deposition measurements and chemical analyses, we have gained novel insights into above-ground biophysical processes that may explain previously observed regional differences in surface dynamics among key salt marsh vegetation assemblages. Our results suggest that Sarcocornia and Sporobolus assemblages may be particularly susceptible to changes in sea level, though quantification of below-ground processes (e.g. root production, compaction) is needed to confirm this.
Changes in soil carbon under long-term maize in monoculture and legume-based rotation
Publisher: Canadian Science Publishing
Date: 02-2001
DOI: 10.4141/S00-041
Abstract: Legume-based cropping systems could help to increase crop productivity and soil organic matter levels, thereby enhancing soil quality, as well as having the additional benefit of sequestering atmospheric C. To evaluate the effects of 35 yr of maize monoculture and legume-based cropping on soil C levels and residue retention, we measured organic C and 13 C natural abundance in soils under: fertilized and unfertilized maize (Zea mays L.), both in monoculture and legume-based [maize-oat (Avena sativa L.)-alfalfa (Medicago sativa L.)-alfalfa] rotations fertilized and unfertilized systems of continuous grass (Poa pratensis L.) and under forest. Solid state 13 C nuclear magnetic resonance (NMR) was used to chemically characterize the organic matter in plant residues and soils. Soils (70-cm depth) under maize cropping had about 30-40% less C, and those under continuous grass had about 16% less C, than those under adjacent forest. Qualitative differences in crop residues were important in these systems, because quantitative differences in net primary productivity and C inputs in the different agroecosystems did not account for observed differences in total soil C. Cropping sequence (i.e., rotation or monoculture) had a greater effect on soil C levels than application of fertilizer. The difference in soil C levels between rotation and monoculture maize systems was about 20 Mg C ha -1 . The effects of fertilization on soil C were small (~6 Mg C ha -1 ), and differences were observed only in the monoculture system. The NMR results suggest that the chemical composition of organic matter was little affected by the nature of crop residues returned to the soil. The total quantity of maize-derived soil C was different in each system, because the quantity of maize residue returned to the soil was different hence the maize-derived soil C ranged from 23 Mg ha -1 in the fertilized and 14 Mg ha -1 in the unfertilized monoculture soils (i.e., after 35 maize crops) to 6-7 Mg ha -1 in both the fertilized and unfertilized legume-based rotation soils (i.e., after eight maize crops). The proportion of maize residue C returned to the soil and retained as soil organic C (i.e., Mg maize-derived soil C/Mg maize residue) was about 14% for all maize cropping systems. The quantity of C3-C below the plow layer in legume-based rotation was 40% greater than that in monoculture and about the same as that under either continuous grass or forest. The soil organic matter below the plow layer in soil under the legume-based rotation appeared to be in a more biologically resistant form (i.e., higher aromatic C content) compared with that under monoculture. The retention of maize residue C as soil organic matter was four to five times greater below the plow layer than that within the plow layer. We conclude that residue quality plays a key role in increasing the retention of soil C in agroecosystems and that soils under legume-based rotation tend to be more “preservative” of residue C inputs, particularly from root inputs, than soils under monoculture. Key words: Soil carbon, 13 C natural abundance, 13 C nuclear magnetic resonance, maize cropping, legumes, root carbon
Mitigation of N2 O emissions from surface-irrigated cropping systems using water management and the nitrification inhibitor DMPP
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/SR15315
Abstract: Soils under irrigated agriculture are a significant source of nitrous oxide (N2O) owing to high inputs of nitrogen (N) fertiliser and water. This study investigated the potential for N2O mitigation by manipulating the soil moisture deficit through irrigation scheduling in combination with, and in comparison to, using the nitrification inhibitor, 3,4-dimethylpyrazole phosphate (DMPP). Lysimeter cores planted with wheat were fitted with automated chambers for continuous measurements of N2O fluxes. Treatments included conventional irrigation (CONV), reduced deficit irrigation (RED), CONV-DMPP and RED-DMPP. The total seasonal volume of irrigation water applied was constant for all treatments but the timing and quantity in in idual irrigation applications varied among treatments. 15N-labelled urea was used to track the source of N2O emissions and plant N uptake. The majority of N2O emissions occurred immediately after irrigations began on 1 September 2014. Applying RED and DMPP in idually slightly decreased N2O emissions but when applied in combination (RED-DMPP) the greatest reductions in N2O emissions were observed. There was no effect of treatments on plant N uptake, 15N recovery or yield possibly because the system was not N limited. Half of the plant N and 53% to 87% of N2O was derived from non-fertiliser sources in soil, highlighting the opportunity to further exploit this valuable N pool.
Workshop on the potential application of the Verified Carbon Standard Method VM0033 to Australia’s Emission Reduction Fund
Publisher: CSIRO
Date: 2019
Divergent responses of organic matter composition to incubation temperature
Publisher: Elsevier BV
Date: 12-2015
Significance of microbial activity in soils as demonstrated by solid-state 13C NMR
Publisher: American Chemical Society (ACS)
Date: 04-1990
DOI: 10.1021/ES00074A010
Sorption behaviour of per- and polyfluoroalkyl substances (PFASs) as affected by the properties of coastal estuarine sediments
Publisher: Elsevier BV
Date: 06-2020
Priorities for improving soil condition across Australia's agricultural landscapes
Publisher: CSIRO Agriculture and Food
Date: 2017
Soil carbon sequestration potential: A review for Australian agriculture
Publisher: CSIRO
Date: 2010
Quantifying carbon for agricultural soil management: from the current status toward a global soil information system
Publisher: Informa UK Limited
Date: 03-09-2019
The global significance of omitting soil erosion from soil organic carbon cycling schemes
Publisher: Springer Science and Business Media LLC
Date: 26-10-2015
DOI: 10.1038/NCLIMATE2829
Demineralization of marine and freshwater sediments for CP/MAS 13C NMR analysis
Publisher: Elsevier BV
Date: 05-2001
Aspects of the chemical structure of soil organic materials as revealed by solid-state 13C NMR spectroscopy
Publisher: Springer Science and Business Media LLC
Date: 02-1992
DOI: 10.1007/BF02402261
Long-term stabilization of crop residues and soil organic carbon affected by residue quality and initial soil pH
Publisher: Elsevier BV
Date: 06-2017
DOI: 10.1016/J.SCITOTENV.2017.02.199
Abstract: Residues differing in quality and carbon (C) chemistry are presumed to contribute differently to soil pH change and long-term soil organic carbon (SOC) pools. This study examined the liming effect of different crop residues (canola, chickpea and wheat) down the soil profile (0-30cm) in two sandy soils differing in initial pH as well as the long-term stability of SOC at the amended layer (0-10cm) using mid-infrared (MIR) and solid-state
Solid-state 15N NMR analysis of highly 15N-enriched plant materials
Publisher: Springer Science and Business Media LLC
Date: 08-2005
Is the fate of glucose-derived carbon more strongly driven by nutrient availability, soil texture, or microbial biomass size?
Publisher: Elsevier BV
Date: 12-2016
Land‐use contrasts reveal instability of subsoil organic carbon
Publisher: Wiley
Date: 25-06-2016
DOI: 10.1111/GCB.13379
Abstract: Subsoils contain large amounts of organic carbon which is generally believed to be highly stable when compared with surface soils. We investigated subsurface organic carbon storage and dynamics by analysing organic carbon concentrations, fractions and isotopic values in 78 s les from 12 sites under different land-uses and climates in eastern Australia. Despite radiocarbon ages of several millennia in subsoils, contrasting native systems with agriculturally managed systems revealed that subsurface organic carbon is reactive on decadal timeframes to land-use change, which leads to large losses of young carbon down the entire soil profile. Our results indicate that organic carbon storage in soils is input driven down the whole profile, challenging the concept of subsoils as a repository of stable organic carbon.
A Global Assessment of the Chemical Recalcitrance of Seagrass Tissues: Implications for Long-Term Carbon Sequestration
Publisher: Frontiers Media SA
Date: 13-06-2017
The relationships between land uses, soil management practices, and soil carbon fractions in South Eastern Australia
Publisher: Elsevier BV
Date: 12-2014
Plant litter composition and stable isotope signatures vary during decomposition in blue carbon ecosystems
Publisher: Springer Science and Business Media LLC
Date: 02-2022
DOI: 10.1007/S10533-022-00890-3
Abstract: The ratio of isotopes of carbon ( 13 C: 12 C or δ 13 C) and nitrogen ( 15 N: 14 N or δ 15 N) are common indicators of the flow and storage of organic matter in coastal wetland research. Effective use of these indicators requires quantification and understanding of: (1) the variability of isotope signatures of potential organic matter source materials and (2) the influence of organic matter decomposition on isotopic signatures. While it is well-established that organic matter characteristics change during the decomposition process, there has been little direct quantification of any concurrent shifts in isotope signatures for coastal detritus. In this study, we addressed this by quantifying: (1) shifts in s le composition using solid-state 13 C Nuclear Magnetic Resonance (NMR) spectroscopy and (2) shifts in δ 13 C and δ 15 N signatures of coastal plant tissues from field litterbag experiments. We observed significant shifts in 13 C NMR spectra across the course of deployment for all four plant tissues assessed (leaves of mangrove Avicennia marina branchlets of supratidal tree Casuarina glauca leaf wrack and roots/rhizomes of the seagrass Zostera muelleri ), driven largely by the preferential loss of labile constituents and concentration of more resistant macromolecules, such as lignin and leaf waxes. While there were shifts in isotope ratios for all species, these varied in direction and magnitude among species, tissue type and isotopes. This included δ 13 C enrichments of up to 3.1‰ and 2.4‰ in leaves of A. marina , and branchlets of C. glauca , respectively, but δ 13 C depletions of up to 4.0‰ for Z. muelleri . Shifts in δ 15 N varied among species and tissue types, with few clear temporal patterns. Partial least squares regression analyses showed that some tissue isotope signatures can be reliably predicted on the basis of s le composition ( 13 C NMR spectra), however, multiple inter- and intra-species variations preclude a simple explanation of isotopic signature shifts on the basis of plant-material molecular shifts alone. Further, we cannot preclude the potential influence of microbe-associated organic matter on s le composition or isotopic signatures. Our findings emphasise the importance of considering decomposition effects on stable isotope signatures in blue carbon ecosystems. Isotope approaches will remain a valuable tool in coastal ecosystem research, but require robust experimental approaches (including appropriate use of decomposed end-members or fractionation correction factors quantification of microbial organic matter) and quantification of decomposition dynamics for specific plant tissues and environmental settings.
Baseline map of organic carbon in Australian soil to support national carbon accounting and monitoring under climate change
Publisher: Wiley
Date: 28-04-2014
DOI: 10.1111/GCB.12569
Field measurements of bare soil evaporation and crop transpiration, and transpiration efficiency, for rainfed grain crops in Australia – a review
Publisher: Elsevier BV
Date: 06-2018
Carbon chemistry and mineralization of peat soils from the Australian Alps
Publisher: Wiley
Date: 21-02-2012
Impact of Remote Protonation on 13C CPMAS NMR Quantitation of Charred and Uncharred Wood
Publisher: Elsevier BV
Date: 08-2002
Abstract: The impact of inefficient cross polarization (long TCH values), caused by long 13C-1H internuclear distances, on 13C CPMAS NMR spectra of charred and uncharred woods is determined by simultaneously fitting data from complementary variable spin lock and variable contact time experiments. As expected, the impact is minimal for uncharred woods, but is very significant for the charred woods. Quantification of the decrease in CPMAS signal intensity caused by both inefficient cross polarization and rapid T1rhoH relaxation is achieved using an advanced spin counting methodology, for which the term "spin accounting" is proposed. 13C CPMAS NMR observabilities determined using the spin accounting methodology were close to 100% for the uncharred s les, and 69-82% for the charred s les. This represents a large improvement on the 30-40% observabilities determined using other spin counting techniques. Furthermore, it is shown that remote protonation and rapid T1rhoH relaxation are roughly equally responsible for the low signal intensity of standard (I ms contact time) 13C CPMAS spectra of charcoal.
Measurement of soil carbon oxidation state and oxidative ratio by 13C nuclear magnetic resonance
Publisher: American Geophysical Union (AGU)
Date: 19-05-2009
DOI: 10.1029/2008JG000803
Exploring how fire spread mode shapes the composition of pyrogenic carbon from forest litter fuels using solid state 13C nuclear magnetic resonance spectroscopy: a combustion wind tunnel study
Publisher: Elsevier BV
Date: 2020
DOI: 10.1016/J.SCITOTENV.2019.134306
Abstract: In this study, solid state
Sampling soil organic carbon to detect change over time
Publisher: CSIRO
Date: 2013
Determination of T1ρH Relaxation Rates in Charred and Uncharred Wood and Consequences for NMR Quantitation
Publisher: Elsevier BV
Date: 08-2002
Abstract: The performance of three different techniques for determining proton rotating frame relaxation rates (T1rhoH) in charred and uncharred woods is compared. The variable contact time (VCT) experiment is shown to over-estimate T1rhoH. particularly for the charred s les, due to the presence of slowly cross-polarizing 13C nuclei. The variable spin (VSL) or delayed contact experiment is shown to overcome these problems however, care is needed in the analysis to ensure rapidly relaxing components are not overlooked. T1rhoH is shown to be non-uniform for both charred and uncharred wood s les a rapidly relaxing component (T1rhoH = 0.46-1.07 ms) and a slowly relaxing component (T1rhoH = 3.58-7.49) is detected in each s le. T1rhoH for each component generally decreases with heating temperature (degree of charring) and the proportion of rapidly relaxing component increases. Direct T1rhoH determination (via 1H detection) shows that all s les contain an even faster relaxing component (0.09-0.24 ms) that is virtually undetectable by the indirect (VCT and VSL) techniques. A new method for correcting for T1rhoH signal losses in spin counting experiments is developed to deal with the rapidly relaxing component detected in the VSL experiment. Implementation of this correction increased the proportion of potential 13C CPMAS NMR signal that can be accounted for by up to 50% for the charred s les. An even greater proportion of potential signal can be accounted for if the very rapidly relaxing component detected in the direct T1rhoH determination is included however, it must be kept in mind that this experiment also detects 1H pools which may not be involved in 1H-13C cross-polarization.
Biochar differentially affects the cycling and partitioning of low molecular weight carbon in contrasting soils
Publisher: Elsevier BV
Date: 2015
Stocks, composition and vulnerability to loss of soil organic carbon predicted using mid-infrared spectroscopy
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR17221
Abstract: Developing a routine and cost effective capability for measuring soil organic carbon (SOC) content and composition will allow identification of land management practices with a potential to maintain or enhance SOC stocks. Coupling SOC content data and mid-infrared (MIR) spectra through the application of partial least-squares regression (PLSR) analyses has been used to develop such a prediction capability. The objective of this study was to determine whether MIR/PLSR analyses provide accurate estimates of the content and composition of SOC that can be used to quantify SOC stocks and its potential vulnerability to loss. Soil was collected from a field trial incorporating a range of land use (pasture, arable cropping and bare fallow) and tillage (intensive, minimum and no tillage) treatments over a nine-year period. The SOC content was measured by dry combustion analysis. Particulate organic carbon was separated from other forms of carbon on the basis of particle size (SOC in the µm fraction). Resistant organic carbon was quantified using solid-state 13C nuclear magnetic resonance. The MIR/PLSR algorithms were successfully developed to predict the natural logarithms of the contents of SOC and POC in the collected soils. With initial calibration, a single MIR analysis could be used in conjunction with PLSR algorithms to predict the content of SOC and its allocation to component fractions. The MIR/PLSR predicted SOC contents provided reliable estimates of the impact of agricultural management on the 0–25-cm SOC stocks, as well as an indication of the vulnerability of SOC to loss. Development of this capability will facilitate the rapid and cost effective collection of SOC content data for detecting the impact of agricultural management treatments on SOC stocks, composition and potential vulnerability to change.
Soils and climate change: potential impacts on carbon stocks and greenhouse gas emissions, and future research for Australian agriculture
Publisher: CSIRO Publishing
Date: 2012
DOI: 10.1071/CP11170
Abstract: Organic carbon and nitrogen found in soils are subject to a range of biological processes capable of generating or consuming greenhouse gases (CO2, N2O and CH4). In response to the strong impact that agricultural management can have on the amount of organic carbon and nitrogen stored in soil and their rates of biological cycling, soils have the potential to reduce or enhance concentrations of greenhouse gases in the atmosphere. Concern also exists over the potential positive feedback that a changing climate may have on rates of greenhouse gas emission from soil. Climate projections for most of the agricultural regions of Australia suggest a warmer and drier future with greater extremes relative to current climate. Since emissions of greenhouse gases from soil derive from biological processes that are sensitive to soil temperature and water content, climate change may impact significantly on future emissions. In this paper, the potential effects of climate change and options for adaptation and mitigations will be considered, followed by an assessment of future research requirements. The paper concludes by suggesting that the ersity of climate, soil types, and agricultural practices in place across Australia will make it difficult to define generic scenarios for greenhouse gas emissions. Development of a robust modelling capability will be required to construct regional and national emission assessments and to define the potential outcomes of on-farm management decisions and policy decisions. This model development will require comprehensive field datasets to calibrate the models and validate model outputs. Additionally, improved spatial layers of model input variables collected on a regular basis will be required to optimise accounting at regional to national scales.
Mid-infrared spectra predict nuclear magnetic resonance spectra of soil carbon
Publisher: Elsevier BV
Date: 06-2015
Factors affecting the measurement of soil pH buffer capacity: approaches to optimize the methods
Publisher: Wiley
Date: 27-10-2015
DOI: 10.1111/EJSS.12195
Evaluating pyrolysis–GC/MS and 13C CPMAS NMR in conjunction with a molecular mixing model of the Penido Vello peat deposit, NW Spain
Publisher: Elsevier BV
Date: 07-2007
Accumulation and attrition of peat soils in the Australian Alps: isotopic dating evidence
Publisher: Wiley
Date: 08-11-2012
Measuring and modelling yield and water budget components of wheat crops in coarse-textured soils with chemical constraints
Publisher: Elsevier BV
Date: 12-2003
Soil salinity decreases global soil organic carbon stocks
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2012.08.028
Abstract: Saline soils cover 3.1% (397 million hectare) of the total land area of the world. The stock of soil organic carbon (SOC) reflects the balance between carbon (C) inputs from plants, and losses through decomposition, leaching and erosion. Soil salinity decreases plant productivity and hence C inputs to the soil, but also microbial activity and therefore SOC decomposition rates. Using a modified Rothamsted Carbon model (RothC) with a newly introduced salinity decomposition rate modifier and a plant input modifier we estimate that, historically, world soils that are currently saline have lost an average of 3.47 tSOC ha(-1) since they became saline. With the extent of saline soils predicted to increase in the future, our modelling suggests that world soils may lose 6.8 Pg SOC due to salinity by the year 2100. Our findings suggest that current models overestimate future global SOC stocks and underestimate net CO2 emissions from the soil-plant system by not taking salinity effects into account. From the perspective of enhancing soil C stocks, however, given the lower SOC decomposition rate in saline soils, salt tolerant plants could be used to sequester C in salt-affected areas.
Effects of clay mineralogy and hydrous iron oxides on labile organic carbon stabilisation
Publisher: Elsevier BV
Date: 03-2012
Assessing the extent of decomposition of natural organic materials using solid-state 13C NMR spectroscopy
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/S97004
Abstract: Solid-state 13C nuclear magnetic resonance (NMR) spectroscopy has become an important tool for examining the chemical structure of natural organic materials and the chemical changes associated with decomposition. In this paper, solid-state 13C NMR data pertaining to changes in the chemical composition of a erse range of natural organic materials, including wood, peat, composts, forest litter layers, and organic materials in surface layers of mineral soils, were reviewed with the objective of deriving an index of the extent of decomposition of such organic materials based on changes in chemical composition. Chemical changes associated with the decomposition of wood varied considerably and were dependent on a strong interaction between the species of wood examined and the species composition of the microbial decomposer community, making the derivation of a single general index applicable to wood decomposition unlikely. For the remaining forms of natural organic residues, decomposition was almost always associated with an increased content of alkyl C and a decreased content of O-alkyl C. The concomitant increase and decrease in alkyl and O-alkyl C contents, respectively, suggested that the ratio of alkyl to O-alkyl carbon (A/O-A ratio) may provide a sensitive index of the extent of decomposition. Contrary to the traditional view that humic substances with an aromatic core accumulate as decomposition proceeds, changes in the aromatic region were variable and suggested a relationship with the activity of lignin-degrading fungi. The A/O-A ratio did appear to provide a sensitive index of extent of decomposition provided that its use was restricted to situations where the organic materials were derived from a common starting material. In addition, the potential for adsorption of highly decomposable materials on mineral soil surfaces and the impacts which such an adsorption may have on bioavailability required consideration when the A/O-A ratio was used to assess the extent of decomposition of organic materials found in mineral soils.
Soil carbon sequestration potential of permanent pasture and continuous cropping soils in New Zealand
Publisher: Wiley
Date: 16-05-2017
DOI: 10.1111/GCB.13720
Abstract: Understanding soil organic carbon (SOC) sequestration is important to develop strategies to increase the SOC stock and, thereby, offset some of the increases in atmospheric carbon dioxide. Although the capacity of soils to store SOC in a stable form is commonly attributed to the fine (clay + fine silt) fraction, the properties of the fine fraction that determine the SOC stabilization capacity are poorly known. The aim of this study was to develop an improved model to estimate the SOC stabilization capacity of Allophanic (Andisols) and non-Allophanic topsoils (0-15 cm) and, as a case study, to apply the model to predict the sequestration potential of pastoral soils across New Zealand. A quantile (90th) regression model, based on the specific surface area and extractable aluminium (pyrophosphate) content of soils, provided the best prediction of the upper limit of fine fraction carbon (FFC) (i.e. the stabilization capacity), but with different coefficients for Allophanic and non-Allophanic soils. The carbon (C) saturation deficit was estimated as the difference between the stabilization capacity of in idual soils and their current C concentration. For long-term pastures, the mean saturation deficit of Allophanic soils (20.3 mg C g
Organic Carbon Composition of Marine Sediments: Effect of Oxygen Exposure on Oil Generation Potential
Publisher: American Association for the Advancement of Science (AAAS)
Date: 05-10-2001
Abstract: Anaerobic sedimentary conditions have traditionally been linked to the generation of the source rocks for petroleum formation. However, the influence of sedimentary redox conditions on the composition of freshly deposited organic matter (OM) is not clear. We assessed the effect of in situ exposure time to oxic conditions on the composition of OM accumulating in different coastal and deep-sea sediments using solid-state 13 C nuclear magnetic resonance (NMR). 13 C NMR spectra were resolved into mixtures of model components to distinguish between alkyl carbon present in protein and nonprotein structures. There is an inverse relation between the length of exposure to oxic conditions and the relative abundance of nonprotein alkyl (alkyl NP ) carbon, whose concentration is two orders of magnitude higher in coastal sediments with short exposure times than in deep-sea sediments with long exposure times. All alkyl NP -rich s les contain a physically separate polymethylene component similar in composition to algaenans and kerogens in type I oil shales. The duration of exposure to oxic conditions appears to directly influence the quality and oil generation potential of OM in marine shales.
Rapid prediction of particulate, humus and resistant fractions of soil organic carbon in reforested lands using infrared spectroscopy
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.JENVMAN.2017.02.013
Abstract: Reforestation of agricultural lands with mixed-species environmental plantings can effectively sequester C. While accurate and efficient methods for predicting soil organic C content and composition have recently been developed for soils under agricultural land uses, such methods under forested land uses are currently lacking. This study aimed to develop a method using infrared spectroscopy for accurately predicting total organic C (TOC) and its fractions (particulate, POC humus, HOC and resistant, ROC organic C) in soils under environmental plantings. Soils were collected from 117 paired agricultural-reforestation sites across Australia. TOC fractions were determined in a subset of 38 reforested soils using physical fractionation by automated wet-sieving and
Decomposition dynamics of plant materials in relation to nitrogen availability and biochemistry determined by NMR and wet-chemical analysis
Publisher: Elsevier BV
Date: 12-2004
STRUCTURAL AMELIORATION OF A SOUTH AUSTRALIAN RED-BROWN EARTH USING CALCIUM AND ORGANIC AMENDMENTS
Publisher: CSIRO Publishing
Date: 1994
DOI: 10.1071/SR9940571
Abstract: The ability of wheat straw, gypsum and agricultural lime to ameliorate the unstable structural condition of a degraded red-brown earth located at the Waite Agricultural Research Institute, South Australia, was investigated in a field experiment lasting 5 years. Wheat straw was added at rates of 0, 5 and 10 t ha-1 y-1, and gypsum and agricultural lime were added at rates of 3.4 and 2.0 t ha-1 y-1 respectively. Most of the measurements were taken on s les collected after three and four consecutive years of treatment applications, but some were taken one year after the fifth and final application of the treatments. The amount of water-stable macroaggregation in the top 10 cm increased with increasing rate of wheat straw application. Addition of agricultural lime incorporated with straw temporarily increased macroaggregate stability to a greater extent than was observed with either amendment alone. The proportion of the soil surface occupied by macropores was also increased significantly by addition of agricultural lime, and this was attributed to a stimulation of biological activity in the soil due to the increased soil pH. Density fractionation of the soil suggested the turnover of the added wheat straw in the lime-treated soil was greater than in the gypsum-treated and control soils. Addition of gypsum decreased the content of mechanically dispersible clay by modifying the electrolyte concentration and composition, but was unable to completely resist the dispersive tendencies created by the decomposing organic residues. The high rates of wheat straw incorporated in the top 10 cm caused significant dispersion in the top 20 cm, which was thought to have mobilized clay particles causing them to move downward, resulting in pore blockage and the consequent lowering of hydraulic conductivity in the zone immediately below.
Solid state CP/MAS 13C N.M.R. analysis of particle size and density fractions of a soil incubated with uniformly labelled 13C-glucose
Publisher: CSIRO Publishing
Date: 1990
DOI: 10.1071/SR9900193
Abstract: A soil incubated for 34 days in the absence (control) and presence (treated) of uniformly labelled 13C-glucose was dispersed using an ultrasonic probe and fractionated by sedimentation in water and a polytungstate solution of density 2.0 Mg m3 . The residual substrate carbon was concentrated in the clay and light fractions. Solid state CP/MAS 13C n.m.r. (cross polarization/magic angle spinning 13c nuclear magnetic resonance) spectroscopy was used to characterize the chemical structure of the native soil organic carbon and the residual substrate carbon in the fractions of the control and treated soils. To obtain quantitative results it was essential to determine the spin lattice relaxation times in the rotating frame, T1pH, of the in idual carbon types in the spectra as the relaxation behaviour of the native organic materials in the clay fraction was substantially different from that of the residual substrate carbon. After correcting for T1pH effects, a significant linear relationship existed between the signal intensity and 13C content of the s les. This enabled the content, expressed in �mol 13C g-1 fraction, of each type of carbon in the fractions to be calculated. The residual substrate carbon was found to accumulate in predominantly alkyl and O-alkyl structures in both fractions. However, significant amounts of acetal and carboxyl carbon were also observed in the clay fraction. Little if any aromatic or phenolic carbon was synthesized by the soil microorganisms utilizing substrate carbon. Dipolar dephasing CP/MAS 13C n.m.r. experiments were also performed and allowed the proportion of each type of carbon which was protonated and nonprotonated to be estimated. Essentially all of the O-alkyl and acetal carbon, 25-40% of the aromatic carbon and 66-80% of the alkyl carbon was protonated in the fractions isolated from the treated soil
Environmental and edaphic drivers of bacterial communities involved in soil N-cycling
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR08126
Abstract: The cycling of N in soil is supported both directly and indirectly by numerous microbial processes. These processes affect ecosystem fertility, but can also generate forms of N which have detrimental environmental impacts, such as N2O. Understanding drivers of biological communities involved in key N-transformations is therefore of much interest. The effects of physicochemical and environmental properties on the relative size (abundance within total DNA pool) of biological communities involved in 3 key N transformations were investigated. Soils from 14 locations spanning a rainfall gradient across 3 agricultural regions (Clare, Mallee, Balaclava) were s led, with s les taken from the surface and at depth from each site. Based on PCA of physicochemical and environmental properties, the soils fell into 2 distinct groupings: Clare and Mallee + Balaclava ‘types’. The abundance of functional genes involved in N2 fixation (nifH), ammonia oxidation (amoA), and nitrate reduction (narG) was quantified in DNA extracted from the soils using real-time PCR. The abundance of the nifH gene varied significantly with site (P = 0.03) but not depth, and no regional association with nifH gene abundance was found. Multivariate analysis indicated that the abundance of nifH was positively correlated with soil total C (ρ = 0.382 P = 0.006). Similarly, the abundance of narG varied with site (P 0.001) and not soil depth. The abundance of narG was positively correlated with increasing rainfall (ρ = 0.417 P = 0.002). The abundance of amoA did not significantly vary between soils, but significantly decreased with soil depth (P = 0.006). The abundance of amoA was negatively correlated with soil electrical conductivity and positively with organic C (combined ρ = 0.44 P = 0.003). Whereas there was no relationship between the abundance of nifH and amoA or narG, the abundance of amoA was positively correlated with the abundance of narG (P 0.001). These results indicate that the abundance of the N cycling genes is independently affected by different physicochemical or environmental properties. The interactions between soil, environment, and the functionally significant biological communities they support are complex. To gain fuller understanding of soil N cycling, the ecology of the various biological components affecting N-transformations must be investigated simultaneously.
Dynamics of sediment carbon stocks across intertidal wetland habitats of Moreton Bay, Australia
Publisher: Wiley
Date: 16-05-2017
DOI: 10.1111/GCB.13722
Abstract: Coastal wetlands are known for high carbon storage within their sediments, but our understanding of the variation in carbon storage among intertidal habitats, particularly over geomorphological settings and along elevation gradients, is limited. Here, we collected 352 cores from 18 sites across Moreton Bay, Australia. We assessed variation in sediment organic carbon (OC) stocks among different geomorphological settings (wetlands within riverine settings along with those with reduced riverine influence located on tide-dominated sand islands), across elevation gradients, with distance from shore and among habitat and vegetation types. We used mid-infrared (MIR) spectroscopy combined with analytical data and partial least squares regression to quantify the carbon content of ~2500 sediment s les and provide fine-scale spatial coverage of sediment OC stocks to 150 cm depth. We found sites in river deltas had larger OC stocks (175-504 Mg/ha) than those in nonriverine settings (44-271 Mg/ha). Variation in OC stocks among nonriverine sites was high in comparison with riverine and mixed geomorphic settings, with sites closer to riverine outflow from the east and south of Moreton Bay having higher stocks than those located on the sand islands in the northwest of the bay. Sediment OC stocks increased with elevation within nonriverine settings, but not in riverine geomorphic settings. Sediment OC stocks did not differ between mangrove and saltmarsh habitats. OC stocks did, however, differ between dominant species across the research area and within geomorphic settings. At the landscape scale, the coastal wetlands of the South East Queensland catchments (17,792 ha) are comprised of approximately 4,100,000-5,200,000 Mg of sediment OC. Comparatively high variation in OC storage between riverine and nonriverine geomorphic settings indicates that the availability of mineral sediments and terrestrial derived OC may exert a strong influence over OC storage potential across intertidal wetland systems.
Simulation of salinity effects on past, present, and future soil organic carbon stocks
Publisher: American Chemical Society (ACS)
Date: 11-01-2012
DOI: 10.1021/ES2027345
Abstract: Soil organic carbon (SOC) models are used to predict changes in SOC stocks and carbon dioxide (CO(2)) emissions from soils, and have been successfully validated for non-saline soils. However, SOC models have not been developed to simulate SOC turnover in saline soils. Due to the large extent of salt-affected areas in the world, it is important to correctly predict SOC dynamics in salt-affected soils. To close this knowledge gap, we modified the Rothamsted Carbon Model (RothC) to simulate SOC turnover in salt-affected soils, using data from non-salt-affected and salt-affected soils in two agricultural regions in India (120 soils) and in Australia (160 soils). Recently we developed a decomposition rate modifier based on an incubation study of a subset of these soils. In the present study, we introduce a new method to estimate the past losses of SOC due to salinity and show how salinity affects future SOC stocks on a regional scale. Because salinity decreases decomposition rates, simulations using the decomposition rate modifier for salinity suggest an accumulation of SOC. However, if the plant inputs are also adjusted to reflect reduced plant growth under saline conditions, the simulations show a significant loss of soil carbon in the past due to salinization, with a higher average loss of SOC in Australian soils (55 t C ha(-1)) than in Indian soils (31 t C ha(-1)). There was a significant negative correlation (p < 0.05) between SOC loss and osmotic potential. Simulations of future SOC stocks with the decomposition rate modifier and the plant input modifier indicate a greater decrease in SOC in saline than in non-saline soils under future climate. The simulations of past losses of SOC due to salinity were repeated using either measured charcoal-C or the inert organic matter predicted by the Falloon et al. equation to determine how much deviation from the Falloon et al. equation affects the amount of plant inputs generated by the model for the soils used in this study. Both sets of results suggest that saline soils have lost carbon and will continue to lose carbon under future climate. This demonstrates the importance of both reduced decomposition and reduced plant input in simulations of future changes in SOC stocks in saline soils.
Facilitating entry to land sector carbon abatement projects: the LOOC-C tool
Publisher: Informa UK Limited
Date: 30-10-2023
Residue chemistry and microbial community structure during decomposition of eucalypt, wheat and vetch residues
Publisher: Elsevier BV
Date: 09-2009
A depositional history of particulate organic carbon in a floodplain lake from the lower Ob’ River, Siberia
Publisher: Elsevier BV
Date: 09-2011
Development of a southern hemisphere subtropical wetland (Welsby Lagoon, south-east Queensland, Australia) through the last glacial cycle
Publisher: Elsevier BV
Date: 12-2018
Carbon decomposition processes in a peat from the Australian Alps
Publisher: Wiley
Date: 15-03-2010
VARIABILITY IN HARVEST INDEX OF GRAIN CROPS AND POTENTIAL SIGNIFICANCE FOR CARBON ACCOUNTING: EXAMPLES FROM AUSTRALIAN AGRICULTURE
Publisher: Elsevier
Date: 2010
The link between peat hydrology and decomposition: Beyond von Post
Publisher: Elsevier BV
Date: 02-2013
Contribution of soluble and insoluble fractions of agricultural residues to short-term pH changes
Publisher: Wiley
Date: 09-2011
Introducing a decomposition rate modifier in the rothamsted carbon model to predict soil organic carbon stocks in saline soils
Publisher: American Chemical Society (ACS)
Date: 30-06-2011
DOI: 10.1021/ES200515D
Abstract: Soil organic carbon (SOC) models such as the Rothamsted Carbon Model (RothC) have been used to estimate SOC dynamics in soils over different time scales but, until recently, their ability to accurately predict SOC stocks/carbon dioxide (CO(2)) emissions from salt-affected soils has not been assessed. Given the large extent of salt-affected soils (19% of the 20.8 billion ha of arable land on Earth), this may lead to miss-estimation of CO(2) release. Using soils from two salt-affected regions (one in Punjab, India and one in South Australia), an incubation study was carried out measuring CO(2) release over 120 days. The soils varied both in salinity (measured as electrical conductivity (EC) and calculated as osmotic potential using EC and water content) and sodicity (measured as sodium adsorption ratio, SAR). For soils from both regions, the osmotic potential had a significant positive relationship with CO(2)-C release, but no significant relationship was found between SAR and CO(2)-C release. The monthly cumulative CO(2)-C was simulated using RothC. RothC was modified to take into account reductions in plant inputs due to salinity. A subset of non-salt-affected soils was used to derive an equation for a "lab-effect" modifier to account for changes in decomposition under lab conditions and this modifier was significantly related with pH. Using a subset of salt-affected soils, a decomposition rate modifier (as a function of osmotic potential) was developed to match measured and modelled CO(2)-C release after correcting for the lab effect. Using this decomposition rate modifier, we found an agreement (R(2) = 0.92) between modelled and independently measured data for a set of soils from the incubation experiment. RothC, modified by including reduced plant inputs due to salinity and the salinity decomposition rate modifier, was used to predict SOC stocks of soils in a field in South Australia. The predictions clearly showed that SOC stocks are reduced in saline soils. Therefore both the decomposition rate modifier and plant input modifier should be taken into account when accounting for SOC turnover in saline soils. Since modeling has previously not accounted for the impact of salinity, our results suggest that previous predictions may have overestimated SOC stocks.
Combining management based indices with environmental parameters to explain regional variation in soil carbon under dryland cropping in South Australia
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13156
Abstract: Identifying drivers of variation in soil organic carbon (OC) at a regional scale is often h ered by a lack of historical management information. Focusing on red-brown-earth soils (Chromosol) under dryland agriculture in the Mid-North and Eyre Peninsula of South Australia, our aims were 2-fold: (i) to provide a baseline of soil OC stocks (0.3 m) and OC fractions (mid-infrared predictions of particulate, humus, and resistant OC in 0.1 m s les) in cropping and crop-pasture systems and (ii) to evaluate whether the inclusion of management-based indices could assist in explaining regional-level variation in OC stocks and fractions. Soil OC stocks in both regions varied ~20 Mg ha–1, with higher OC stocks in the Mid-North (38 Mg ha–1) than the Eyre Peninsula (29.1 Mg ha–1). The humus OC fraction was the dominant fraction, while the particulate OC was the most variable. Environmental variables only partially explained soil OC variability, with vapour pressure deficit (VPD) offering the greatest potential and likely acting as an integrator of temperature and moisture on plant growth and decomposition processes. Differences between broad-scale cropping and crop–pasture systems were limited. In the Mid-North, variability in soil OC stocks and fractions was high, and could not be explained by environmental or management variables. Higher soil OC concentrations (0.1 m) in the Eyre Peninsula cropping than crop–pasture soils were largely accounted for in the particulate OC fraction and are therefore unlikely to represent a long-term stable OC pool. Use of the management data in index format added some explanatory power to the variability in OC stocks over the main environmental variables (VPD, slope) within the Eyre Peninsula cropping soils only. In the wider context, the management data were useful in interpreting differences between regional findings and highlighted difficulties in using uninformed, broad-scale management categories.
EFFECT OF ELECTROLYTE CONCENTRATION ON GLUCOSE DECOMPOSITION IN SOIL
Publisher: CSIRO Publishing
Date: 1989
DOI: 10.1071/SR9890433
Abstract: The influence of the electrolyte concentration of the soil solution on the ability of the soil biomass to decompose glucose was assessed by determining the residual glucose content of soil s les in a laboratory incubation experiment. For three amounts of glucose addition (0, 3.5 and 70 mg glucose g-1 soil), the electrolyte concentration of the soil solution was varied between that of deionized water and a 0.10 M CaCl2 solution. A significant decrease in the rate of glucose decomposition was only noted once the concentration of Ca2+ in the soil solution reached 0.10 M however, after 125 h incubation, the extent Of glucose decomposition was not significantly influenced by changes in Ca2+ concentration. Therefore, increases in the electrolyte concentration of soils amended with gypsum or agricultural lime are not likely to inhibit the activity of the microbial biomass and its ability to decompose organic residues.
Sources and distribution of CuO-derived benzene carboxylic acids in soils and sediments
Publisher: Elsevier BV
Date: 08-2007
Characterisation of aged black carbon using pyrolysis-GC/MS, thermally assisted hydrolysis and methylation (THM), direct and cross-polarisation 13C nuclear magnetic resonance (DP/CP NMR) and the benze
Publisher: Elsevier BV
Date: 10-2008
Catchment scale mapping of measureable soil organic carbon fractions
Publisher: Elsevier BV
Date: 05-2014
Composition and cycling of organic carbon in soils
Publisher: Springer Berlin Heidelberg
Date: 2007
Model organic compounds differ in their effects on pH changes of two soils differing in initial pH
Publisher: Springer Science and Business Media LLC
Date: 18-09-2011
Variability and Vulnerability of Coastal ‘Blue Carbon’ Stocks: A Case Study from Southeast Australia
Publisher: Springer Science and Business Media LLC
Date: 25-04-2017
Predicting soil carbon saturation deficit and related properties of New Zealand soils using infrared spectroscopy
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/SR19149
Abstract: Conversion of soils supporting native vegetation to agricultural production has led to a loss of soil carbon stocks. Replacing a portion of the lost stocks will sequester atmospheric carbon with the concurrent benefit of enhancing soil sustainability. The ability of the fine fraction of soils (≤50-µm fraction) to adsorb organic carbon (OC) is considered a key mechanism capable of stabilising soil OC against loss. The difference between the current and maximum concentrations of OC in the soil fine fraction (FFC) has been termed the ‘saturation deficit’ (SatDef) and used to define the potential for a soil to sequester carbon. For New Zealand surface 0–15 cm soil layers, pedotransfer functions have been derived to quantify the soil carbon SatDef. The ability of combining infrared spectroscopy (IR) with partial least squares regression (PLSR) to derive predictive algorithms for soil properties included in these pedotransfer functions, the capacity of the soil fine fraction to stabilise carbon and the SatDef of the soil fine fraction were assessed in this study. A total of 168 air-dried and finely ground New Zealand surface soils representative of the major soil orders used for agricultural production were included. Principal components analysis of IR spectra showed a grouping by soil order that was related to mineralogy. Predictive IR/PLSR algorithms were derived for specific surface area, pyrophosphate-extractable aluminium, the FFC content, the 90th quantile regression of FFC and the SatDef of the fine fraction (R2 values ≥0.85 ratio of performance to interquartile range values ≥2.9). The results indicate that IR/PLSR provides a rapid and cost-effective mechanism for deriving information related to the amount of FFC in soils and the SatDef of the fine fraction. The IR/PLSR approach could be used to define the potential of soils to sequester carbon and identify the soil types to target for carbon sequestration technologies. The approach would also generate valuable data for soil carbon in national inventories or national soil condition monitoring programs.
An Improved Thermal Oxidation Method for the Quantification of Soot/Graphitic Black Carbon in Sediments and Soils
Publisher: American Chemical Society (ACS)
Date: 07-08-2001
DOI: 10.1021/ES010504C
Abstract: Recent findings have confirmed the importance of black carbon (BC) in the global biogeochemical cycles of carbon and oxygen through its important contribution to the slowly cycling organic carbon (OC) pool. Yet, most BC determination methods published to date measure operationally defined BC fractions, oftentimes with a high potential for artifacts and a lack of specificity for one of the two major forms of the BC continuum, soot/graphitic BC (GBC) and char/charcoal BC (CBC). This paper describes a method that reduces the potential for artifacts to accurately and selectively measure the concentration of GBC in complex mineral and organic matrixes. Marine and lacustrine sediments, river sediments, suspended particles, and a marine plankton s le were first demineralized with a mixture of hydrochloric (HCl) and hydrofluoric (HF) acids to expose any biochemical entrapped in a mineral matrix. The hydrolyzable organic matter fraction (mostly proteins and carbohydrates) was then removed with 02-free trifluoroacetic acid and HCl, after which the non-GBC, non-hydrolyzable OC fraction was finally removed by thermal oxidation at 375 degrees C for 24 h. The specificity of the method for GBC was assessed with pure CBC and GBC s les. Detection limit and GBC recovery in spiked s les were 10 mg kg(-1) and approximately 85%, respectively. Typical GBC concentrations measured in a series of natural s les ranged from <10 mg kg(-1) in marine plankton to 0.19% in a riverine s le. These concentrations were lower by as much as 3 orders of magnitude than those obtained by thermal oxidation without demineralization and removal of hydrolyzable organic matter. The improvements presented in this work allow for the accurate and precise measurement of GBC in complex organic and mineral matrixes by eliminating the interference caused by the presence of CBC, residual non-BC OC and minerals, or by the formation of condensation products that could account for as much as 4-6% of total OC. Combined to stable and radioisotope analysis, this improved method should permit quantitative assessments of the role and dynamics of GBC in the global geochemical cycles of carbon and oxygen.
Assessing the risk of carbon dioxide emissions from blue carbon ecosystems
Publisher: Wiley
Date: 15-05-2017
DOI: 10.1002/FEE.1491
Continental-scale soil carbon composition and vulnerability modulated by regional environmental controls
Publisher: Springer Science and Business Media LLC
Date: 03-06-2019
Reducing nitrous oxide emissions and nitrogen leaching losses from irrigated arable cropping in Australia through optimized irrigation scheduling
Publisher: Elsevier BV
Date: 08-2015
Linking soils and streams: Sources and chemistry of dissolved organic matter in a small coastal watershed
Publisher: American Geophysical Union (AGU)
Date: 03-2009
DOI: 10.1029/2008WR006977
Fixed nitrogen in sustainable farming systems: a symposium examining factors influencing the extent of biological nitrogen fixation and its role in southern Australian agricultural systems. Setting the scene [editorial]
Publisher: Elsevier BV
Date: 08-2004
Climate and Soil Characteristics Determine Where No-Till Management Can Store Carbon in Soils and Mitigate Greenhouse Gas Emissions
Publisher: Springer Science and Business Media LLC
Date: 12-08-2019
DOI: 10.1038/S41598-019-47861-7
Abstract: Adoption of no-till management on croplands has become a controversial approach for storing carbon in soil due to conflicting findings. Yet, no-till is still promoted as a management practice to stabilize the global climate system from additional change due to anthropogenic greenhouse gas emissions, including the 4 per mille initiative promoted through the UN Framework Convention on Climate Change. We evaluated the body of literature surrounding this practice, and found that SOC storage can be higher under no-till management in some soil types and climatic conditions even with redistribution of SOC, and contribute to reducing net greenhouse gas emissions. However, uncertainties tend to be large, which may make this approach less attractive as a contributor to stabilize the climate system compared to other options. Consequently, no-till may be better viewed as a method for reducing soil erosion, adapting to climate change, and ensuring food security, while any increase in SOC storage is a co-benefit for society in terms of reducing greenhouse gas emissions.
Carbon sequestration under subtropical perennial pastures II: Carbon dynamics
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12351
Abstract: Here we take advantage of the stable carbon isotope shift that occurs when a C4 plant is sown into a soil previously dominated by C3 vegetation, to explore the movement and fate of newly sequestered soil organic carbon (SOC) following establishment of subtropical perennial pastures in temperate regions of Australia. In kikuyu-based pastures up to 33 years of age, SOC accumulated exclusively in the coarse size fraction ( μm) in the sandy soils of southern Western Australia. In South Australian loams, regardless of pasture age, new SOC was found to accumulate in both the coarse and fine ( μm) size fractions. These differential results suggest that in soils with low clay content, new SOC remains in an unprotected form that is highly vulnerable to loss through decomposition and erosion. The Rothamsted Carbon Model, modified to track changes in stable isotopes, was able to represent the changes in total SOC stocks in both regions however, the model over-predicted the incorporation of the new C4-SOC into the soil. This difference between data and model output could be reconciled if a greater proportion of new SOC is rapidly mineralised without being incorporated into any sort of stabilised pool.
Biochemical Suitability of Crop Residues for Cellulosic Ethanol: Disincentives to Nitrogen Fertilization in Corn Agriculture
Publisher: American Chemical Society (ACS)
Date: 03-2011
DOI: 10.1021/ES103252S
Abstract: Concerns about energy security and climate change have increased biofuel demand, particularly ethanol produced from cellulosic feedstocks (e.g., food crop residues). A central challenge to cropping for cellulosic ethanol is the potential environmental damage from increased fertilizer use. Previous analyses have assumed that cropping for carbohydrate in residue will require the same amount of fertilizer as cropping for grain. Using (13)C nuclear magnetic resonance, we show that increases in biomass in response to fertilization are not uniform across biochemical classes (carbohydrate, protein, lipid, lignin) or tissues (leaf and stem, grain, reproductive support). Although corn grain responds vigorously and nonlinearly, corn residue shows only modest increases in carbohydrate yields in response to high levels of fertilization (25% increase with 202 kg N ha(-1)). Lignin yields in the residue increased almost twice as much as carbohydrate yields in response to nitrogen, implying that residue feedstock quality declines as more fertilizer is applied. Fertilization also increases the decomposability of corn residue, implying that soil carbon sequestration becomes less efficient with increased fertilizer. Our results suggest that even when corn is grown for grain, benefits of fertilization decline rapidly after the ecosystem's N demands are met. Heavy application of fertilizer yields minimal grain benefits and almost no benefits in residue carbohydrates, while degrading the cellulosic ethanol feedstock quality and soil carbon sequestration capacity.
Microbial utilisation of biochar-derived carbon
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2013.03.090
Abstract: Whilst largely considered an inert material, biochar has been documented to contain a small yet significant fraction of microbially available labile organic carbon (C). Biochar addition to soil has also been reported to alter soil microbial community structure, and to both stimulate and retard the decomposition of native soil organic matter (SOM). We conducted a short-term incubation experiment using two (13)C-labelled biochars produced from wheat or eucalypt shoots, which were incorporated in an aridic arenosol to examine the fate of the labile fraction of biochar-C through the microbial community. This was achieved using compound specific isotopic analysis (CSIA) of phospholipid fatty acids (PLFAs). A proportion of the biologically-available fraction of both biochars was rapidly (within three days) utilised by gram positive bacteria. There was a sharp peak in CO2 evolution shortly after biochar addition, resulting from rapid turnover of labile C components in biochars and through positive priming of native SOM. Our results demonstrate that this CO2 evolution was at least partially microbially mediated, and that biochar application to soil can cause significant and rapid changes in the soil microbial community likely due to addition of labile C and increases in soil pH.
Predictive mapping of soil organic carbon stocks in South Australia’s agricultural zone
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/SR15100
Abstract: Better understanding the spatial distribution of soil organic carbon (SOC) stocks is important for the management and enhancement of soils for production and environmental outcomes. We have applied digital soil mapping (DSM) techniques to combine soil-site datasets from legacy and recent sources, environmental covariates and expert pedological knowledge to predict and map SOC stocks in the top 0.3 m, and their uncertainty, across South Australia’s agricultural zone. In achieving this, we aimed to maximise the use of locally sourced datasets not previously considered in national soil C assessments. Practical considerations for operationalising DSM are also discussed in the context of working with problematic legacy datasets, handling large numbers of potentially correlated covariates, and meeting end-user needs for readily interpretable results and accurate maps. Spatial modelling was undertaken using open-source R statistical software over a study area of ~160 000 km2. Legacy-site SOC stock estimates were derived with inputs from an expert-derived bulk-density pedotransfer function to overcome critical gaps in the data. Site estimates of SOC were evaluated over a consistent depth range and then used in spatial predictions through an environmental-correlation regression-kriging DSM approach. This used the contemporary Least Absolute Shrinkage and Selection Operator penalised-regression method, which catered for a large number (63 numeric, four categorical, four legacy-soil mapping themes) of potentially correlated covariates. For efficient use of the available data, this was performed within a k-fold cross-validation (k = 10) modelling framework. Through this, we generated multiple predictions and variance information at every node of our prediction grid, which was used to evaluate and map the expected value (mean) of SOC stocks and their uncertainty. For the South Australian agricultural zone, expected value SOC stocks in the top 0.3 m summed to 0.589 Gt with a 90% prediction interval of 0.266–1.086 Gt.
Solid-state CP/MAS 13C N.M.R. analysis of bacterial and fungal cultures isolated from a soil incubated with glucose
Publisher: CSIRO Publishing
Date: 1990
DOI: 10.1071/SR9900213
Abstract: Bacteria and fungi were isolated from a s le of the Meadows fine sandy loam, an Alfisol, and selectively cultured in nutrient solutions at 20�C for 5 days. The bacteria and fungi were collected, washed with deionized water, freeze dried and analysed using conventional and dipolar dephased solid state CP/MAS 13C n.m.r. spectroscopy. To obtain a quantitative estimate of the chemical composition of the bacterial and fungal carbon, a recycle delay of 3.0 s was required to allow complete relaxation between pulses, and the acquired signal intensities had to be corrected for the amount of signal relaxation which occurred during the contact time (i.e. T1pH effects). The bacterial materials contained more alkyl and carboxyl carbon but less O-alkyl and acetal carbon than the fungal materials. Comparison of the composition of the bacterial and fungal carbon with that of the native and residual substrate carbon contained in the clay and light fraction of a s le of Meadows fine sandy loam incubated with 13C-glucose indicated that the soil microbial population was dominated by fungi.
Influence of size of rainfall events on water-driven processes II. Soil Nitrogen mineralisation in a semi-arid environment
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/AR02113
Abstract: Power laws describe the relationships between the number N (s) and the size s of daily rainfall events, i.e. N (s) ~ s–τ, with higher τ corresponding to sites or seasons with greater frequency of small rainfall events. This paper tested the hypothesis that the rate of soil nitrogen mineralisation increases with increasing exponent τ, as affected by both spatial and temporal sources of variation. Rates of nitrogen mineralisation in an uncropped sandy loam soil were calculated using a simulation model with detailed nitrogen and water balances, and long-term weather data for 6 Australian locations in a range of annual rainfall from 260 to 360 mm. Daily rates of mineralisation were calculated using actual rainfall, and variable or fixed temperature and evaporative demand. The annual pattern of mineralisation rate, calculated as a function of rainfall and variable temperature and evaporative demand, was bimodal with peaks in April and November. These peaks disappeared and differences among locations were reduced when the effects of temperature and evaporative demand were removed. Under constant temperature and evaporative demand, mineralisation rates between April and November were 68% greater than rates between December and March. In the former period, characterised by a high frequency of small rainfall events, monthly mineralisation rate was a direct function of the amount of rainfall. In contrast, mineralisation was independent of the amount of rainfall during the period of larger, less frequent rainfall events from December to March. Parameter τ accounted for 75% of the variation in mineralisation rate in the period December–March and it also accounted for a substantial part of the variation between periods.
Technical assessment of the Verified Carbon Standard – “VM033 Methodology for Tidal Wetland and Seagrass Restoration
Publisher: CSIRO
Date: 2019
Optimal soil carbon sampling designs to achieve cost-effectiveness: a case study in blue carbon ecosystems
Publisher: The Royal Society
Date: 09-2018
Abstract: Researchers are increasingly studying carbon (C) storage by natural ecosystems for climate mitigation, including coastal ‘blue carbon’ ecosystems. Unfortunately, little guidance on how to achieve robust, cost-effective estimates of blue C stocks to inform inventories exists. We use existing data (492 cores) to develop recommendations on the s ling effort required to achieve robust estimates of blue C. Using a broad-scale, spatially explicit dataset from Victoria, Australia, we applied multiple spatial methods to provide guidelines for reducing variability in estimates of soil C stocks over large areas. With a separate dataset collected across Australia, we evaluated how many s les are needed to capture variability within soil cores and the best methods for extrapolating C to 1 m soil depth. We found that 40 core s les are optimal for capturing C variance across 1000's of kilometres but higher density s ling is required across finer scales (100–200 km). Accounting for environmental variation can further decrease required s ling. The within core analyses showed that nine s les within a core capture the majority of the variability and log-linear equations can accurately extrapolate C. These recommendations can help develop standardized methods for s ling programmes to quantify soil C stocks at national scales.
INCORPORATION OF UNIFORMLY LABELED C-13-GLUCOSE CARBON INTO THE ORGANIC FRACTION OF A SOIL - CARBON BALANCE AND CP MAS C-13 NMR MEASUREMENTS
Publisher: CSIRO Publishing
Date: 1989
DOI: 10.1071/SR9890725
Abstract: The incorporation of uniformly labelled 13C-giucose into soil organic matter was followed using mass spectrometry to make carbon balance measurements, and using solid state CP/MAS 13C NMR (cross polarization/magic angle spinning 13C nuclear magnetic resonance) spectroscopy to determine changes in the chemical structure of the added 13C with time. A fine sandy loam soil was incubated in the presence and absence of the labelled 13C-glucose for up to 34 days at 22�C and a soil water matric potential of -33 kPa. Carbon balance measurements indicated that no priming effect of glucose addition on decomposition of the native organic carbon occurred, and that 65% of the glucose 13C was mineralized during the incubation period. The ability of solid-state CP/MAS 13C NMR to quantitatively detect all of the substrate 13C present in the s les was assessed by comparing the residual substrate 13C contents of the s les analysed with the corresponding CP/MAS 13C NMR signal intensities. Incorporation of the glucose 13C into the soil organic matter resulted in the synthesis of alkyl (26%), O-alkyl (66%), and carboxyl (8%) carbon, but little if any aromatic carbon. The influence of decomposition processes on the chemical characteristics of the soil organic matter is discussed, and the chemical structure of the materials synthesized by the microbial biomass is compared with that of the native soil organic matter.
Effect of soil texture and wheat plants on N2 O fluxes: A lysimeter study
Publisher: Elsevier BV
Date: 06-2016
The effects of vegetation and burning on the chemical composition of soil organic matter in a volcanic ash soil as shown by C-13 NMR spectroscopy .1. Whole soil and humic acid fraction
Publisher: Elsevier BV
Date: 04-1997
Crop rotation effect on wheat grain yield as mediated by changes in the degree of water and nitrogen co-limitation
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/AR04012
Abstract: Theoretically, growth of stressed plants is maximised when all resources are equally limiting. The concept of co-limitation could be used to integrate key factors affected by crop rotation. This paper tested the hypothesis that the effect of crop rotation on the yield of wheat is partially mediated by changes in the degree of co-limitation between nitrogen and water. Four rotations were established on a sodic, supracalcic, red chromosol in a Mediterranean-type environment of southern Australia. Rotations included wheat grown after (a) faba bean harvested for grain, (b) faba bean incorporated as green manure, (c) ryegrass pasture, or (d) medic pasture barley was grown after wheat in all cases. The response of wheat to the rotations during 3 growing seasons was analysed in terms of nitrogen and water co-limitation, and the response of barley was taken as a measure of the persistence of rotation effects. Daily scalars quantifying water and nitrogen stress effects on tissue expansion were calculated with a crop simulation model. These scalars were integrated in a series of seasonal indices to quantify the intensity of water (SW ) and nitrogen stress (SN ), the aggregated intensity of water and nitrogen stress (SWN ), the degree of water and nitrogen co-limitation (CWN ), and the integrated effect of stress and co-limitation (SCWN 25 CWN/SWN ). The expectation is that grain yield should be inversely proportional to stress intensity and directly proportional to degree of co-limitation, thus proportional to SCWN . Combination of rotations and seasons generated a wide variation in the amount of water and inorganic nitrogen in the 1-m soil profile at the time of wheat sowing. Plant-available water ranged from 33 to 107 mm, and inorganic nitrogen from 47 to 253 kg N/ha. Larger amounts of nitrogen were found after green-manured faba bean, and smaller after grass pasture. There was a consistent effect of rotation on wheat yield and grain protein content, which persisted in subsequent barley crops. Measured grain yield of wheat crops ranged from 2.5 to 4.8 t/ha. It was unrelated to water or nitrogen stresses taken in idually, inversely related to the aggregated stress index SWN , and directly related to the CWN index of co-limitation. The combination of stress and co-limitation in a single index SCWN accounted for 65% of the variation in measured crop yield. This is a substantial improvement with respect to the stress effect quantified with SWN , which accounted for 43% of yield variation. It is concluded that rotation effects mediated by changes in the relative availability of water and nitrogen can be partially accounted for by degree of resource co-limitation.
Concepts in modelling N2O emissions from land use
Publisher: Springer Science and Business Media LLC
Date: 12-12-2007
Baseline map of Australian soil organic carbon stocks and their uncertainty
Publisher: No publisher found
Date: 2015
Evidence for non-selective preservation of organic matter in sinking marine particles
Publisher: Springer Science and Business Media LLC
Date: 15-02-2001
DOI: 10.1038/35057247
Abstract: The sinking of particulate organic matter from ocean surface waters transports carbon to the ocean interior, where almost all is then recycled. The unrecycled fraction of this organic matter can become buried in ocean sediments, thus sequestering carbon and so influencing atmospheric carbon dioxide concentrations. The processes controlling the extensive biodegradation of sinking particles remain unclear, partly because of the difficulty in resolving the composition of the residual organic matter at depth with existing chromatographic techniques. Here, using solid-state 13C NMR spectroscopy, we characterize the chemical structure of organic carbon in both surface plankton and sinking particulate matter from the Pacific Ocean and the Arabian Sea. We found that minimal changes occur in bulk organic composition, despite extensive (>98%) biodegradation, and that amino-acid-like material predominates throughout the water column in both regions. The compositional similarity between phytoplankton biomass and the small remnant of organic matter reaching the ocean interior indicates that the formation of unusual biochemicals, either by chemical recombination or microbial biosynthesis, is not the main process controlling the preservation of particulate organic carbon within the water column at these two sites. We suggest instead that organic matter might be protected from degradation by the inorganic matrix of sinking particles.
Modeling soil carbon and nitrogen dynamics using measurable and conceptual soil organic matter pools in APSIM
Publisher: Elsevier BV
Date: 03-2014
Potential soil organic carbon stock and its uncertainty under various cropping systems in Australian cropland
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/SR13294
Abstract: The ersity of cropping systems and its variation could lead to great uncertainty in the estimation of soil organic carbon (SOC) stock across time and space. Using the pre-validated Agricultural Production Systems Simulator, we simulated the long-term (1022 years) SOC dynamics in the top 0.3 m of soil at 613 reference sites under 59 representative cropping systems across Australia’s cereal-growing regions. The point simulation results were upscaled to the entire cereal-growing region using a Monte Carlo approach to quantify the spatial pattern of SOC stock and its uncertainty caused by cropping system and environment. The predicted potential SOC stocks at equilibrium state ranged from 10 to 140 t ha–1, with the majority in a range 30–70 t ha–1, averaged across all the representative cropping systems. Cropping system accounted for ~10% of the total variance in predicted SOC stocks. The type of cropping system that determined the carbon input into soil had significant effects on SOC sequestration potential. On average, the potential SOC stock in the top 0.3 m of soil was 30, 50 and 60 t ha–1 under low-, medium- and high-input cropping systems in terms of carbon input, corresponding to –2, 18 and 26 t ha–1 of SOC change. Across the entire region, the Monte Carlo simulations showed that the potential SOC stock was 51 t ha–1, with a 95% confidence interval ranging from 38 to 64 t ha–1 under the identified representative cropping systems. Overall, predicted SOC stock could increase by 0.99 Pg in Australian cropland under the identified representative cropping systems with optimal management. Uncertainty varied depending on cropping system, climate and soil conditions. Detailed information on cropping system and soil and climate characteristics is needed to obtain reliable estimates of potential SOC stock at regional scale, particularly in cooler and/or wetter regions.
Carbon stocks, sequestration, and emissions of wetlands in south eastern Australia
Publisher: Wiley
Date: 24-06-2018
DOI: 10.1111/GCB.14319
Abstract: Nontidal wetlands are estimated to contribute significantly to the soil carbon pool across the globe. However, our understanding of the occurrence and variability of carbon storage between wetland types and across regions represents a major impediment to the ability of nations to include wetlands in greenhouse gas inventories and carbon offset initiatives. We performed a large-scale survey of nontidal wetland soil carbon stocks and accretion rates from the state of Victoria in south-eastern Australia-a region spanning 237,000 km
Is CO2 evolution in saline soils affected by an osmotic effect and calcium carbonate?
Publisher: Springer Science and Business Media LLC
Date: 15-07-2010
The sorption of organic carbon onto differing clay minerals in the presence and absence of hydrous iron oxide
Publisher: Elsevier BV
Date: 11-2013
Importance of mechanisms and processes of the stabilization of soil organic matter for modelling carbon turnover
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/FP02085
Abstract: This paper reviews current knowledge of soil organic carbon (SOC) dynamics with respect to physical protection, soil moisture and temperature, and recalcitrant carbon fractions (such as charcoal) in predominantly agricultural soils. These factors are discussed within the framework of current soil organic matter models. The importance of soil structure in the stabilisation of organic residues through physical protection has been documented previously in various studies. In addition, changes in soil structure associated with tillage can significantly affect soil organic matter decomposition rates. The concept of physical protection has been incorporated into several soil carbon models as a function of soil texture. While soil texture can affect the soil's capacity for aggregation and adsorption, factors such as soil moisture and temperature may further enhance or reduce the extent of physical protection. While adsorption and aggregation can slow decomposition processes, it is unlikely that these processes are solely responsible for the high mean residence times measured in biologically active surface soils. Accordingly, chemical recalcitrance appears to be the only mechanism by which soil organic carbon can be protected for long periods of time.
Electrospray and photoionization mass spectrometry for the characterization of organic matter in natural waters: a qualitative assessment
Publisher: Wiley
Date: 2009
Soil biological properties following additions of bmr mutant grain sorghum
Publisher: Elsevier BV
Date: 07-2007
Rhizosphere priming effect on soil organic carbon decomposition under plant species differing in soil acidification and root exudation
Publisher: Wiley
Date: 22-04-2016
DOI: 10.1111/NPH.13966
Abstract: Effects of rhizosphere properties on the rhizosphere priming effect ( RPE ) are unknown. This study aimed to link species variation in RPE with plant traits and rhizosphere properties. Four C 3 species (chickpea, Cicer arietinum field pea, Pisum sativum wheat, Triticum aestivum and white lupin, Lupinus albus ) differing in soil acidification and root exudation, were grown in a C 4 soil. The CO 2 released from soil was trapped using a newly developed Na OH ‐trapping system. White lupin and wheat showed greater positive RPE s, in contrast to the negative RPE produced by chickpea. The greatest RPE of white lupin was in line with its capacity to release root exudates, whereas the negative RPE of chickpea was attributed to its great ability to acidify rhizosphere soil. The enhanced RPE of field pea at maturity might result from high nitrogen deposition and release of structural root carbon components following root senescence. Root biomass and length played a minor role in the species variation in RPE . Rhizosphere acidification was shown to be an important factor affecting the magnitude and direction of RPE . Future studies on RPE modelling and mechanistic understanding of the processes that regulate RPE should consider the effect of rhizosphere pH .
Forest soil carbon oxidation state and oxidative ratio responses to elevated CO2
Publisher: American Geophysical Union (AGU)
Date: 09-2015
DOI: 10.1002/2015JG003010
Abstract: The oxidative ratio (OR) of the biosphere is the stoichiometric ratio (O 2 /CO 2 ) of gas exchange by photosynthesis and respiration—a key parameter in budgeting calculations of the land and ocean carbon sinks. Carbon cycle‐climate feedbacks could alter the OR of the biosphere by affecting the quantity and quality of organic matter in plant biomass and soil carbon pools. This study considers the effect of elevated atmospheric carbon dioxide concentrations ([CO 2 ]) on the OR of a hardwood forest after nine growing seasons of Free‐Air CO 2 Enrichment. We measured changes in the carbon oxidation state (C ox ) of biomass and soil carbon pools as a proxy for the ecosystem OR. The OR of net primary production, 1.039, was not affected by elevated [CO 2 ]. However, the C ox of the soil carbon pool was 40% higher at elevated [CO 2 ], and the estimated OR values for soil respiration increased from 1.006 at ambient [CO 2 ] to 1.054 at elevated [CO 2 ]. A biochemical inventory of the soil organic matter ascribed the increases in C ox and OR to faster turnover of reduced substrates, lignin and lipids, at elevated [CO 2 ]. This implicates the heterotrophic soil community response to elevated [CO 2 ] as a driver of disequilibrium in the ecosystem OR. The oxidation of soil carbon pool constitutes an unexpected terrestrial O 2 sink. Carbon budgets constructed under the assumption of OR equilibrium would equate such a terrestrial O 2 sink to CO 2 uptake by the ocean. The potential for climate‐driven disequilibriua in the cycling of O 2 and CO 2 warrants further investigation.
The effect of landuse on soil organic carbon chemistry and sorption of pesticides and metabolites
Publisher: Elsevier BV
Date: 07-2005
DOI: 10.1016/J.CHEMOSPHERE.2005.01.027
Abstract: Earlier studies had shown significant differences in sorption of nine pesticides in soils collected from two landuses (native vegetation and market gardens), which could not be explained on the basis of organic carbon content alone. Consequently it was hypothesised that the differences in sorption behaviour between the two landuses may be due to variation in the chemistry of the organic carbon. In this study the relationship between sorption behaviour of the nine chemicals and soil organic carbon chemistry, as determined by solid-state (13)C NMR spectroscopy, was investigated. No significant differences were found between the two landuses in the distribution of the four main spectral regions of the (13)C NMR spectra of soil OC, except for the carbonyl fraction (165-220ppm), which may reflect the low OC content of the soils from both landuses. For all chemicals, except prometryne, the most significant (P<0.01 or P<0.001) relationship between K(d) values and types of OC was found with the aromatic (110-165ppm) or the alkyl (0-45ppm) fraction. A comparison was made of the variability of K(d) values normalized over OC (i.e. K(oc)), alkyl, aromatic and alkyl+aromatic fractions. Expressing K(d) values for all chemicals, except azinphos methyl, in soils under native vegetation as K(alkyl) or K(aromatic) greatly decreased the variability compared with the K(oc) value. However in the cultivated soils only the sorption coefficients for DEA, DIA and fenamiphos showed a decrease in variability when expressed as K(alkyl) or K(aromatic). This reflected the stronger relationship between sorption coefficients and the alkyl and aromatic fraction of soil OC in soils from native vegetation compared with those determined from the market garden soils. The different relationships between sorption coefficients and types of OC of the two landuses also suggests that the type of aromatic and alkyl carbon under the two landuses is different and NMR characterisation of the OC was not sufficient to distinguish these differences.
Sediment anoxia limits microbial-driven seagrass carbon remineralization under warming conditions
Publisher: Oxford University Press (OUP)
Date: 15-03-2017
Abstract: Seagrass ecosystems are significant carbon sinks, and their resident microbial communities ultimately determine the quantity and quality of carbon sequestered. However, environmental perturbations have been predicted to affect microbial-driven seagrass decomposition and subsequent carbon sequestration. Utilizing techniques including 16S-rDNA sequencing, solid-state NMR and microsensor profiling, we tested the hypothesis that elevated seawater temperatures and eutrophication enhance the microbial decomposition of seagrass leaf detritus and rhizome/root tissues. Nutrient additions had a negligible effect on seagrass decomposition, indicating an absence of nutrient limitation. Elevated temperatures caused a 19% higher biomass loss for aerobically decaying leaf detritus, coinciding with changes in bacterial community structure and enhanced lignocellulose degradation. Although, community shifts and lignocellulose degradation were also observed for rhizome/root decomposition, anaerobic decay was unaffected by temperature. These observations suggest that oxygen availability constrains the stimulatory effects of temperature increases on bacterial carbon remineralization, possibly through differential temperature effects on bacterial functional groups, including putative aerobic heterotrophs (e.g. Erythrobacteraceae, Hyphomicrobiaceae) and sulfate reducers (e.g. Desulfobacteraceae). Consequently, under elevated seawater temperatures, carbon accumulation rates may diminish due to higher remineralization rates at the sediment surface. Nonetheless, the anoxic conditions ubiquitous to seagrass sediments can provide a degree of carbon protection under warming seawater temperatures.
Is demineralization with dilute hydrofluoric acid a viable method for isolating mineral stabilized soil organic matter?
Publisher: Elsevier BV
Date: 10-2017
Carbon sequestration by Australian tidal marshes
Publisher: Springer Science and Business Media LLC
Date: 10-03-2017
DOI: 10.1038/SREP44071
Abstract: Australia’s tidal marshes have suffered significant losses but their recently recognised importance in CO 2 sequestration is creating opportunities for their protection and restoration. We compiled all available data on soil organic carbon (OC) storage in Australia’s tidal marshes (323 cores). OC stocks in the surface 1 m averaged 165.41 (SE 6.96) Mg OC ha −1 (range 14–963 Mg OC ha −1 ). The mean OC accumulation rate was 0.55 ± 0.02 Mg OC ha −1 yr −1 . Geomorphology was the most important predictor of OC stocks, with fluvial sites having twice the stock of OC as seaward sites. Australia’s 1.4 million hectares of tidal marshes contain an estimated 212 million tonnes of OC in the surface 1 m, with a potential CO 2 -equivalent value of $USD7.19 billion. Annual sequestration is 0.75 Tg OC yr −1 , with a CO 2 -equivalent value of $USD28.02 million per annum. This study provides the most comprehensive estimates of tidal marsh blue carbon in Australia, and illustrates their importance in climate change mitigation and adaptation, acting as CO 2 sinks and buffering the impacts of rising sea level. We outline potential further development of carbon offset schemes to restore the sequestration capacity and other ecosystem services provided by Australia tidal marshes.
Changes in dispersible clay content, organic carbon content, and electrolyte composition following incubation of sodic soil
Publisher: CSIRO Publishing
Date: 1998
DOI: 10.1071/S98024
Abstract: Measurement of dispersible clay is important for the diagnosis of structural stability problems in soil. However, clay dispersibility is known to change with water content and time. The purpose of the present study was to determine how incubation of sodic soil under different water content regimes influences clay dispersibility. Two topsoils (depth 0-0·1 m), one sodic [exchangeable sodium percentage (ESP) 9 · 7] and the other non-sodic (ESP 3·8), were collected from an experimental pasture at Kyabram, Victoria, and 2 soils, a sodic topsoil (depth 0-0·1 m, ESP 6·9) and the corresponding subsoil (depth 0·2-0 m, ESP 25·7), were collected from a cropped field at Two Wells, South Australia. The soils were incubated for 264 days in a split-plot design. The main treatments were soil type and incubation water content: continuously air-dry, continuously wet (-50 kPa), or with wet/dry cycles. The subtreatment was water content at analysis: air dry or wet (-50 kPa). Clay dispersion was greater when measured on wet soils than dry soils, irrespective of water contents during the prior incubation. Electrical conductivity increased, and sodium adsorption ratio (SAR), pH, and organic carbon content decreased as a function of the time for which the soils were wet. In the Kyabram soils that were wet when analysed, easily dispersible clay content increased with SAR. Decreases in moderately dispersible clay under the wetting/drying regime were not related to electrolyte composition, and were attributed to particle rearrangement and cementation. The decreases in clay dispersibility with time occurred despite net losses of carbohydrate and aliphatic materials. An implication of the work is that the decomposition of soil organic matter, even in the absence of fresh additions, may reduce clay dispersion in sodic soils by altering electrolyte concentration and composition.
Building a foundation for soil condition assessment
Publisher: CSIRO Land and Water
Date: 2009
Influence of chlorsulfuron on rhizobial growth, nodule formation, and nitrogen fixation with chickpea
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/AR03057
Abstract: Sulfonylurea residues have been found to inhibit the growth of some legume crops and pastures in seasons following application. Negative effects of these herbicides on symbiotic nitrogen fixation by legume crops and pastures have been demonstrated. Reductions in nitrogen fixation may result from a direct effect of the herbicide on rhizobial growth and/or an indirect effect on plant growth. In this study the influence of chlorsulfuron on the growth of chickpea rhizobia [Mesorhizobium ciceri (CC1192)], the growth of chickpea plants, and the extent of nodulation and nitrogen fixation by the chickpea/rhizobia symbiosis were examined. In vitro studies (in yeast mannitol broth and a defined medium) showed that chlorsulfuron applied at double the recommended field application rate did not influence the growth of chickpea rhizobia. An experiment using 14C-labelled chlorsulfuron was conducted to determine if rhizobial cells exposed to chlorsulfuron could deliver the herbicide to the point of root infection and nodule formation. Approximately 1% of the herbicide present in the rhizobial growth medium remained with the cell/inoculum material after rinsing with 1/4 strength Ringer’s solution. This was considered unlikely to affect chickpea growth, nodulation, or nitrogen fixation. A pot experiment was used to define the influence of chlorsulfuron on the growth, nodulation, and nitrogen fixation of chickpeas. The presence of chlorsulfuron in the soil reduced the nodulation and nitrogen fixation of the chickpea plants. Pre-exposing rhizobia to chlorsulfuron before inoculating them into pots with germinating chickpea seeds, reduced the number of nodules formed by 51%. Exposure of chickpeas and chickpea rhizobia to chlorsulfuron can adversely affect the formation and activity of symbiotic nitrogen-fixing nodules, even when only the rhizobial inoculant is exposed briefly to the herbicide.
Cycling and composition of organic matter in terrestrial and marine ecosystems
Publisher: Elsevier BV
Date: 12-2004
Soil organic carbon contributes to alkalinity priming induced by added organic substrates
Publisher: Elsevier BV
Date: 10-2013
The contribution of crop residues to changes in soil pH under field conditions
Publisher: Springer Science and Business Media LLC
Date: 26-08-2013
Salinity effects on carbon mineralization in soils of varying texture
Publisher: Elsevier BV
Date: 09-2011
Environmental and human influences on organic carbon fractions down the soil profile
Publisher: Elsevier BV
Date: 05-2016
Wind erosion reduces soil organic carbon sequestration falsely indicating ineffective management practices
Publisher: Elsevier BV
Date: 09-2016
Convergent modelling of past soil organic carbon stocks but divergent projections
Publisher: Copernicus GmbH
Date: 28-07-2015
Abstract: Abstract. Soil carbon (C) models are important tools for understanding soil C balance and projecting C stocks in terrestrial ecosystems, particularly under global change. The initialization and/or parameterization of soil C models can vary among studies even when the same model and data set are used, causing potential uncertainties in projections. Although a few studies have assessed such uncertainties, it is yet unclear what these uncertainties are correlated with and how they change across varying environmental and management conditions. Here, applying a process-based biogeochemical model to 90 in idual field experiments (ranging from 5 to 82 years of experimental duration) across the Australian cereal-growing regions, we demonstrated that well-designed optimization procedures enabled the model to accurately simulate changes in measured C stocks, but did not guarantee convergent forward projections (100 years). Major causes of the projection uncertainty were due to insufficient understanding of how microbial processes and soil C pool change to modulate C turnover. For a given site, the uncertainty significantly increased with the magnitude of future C input and years of the projection. Across sites, the uncertainty correlated positively with temperature but negatively with rainfall. On average, a 331 % uncertainty in projected C sequestration ability can be inferred in Australian agricultural soils. This uncertainty would increase further if projections were made for future warming and drying conditions. Future improvement in soil C modelling should focus on how the microbial community and its C use efficiency change in response to environmental changes, and better conceptualization of heterogeneous soil C pools and the C transformation among those pools.
Linking decomposition rates of soil organic amendments to their chemical composition
Publisher: CSIRO Publishing
Date: 11-02-2021
DOI: 10.1071/SR20269
Abstract: The stock of organic carbon contained within a soil represents the balance between inputs and losses. Inputs are defined by the ability of vegetation to capture and retain carbon dioxide, effects that management practices have on the proportion of captured carbon that is added to soil and the application organic amendments. The proportion of organic amendment carbon retained is defined by its rate of mineralisation. In this study, the rate of carbon mineralisation from 85 different potential soil organic amendments (composts, manures, plant residues and biosolids) was quantified under controlled environmental conditions over a 547 day incubation period. The composition of each organic amendment was quantified using nuclear magnetic resonance and mid- and near-infrared spectroscopies. Cumulative mineralisation of organic carbon from the amendments was fitted to a two-pool exponential model. Multivariate chemometric algorithms were derived to allow the size of the fast and slow cycling pools of carbon to be predicted from the acquired spectroscopic data. However, the fast and slow decomposition rate constants could not be predicted suggesting that prediction of the residence time of organic amendment carbon in soil would likely require additional information related to soil type, environmental conditions, and management practices in use at the site of application.
Soil organic carbon in cropping and pasture systems of Victoria, Australia
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/SR15008
Abstract: Increasing soil organic carbon (SOC) storage in agricultural soils through changes to management may help to mitigate rising greenhouse gas emissions and sustain agricultural productivity and environmental conditions. However, in order to improve assessment of the potential for increasing SOC storage in the agricultural lands of Victoria, Australia, further information is required on current SOC levels and how they are related to environmental conditions, soil properties and agricultural management. Therefore, we measured stocks of SOC at 615 sites in pasture and cropping systems in Victoria, encompassing eight regions, five soil orders and four management classes (continuous cropping, crop–pasture rotation, sheep or beef pasture, and dairy pasture), and explored relationships between the C stocks and environment, soil and management. The results showed an extremely wide range in SOC, from 2 to 239 t C/ha (0–30 cm). Most of this variation was attributable to climate almost 80% of the variation in SOC stock was related to annual rainfall or vapour pressure deficit (i.e. humidity). Texture-related soil properties accounted for a small, additional amount of variation in SOC. After accounting for climate, differences in SOC between management classes were small and often not significant. Management practices such as stubble retention, minimum cultivation, perennial pasture species, rotational grazing and fertiliser inputs were not significantly related to SOC stock. The relationships between SOC and environment, soil and management were scale-dependent. Within in idual regions, the apparent influence of climate and soil properties on SOC stock varied, and in some regions, much of the variation in SOC stock remained unexplained. The results suggest that, across Victoria, there is a general hierarchy of influence on SOC stock: climate soil properties management class management practices.
Carbon isotope fractionation in the mangrove Avicennia marina has implications for food web and blue carbon research
Publisher: Elsevier BV
Date: 05-2018
Converting beach-cast seagrass wrack into biochar: A climate-friendly solution to a coastal problem
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.09.021
Abstract: Excessive accumulation of plant 'wrack' on beaches as a result of coastal development and beach modification (e.g. groin installation) is a global problem. This study investigated the potential for converting beach-cast seagrass wrack into biochar as a 'climate-friendly' disposal option for resource managers. Wrack s les from 11 seagrass species around Australia were initially screened for their biochar potential using pyrolysis techniques, and then two species - Posidonia australis and Zostera muelleri - underwent detailed analyses. Both species had high levels of refractory materials and high conversion efficiency (48-57%) of plant carbon into biochar carbon, which is comparable to high-quality terrestrial biochar products. P. australis wrack gave higher biochar yields than Z. muelleri consistent with its higher initial carbon content. According to
Allocation into soil organic matter fractions of 14C captured via photosynthesis by two perennial grass pastures
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12375
Abstract: Perennial grass pastures are being increasingly adopted, but little is known about the flows of carbon (C) from photosynthesis into soil organic matter (SOM) that could be used for calculations in carbon accounting. Repeat-pulse labelling of perennial grass pastures (kikuyu and Rhodes grass) with 14C in the field in Western Australia was used to trace the allocation of C to SOM fractions and to determine the stability of each fraction over an extended period. For kikuyu, % of the 14C fed to the plants was allocated belowground within 10 days of labelling, and after 1 year half of this remained. Allocation of 14C belowground under Rhodes grass ranged between 20 and 24% of 14C applied and remained constant for up to 6 months. At least 90% of the 14C belowground was found in the surface 300 mm of soil. The allocation of 14C to the coarse (50 µm–2 mm) and fine ( µm) SOM fractions was similar in magnitude for the two grasses and remained stable through time. It was estimated that in 1 year ~1 t C ha–1 was assimilated into the coarse + fine SOM fractions under kikuyu. However, Rhodes grass was not uniformly distributed across the paddock, thereby reducing the estimates of assimilation of C belowground in these systems to one-tenth of that under kikuyu. Data obtained will help validate plant–soil models for assessing rates of C sequestration under perennial pastures.
A national approach to greenhouse gas abatement through blue carbon management
Publisher: Elsevier BV
Date: 07-2020
Quantifying the allocation of soil organic carbon to biologically significant fractions
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12374
Abstract: Soil organic carbon (OC) exists as a erse mixture of organic materials with different susceptibilities to biological decomposition. Computer simulation models constructed to predict the dynamics of soil OC have dealt with this ersity using a series of conceptual pools differentiated from one another by the magnitude of their respective decomposition rate constants. Research has now shown that the conceptual pools can be replaced by measureable fractions of soil OC separated on the basis of physical and chemical properties. In this study, an automated protocol for allocating soil OC to coarse ( µm) and fine (≤50 µm) fractions was assessed. Automating the size fractionation process was shown to reduce operator dependence and variability between replicate analyses. Solid-state 13C nuclear magnetic resonance spectroscopy was used to quantify the content of biologically resistant poly-aryl carbon in the coarse and fine size fractions. Cross-polarisation analyses were completed for coarse and fine fractions of 312 soils, and direct polarisation analyses were completed for 38 representative fractions. Direct polarisation analyses indicated that the resistant poly-aryl carbon was under-represented in the cross-polarisation analyses, on average, by a factor of ~2. Combining this under-representation with a spectral analysis process allowed the proportion of coarse- and fine-fraction OC existing as resistant poly-aryl C to be defined. The content of resistant OC was calculated as the sum of that found in the coarse and fine fractions. Contents of particulate and humus OC were calculated after subtracting the resistant OC from the coarse and fine fractions, respectively. Across the 312 soils analysed, substantial variations in the contents of humus, particulate, and resistant carbon were noted, with respective average values of 9.4, 4.0, and 4.5 g fraction C/kg soil obtained. When expressed as a proportion of the OC present in each soil, the humus, particulate, and resistant OC accounted for 56, 19, and 26%, respectively. The nuclear magnetic resonance analyses also indicated that the use of a 50-µm sieve to differentiate particulate ( µm) from humus (≤50 µm) forms of OC provided an effective separation based on extents of decomposition. The procedures developed in this study provided a means to differentiate three biologically significant forms of soil OC based on size, extent of decomposition, and chemical composition (poly-aryl content).
Carbon pulses but not phosphorus pulses are related to decreases in microbial biomass during repeated drying and rewetting of soils
Publisher: Elsevier BV
Date: 07-2009
SOIL AGGREGATION AND CROPPING SYSTEMS
Publisher: Elsevier BV
Date: 11-1986
Erratum to: Concepts in modelling N2O emissions from land use
Publisher: Springer Science and Business Media LLC
Date: 12-09-2009
Estimating the molecular composition of a diverse range of natural organic materials from solid-state 13C NMR and elemental analyses
Publisher: Springer Science and Business Media LLC
Date: 2005
Nitrogen dynamics of pastures: nitrogen fixation inputs, the impact of legumes on soil nitrogen fertility, and the contributions of fixed nitrogen to Australian farming systems
Publisher: CSIRO Publishing
Date: 2001
DOI: 10.1071/EA99139
Abstract: Experimental estimates of amounts of foliage nitrogen (N) fixed in Australian pastures range from 2 to 284 kg N/ha.year for annual and perennial legumes growing in temperate and tropical environments. Differences in the amounts of N2 fixed relate primarily to the legume content and net productivity of pastures. On average, close to 20–25 kg of shoot N are fixed for every tonne of legume herbage dry matter produced across a wide range of environments. Strategies likely to improve the potential for N2 fixation include: (i) rhizobial inoculation at time of first sowing a new legume species (ii) amelioration of nutritional problems (applications of superphosphate or lime) (iii) manipulation of pasture composition (herbicide applications to remove grasses in annual pastures in the year prior to cropping) and (iv) including lucerne to offset the year-to-year variability in N2 fixation inputs from annual legumes. However, pasture response to such management treatments and the subsequent availability of soil mineral N may be modified by livestock effects on nutrient cycling, pasture productivity and botanical composition. Conclusions about the relative size of the contributions of fixed N to the N economies of Australian farming systems depend on whether or not estimates of fixed N are included for nodulated roots. Thus residual net inputs of fixed N after each year of a legume-based pasture are generally rated sufficient to balance the N removed by at least 1 subsequent wheat crop provided estimates of below-ground N are included in calculations. Pasture type influences the duration of subsequent rotational benefits and while residual effects on mineral N are commonly exhausted within 2 years after an annual legume-based pasture phase, N carry-over following lucerne generally lasts considerably longer.
Role of the soil matrix and minerals in protecting natural organic materials against biological attack
Publisher: Elsevier BV
Date: 07-2000
Long-term effect of lime application on the chemical composition of soil organic carbon in acid soils varying in texture and liming history
Publisher: Springer Science and Business Media LLC
Date: 07-11-2016
Climate and soil properties limit the positive effects of land use reversion on carbon storage in Eastern Australia
Publisher: Springer Science and Business Media LLC
Date: 07-12-2015
DOI: 10.1038/SREP17866
Abstract: Australia’s “Direct Action” climate change policy relies on purchasing greenhouse gas abatement from projects undertaking approved abatement activities. Management of soil organic carbon (SOC) in agricultural soils is an approved activity, based on the expectation that land use change can deliver significant changes in SOC. However, there are concerns that climate, topography and soil texture will limit changes in SOC stocks. This work analyses data from 1482 sites surveyed across the major agricultural regions of Eastern Australia to determine the relative importance of land use vs. other drivers of SOC. Variation in land use explained only 1.4% of the total variation in SOC, with aridity and soil texture the main regulators of SOC stock under different land uses. Results suggest the greatest potential for increasing SOC stocks in Eastern Australian agricultural regions lies in converting from cropping to pasture on heavy textured soils in the humid regions.
Stoichiometric controls upon low molecular weight carbon decomposition
Publisher: Elsevier BV
Date: 12-2014
Rewetting CO2 pulses in Australian agricultural soils and the influence of soil properties
Publisher: Springer Science and Business Media LLC
Date: 13-07-2010
The effects of vegetation and burning on the chemical composition of soil organic matter of a volcanic ash soil as shown by C-13 NMR spectroscopy .2. Density fractions
Publisher: Elsevier BV
Date: 04-1997
Organic anion-to-acid ratio influences pH change of soils differing in initial pH
Publisher: Springer Science and Business Media LLC
Date: 27-03-2014
Factors affecting ammonium capture by some Victorian lignites
Publisher: Informa UK Limited
Date: 08-03-2022
DOI: 10.1080/09593330.2022.2048315
Abstract: HighlightsVictorian lignites were assessed for their
Chemical composition and bioavailability of thermally altered Pinus resinosa (Red pine) wood
Publisher: Elsevier BV
Date: 09-2002
Prospects and problems of simple linear models for estimating symbiotic N2 fixation by crop and pasture legumes
Publisher: Springer Science and Business Media LLC
Date: 25-08-2010
Rapid changes in carbon and phosphorus after rewetting of dry soil
Publisher: Springer Science and Business Media LLC
Date: 17-09-2011
Using the power of C-13 NMR to interpret infrared spectra of soil organic matter: A two-dimensional correlation spectroscopy approach
Publisher: Elsevier BV
Date: 05-2013
Carbon sequestration under subtropical perennial pastures I: Overall trends
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13111
Abstract: The use of subtropical perennial grasses in temperate grazing systems is increasingly being promoted for production and environmental benefits. This study employed a combination of elemental and stable isotope analyses to explore whether pastures sown to either kikuyu (Pennisetum clandestinum) or a combination of panic (Panicum maximum) and Rhodes grass (Chloris gayana) could increase soil organic carbon (SOC) levels in five regions across southern Australia. Carbon was sequestered under kikuyu at a rate of 0.90 ± 0.25 Mg C ha–1 year–1 along the south coast of Western Australia. Lower but still significant sequestration rates were found for kikuyu in South Australia (0.26 ± 0.13 Mg C ha–1 year–1). No changes in SOC were found for panic–Rhodes grass pasture systems in the northern district of Western Australia. Additionally, we found no changes in SOC when kikuyu-based pastures were established on formerly cropped paddocks in the Namoi Catchment of New South Wales. Stable isotope results corroborated these findings and suggested that, where SOC has accumulated, the gains have been dominated by SOC derived from the perennial vegetation and have been concentrated in the upper 10 cm of soil.
Predicting contents of carbon and its component fractions in Australian soils from diffuse reflectance mid-infrared spectra
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13077
Abstract: Quantifying the content and composition of soil carbon in the laboratory is time-consuming, requires specialised equipment and is therefore expensive. Rapid, simple and low-cost accurate methods of analysis are required to support current interests in carbon accounting. This study was completed to develop national and state-based models capable of predicting soil carbon content and composition by coupling diffuse reflectance mid-infrared (MIR) spectra with partial least-squares regression (PLSR) analyses. Total, organic and inorganic carbon contents were determined and MIR spectra acquired for 20 495 soil s les collected from 4526 locations from soil depths to 1 m within Australia’s agricultural regions. However, all subsequent MIR/PLSR models were developed using soils only collected from the 0–10, 10–20 and 20–30 cm depth layers. The extent of grinding applied to air-dried soil s les was found to be an important determinant of the variability in acquired MIR spectra. After standardisation of the grinding time, national MIR/PLSR models were developed using an independent test-set validation approach to predict the square-root transformed contents of total, organic and inorganic carbon and total nitrogen. Laboratory fractionation of soil organic carbon into particulate, humus and resistant forms was completed on 312 soil s les. Reliable national MIR/PLSR models were developed using cross-validation to predict the contents of these soil organic carbon fractions however, further work is required to enhance the representation of soils with significant contents of inorganic carbon. Regional MIR/PLSR models developed for total, organic and inorganic carbon and total nitrogen contents were found to produce more reliable and accurate predictions than the national models. The MIR/PLSR approach offers a more rapid and more cost effective method, relative to traditional laboratory methods, to derive estimates of the content and composition of soil carbon and total nitrogen content provided that the soils are well represented by the calibration s les used to build the predictive models.
Chemical characterisation of bog peat and dried peat of the Australian Alps
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/SR04014
Abstract: The importance of bogs in the catchment hydrology of the Australian Alps has been long recognised but little studied. Damaged bogs are thought to be the source of dried peats now common throughout the Alps. We described the characteristics of a bog peat and a dried peat, to better understand the relationship between the two. Standard chemical properties of peat were measured: pH, loss on ignition, gravimetric contents of carbon and nitrogen, and electrical conductivity. We also measured the concentrations of total and plant-available elements, and the chemical composition of the organic carbon, leading to a measure of the extent of decomposition. The results suggest that this is a typical Sphagnum bog peat—low pH, high carbon content—and the distribution of carbon groups and other elements reflect the stable water source of this groundwater-fed Sphagnum bog. The properties of the dried peat were most similar to the catotelm (lower layer) of the bog peat. This resemblance, combined with decades of field observations, indicates that dried peat may form from the catotelm of bog peat, after the acrotelm (upper layer) dries and erodes. These results have implications for the management of Alps catchments, and further studies are needed to ascertain the hydrologic and carbon cycling roles of organic soils in the Australian Alps.
Acid hydrolysis to define a biologically-resistant pool is compromised by carbon loss and transformation
Publisher: Elsevier BV
Date: 09-2013
Model organic compounds differ in priming effects on alkalinity release in soils through carbon and nitrogen mineralisation
Publisher: Elsevier BV
Date: 08-2012
The future of Blue Carbon science
Publisher: Springer Science and Business Media LLC
Date: 05-09-2019
DOI: 10.1038/S41467-019-11693-W
Abstract: The term Blue Carbon (BC) was first coined a decade ago to describe the disproportionately large contribution of coastal vegetated ecosystems to global carbon sequestration. The role of BC in climate change mitigation and adaptation has now reached international prominence. To help prioritise future research, we assembled leading experts in the field to agree upon the top-ten pending questions in BC science. Understanding how climate change affects carbon accumulation in mature BC ecosystems and during their restoration was a high priority. Controversial questions included the role of carbonate and macroalgae in BC cycling, and the degree to which greenhouse gases are released following disturbance of BC ecosystems. Scientists seek improved precision of the extent of BC ecosystems techniques to determine BC provenance understanding of the factors that influence sequestration in BC ecosystems, with the corresponding value of BC and the management actions that are effective in enhancing this value. Overall this overview provides a comprehensive road map for the coming decades on future research in BC science.
Changes in water content of two agricultural soils does not alter labile P and C pools
Publisher: Springer Science and Business Media LLC
Date: 30-07-2011
The knowns, known unknowns and unknowns of sequestration of soil organic carbon
Publisher: Elsevier BV
Date: 2013
Quantifying blue carbon and nitrogen stocks in surface soils of temperate coastal wetlands
Publisher: CSIRO Publishing
Date: 25-06-2021
DOI: 10.1071/SR20040
Abstract: Coastal wetlands are carbon and nutrient sinks that capture large amounts of atmospheric CO2 and runoff of nutrients. ‘Blue carbon’ refers to carbon stored within resident vegetation (e.g. mangroves, tidal marshes and seagrasses) and soil of coastal wetlands. This study aimed to quantify the impact of vegetation type on soil carbon stocks (organic and inorganic) and nitrogen in the surface soils (0–10 cm) of mangroves and tidal marsh habitats within nine temperate coastal blue carbon wetlands in South Australia. Results showed differences in surface soil organic carbon stocks (18.4 Mg OC ha–1 for mangroves 17.6 Mg OC ha–1 for tidal marshes), inorganic carbon (31.9 Mg IC ha–1 for mangroves 35.1 Mg IC ha–1 for tidal marshes), and total nitrogen (1.8 Mg TN ha–1 for both) were not consistently driven by vegetation type. However, mangrove soils at two sites (Clinton and Port Augusta) and tidal marsh soils at one site (Torrens Island) had larger soil organic carbon (SOC) stocks. These results highlighted site-specific differences in blue carbon stocks between the vegetation types and spatial variability within sites. Further, differences in spatial distribution of SOC within sites corresponded with variations in soil bulk density (BD). Results highlighted a link between SOC and BD in blue carbon soils. Understanding the drivers of carbon and nitrogen storage across different blue carbon environments and capturing its spatial variability will help improve predictions of the contribution these ecosystems to climate change mitigation.
The biochemical and elemental compositions of marine plankton: A NMR perspective
Publisher: Elsevier BV
Date: 04-2002
Deriving hillslope sediment budgets in wildfire-affected forests using fallout radionuclide tracers
Publisher: Elsevier BV
Date: 03-2009
Geochemical analyses reveal the importance of environmental history for blue carbon sequestration
Publisher: American Geophysical Union (AGU)
Date: 07-2017
DOI: 10.1002/2017JG003775
Australian vegetated coastal ecosystems as global hotspots for climate change mitigation
Publisher: Springer Science and Business Media LLC
Date: 02-10-2019
DOI: 10.1038/S41467-019-12176-8
Abstract: Policies aiming to preserve vegetated coastal ecosystems (VCE tidal marshes, mangroves and seagrasses) to mitigate greenhouse gas emissions require national assessments of blue carbon resources. Here, we present organic carbon (C) storage in VCE across Australian climate regions and estimate potential annual CO 2 emission benefits of VCE conservation and restoration. Australia contributes 5–11% of the C stored in VCE globally (70–185 Tg C in aboveground biomass, and 1,055–1,540 Tg C in the upper 1 m of soils). Potential CO 2 emissions from current VCE losses are estimated at 2.1–3.1 Tg CO 2 -e yr -1 , increasing annual CO 2 emissions from land use change in Australia by 12–21%. This assessment, the most comprehensive for any nation to-date, demonstrates the potential of conservation and restoration of VCE to underpin national policy development for reducing greenhouse gas emissions.
Controls on the oxidative ratio of net primary production in agricultural ecosystems
Publisher: Springer Science and Business Media LLC
Date: 22-08-2014
Similar composition but differential stability of mineral retained organic matter across four classes of clay minerals
Publisher: Springer Science and Business Media LLC
Date: 08-07-2014
Estimating change in soil organic carbon using legacy data as the baseline: issues, approaches and lessons to learn
Publisher: CSIRO Publishing
Date: 2014
DOI: 10.1071/SR13081
Abstract: The importance of soil organic carbon (SOC) in maintaining soil health is well understood. However, there is growing interest in studying SOC with an emphasis on quantifying its changes in space and time. This is because of the potential for soil to be used to sequester atmospheric C. There are many issues which make this difficult, for ex le shortcomings in s ling designs, and differences in vertical and lateral s ling supports between surveys, particularly if legacy data are used as the baseline survey. In this study, we systematically work through these issues and show how a protocol can be developed using design-based and model-based statistical approaches to estimate changes in SOC in space and time at different spatial supports. We demonstrate this protocol in a small subcatchment in the upper Namoi valley for estimating the change in SOC over time, whereby the baseline dataset was collected during 1999–2001 and is compared with a dataset from November 2010. The results from both design-based and model-based approaches revealed a drop in SOC across the catchment between the two survey periods. A 0.26% drop in SOC was reported globally across the catchment. Nevertheless, the change in SOC reported for both approaches was not statistically significant.
Effects of plant functional group removal on structure and function of soil communities across contrasting ecosystems
Publisher: Wiley
Date: 07-04-2019
DOI: 10.1111/ELE.13266
Abstract: Loss of plant ersity has an impact on ecosystems worldwide, but we lack a mechanistic understanding of how this loss may influence below-ground biota and ecosystem functions across contrasting ecosystems in the long term. We used the longest running bio ersity manipulation experiment across contrasting ecosystems in existence to explore the below-ground consequences of 19 years of plant functional group removals for each of 30 contrasting forested lake islands in northern Sweden. We found that, against expectations, the effects of plant removals on the communities of key groups of soil organisms (bacteria, fungi and nematodes), and organic matter quality and soil ecosystem functioning (decomposition and microbial activity) were relatively similar among islands that varied greatly in productivity and soil fertility. This highlights that, in contrast to what has been shown for plant productivity, plant bio ersity loss effects on below-ground functions can be relatively insensitive to environmental context or variation among widely contrasting ecosystems.
Relationships between carbon dioxide emission and soil properties in salt-affected landscapes
Publisher: Elsevier BV
Date: 03-2011
Australian Soil Carbon Research Program
Publisher: No publisher found
Date: 2013
Does Solid-state 15N NMR Spectroscopy Detect all Soil Organic Nitrogen?
Publisher: Springer Science and Business Media LLC
Date: 09-2005
A space-time observation system for soil organic carbon
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/SR14178
Abstract: In this paper, we present a framework for a space–time observation system for soil organic carbon (STOS-SOC). We propose that the RothC model be embedded within the STOS-SOC, which is driven by satellite-derived inputs and readily available geospatial inputs, such as digital soil maps. In particular, advances in remote sensing have enabled the development of satellite products that represent key inputs into soil carbon models, ex les being evapotranspiration and biomass inputs to soil, which characterise space–time variations in management and land use. Starting from an initial calibrated base for prediction, as new observations are acquired, data assimilation techniques could be used to optimise calibration algorithms and predicted model outputs. We present initial results obtained from the implementation of the proposed STOS-SOC approach to the 1445-km2 Cox’s Creek catchment in northern New South Wales, Australia. Our results showed that use of satellite-derived biomass inputs with a MODIS satellite product (MOD17A3) improved the accuracy of simulations by 16% compared with carbon inputs derived through other methods normally adopted in the spatialisation of the RothC model. We further discuss the possibility of improving the capabilities of the STOS-SOC for future applications.
Habitat selective factors influencing the structural composition and functional capacity of microbial communities in agricultural soils
Publisher: Elsevier BV
Date: 03-2008
Measurement of asymbiotic N2 fixation in Australian agriculture [review]
Publisher: Elsevier BV
Date: 12-2008
Related Organisations
Commonwealth Scientific And Industrial Research Organisation
Location: Australia
Related Funding Activities
Discovery Projects - Grant ID: DP0877882
Start Date: 2008
End Date: 12-2011
Amount: $300,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP0662978
Start Date: 03-2006
End Date: 12-2009
Amount: $260,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP120104100
Start Date: 2012
End Date: 12-2016
Amount: $310,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200100575
Start Date: 06-2020
End Date: 12-2024
Amount: $559,850.00
Funder: Australian Research Council
View Funded Activity