ORCID Profile
0000-0003-2381-9601
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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)
Microbial Ecology | Soil Sciences | Other Biological Sciences | Environmental Technologies | Global Change Biology | Environmental Engineering | Soil Chemistry | Soil Physics | Inorganic Geochemistry | Natural Resource Management | Land And Parks Management | Environmental Impact Assessment
ANZSRC Socio-Economic Objective (SEO)
Atmospheric composition | Land and water management | Field crops | Management of Solid Waste from Mineral Resource Activities | Rehabilitation of Degraded Mining Environments | Land and water management |
Related Links
Publications
Is land condition a useful indicator of soil organic carbon stock in Australia’s northern grazing land?
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/RJ15097
Abstract: The grazing lands of northern Australia contain a substantial soil organic carbon (SOC) stock due to the large land area. Manipulating SOC stocks through grazing management has been presented as an option to offset national greenhouse gas emissions from agriculture and other industries. However, research into the response of SOC stocks to a range of management activities has variously shown positive, negative or negligible change. This uncertainty in predicting change in SOC stocks represents high project risk for government and industry in relation to SOC sequestration programs. In this paper, we seek to address the uncertainty in SOC stock prediction by assessing relationships between SOC stocks and grazing land condition indicators. We reviewed the literature to identify land condition indicators for analysis and tested relationships between identified land condition indicators and SOC stock using data from a paired-site s ling experiment (10 sites). We subsequently collated SOC stock datasets at two scales (quadrat and paddock) from across northern Australia (329 sites) to compare with the findings of the paired-site s ling experiment with the aim of identifying the land condition indicators that had the strongest relationship with SOC stock. The land condition indicators most closely correlated with SOC stocks across datasets and analysis scales were tree basal area, tree canopy cover, ground cover, pasture biomass and the density of perennial grass tussocks. In combination with soil type, these indicators accounted for up to 42% of the variation in the residuals after climate effects were removed. However, we found that responses often interacted with soil type, adding complexity and increasing the uncertainty associated with predicting SOC stock change at any particular location. We recommend that caution be exercised when considering SOC offset projects in northern Australian grazing lands due to the risk of incorrectly predicting changes in SOC stocks with change in land condition indicators and management activities for a particular paddock or property. Despite the uncertainty for generating SOC sequestration income, undertaking management activities to improve land condition is likely to have desirable complementary benefits such as improving productivity and profitability as well as reducing adverse environmental impact.
Effects of long-term cultivation on phosphorus (P) in five low-input, subtropical Australian soils
Publisher: Elsevier BV
Date: 2018
Simulating soybean–wheat cropping system: APSIM model parameterization and validation
Publisher: Elsevier BV
Date: 05-2012
Effects of litter and fine root composition on their decomposition in a rhodic paleustalf under different land uses
Publisher: Informa UK Limited
Date: 10-2006
Soil carbon and nitrogen pools, their depth distribution and stocks following plantation establishment in south east Queensland, Australia
Publisher: Elsevier BV
Date: 02-2020
Conversion of sub-tropical native vegetation to introduced conifer forest: Impacts on below-ground and above-ground carbon pools
Publisher: Elsevier BV
Date: 06-2016
Soil carbon sequestration and density distribution in a Vertosol under different farming practices
Publisher: CSIRO Publishing
Date: 2004
DOI: 10.1071/SR04023
Abstract: Abstract Agricultural soils play an important role in the global carbon (C) cycling and can act as a significant C sink if managed properly. The long-term (33 years) effects of no till (NT) v. conventional till (CT), stubble retention (SR) v. stubble burning (SB), and N fertiliser application (NF) v. nil N fertilisation (N0) on soil organic C sequestration, and their seasonal variations during the fallow period, were studied in a winter cereal–summer fallow cropping system under semi-arid subtropical climate in Queensland, Australia. The function of different density fractions of soil organic C in determining total organic C (TOC) dynamics and sequestration was investigated. Significant effect of NT, SR, or NF on soil organic C level was observed only in the top 10 cm soil and when they were practiced together, with the TOC contents being 1.1 to 3.4 t/ha higher under NT + NF + SR than under other treatments. There were significant seasonal fluctuations in TOC contents at different stages of the fallow period, and the lowest levels of TOC and treatment effects were observed in the late fallow period. Density fractionation of soil organic C showed that light fraction C ( .6 g/cm3) declined rapidly during the fallow period and did not accumulate substantially in soil. TOC dynamics, either as a consequence of seasonal variations or as a long-term response to different farming practices, were predominantly controlled by the changes in the heavy fraction C ( .6 g/cm3).
Green waste compost reduces nitrous oxide emissions from feedlot manure applied to soil
Publisher: Elsevier BV
Date: 15-03-2010
How Important is the Quality of Organic Amendments in Relation to Mineral N Availability in Soils?
Publisher: Springer Science and Business Media LLC
Date: 16-02-2013
Effect of added nitrogen on plant litter decomposition depends on initial soil carbon and nitrogen stoichiometry
Publisher: Elsevier BV
Date: 12-2015
SOC Stock Changes and Greenhouse Gas Emissions Following Tropical Land Use Conversions to Plantation Crops on Mineral Soils, with a Special Focus on Oil Palm and Rubber Plantations
Publisher: MDPI AG
Date: 09-2018
DOI: 10.3390/AGRICULTURE8090133
Abstract: The increasing global demand for vegetable oils has resulted in a significant increase in the area under oil palm in the tropics during the last couple of decades, and this is projected to increase further. The Roundtable on Sustainable Palm Oil discourages the conversion of peatlands to oil palm and rubber plantations. However, our understanding of the effects on soil organic carbon (SOC) stocks and associated greenhouse gas (GHG) emissions of land use conversion is incomplete, especially for mineral soils under primary forests, secondary forests, rubber and other perennial plantations in the tropics. In this review we synthesised information on SOC stocks and GHG emissions from tropical mineral soils under forest, oil palm and rubber plantations and other agroecosystems across the tropical regions. We found that the largest SOC losses occurred after land use conversion from primary forest to oil palm and rubber plantations. Secondary forest and pasture lands showed lower SOC losses as well as total GHG (CO2, N2O and CH4) emissions when converted to oil palm and rubber plantations. However, due to the limited data available on all three GHG emissions, there remains high uncertainty in GHG emissions estimates, and regional GHG accounting is more reliable. We recommend long-term monitoring of oil palm and other perennial plantations established on tropical mineral soils on different soil types and regions on SOC stock changes and total GHG emissions and evaluate appropriate management practices to optimise production and sustainable economic returns, and minimise environmental impact.
Microbial energy and matter transformation in agricultural soils
Publisher: Elsevier BV
Date: 08-2017
Carbon dynamics from carbonate dissolution in Australian agricultural soils
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/SR14060
Abstract: Land-use and management practices on limed acidic and carbonate-bearing soils can fundamentally alter carbon (C) dynamics, creating an important feedback to atmospheric carbon dioxide (CO2) concentrations. Transformation of carbonates in such soils and its implication for C sequestration with climate change are largely unknown and there is much speculation about inorganic C sequestration via bicarbonates. Soil carbonate equilibrium is complicated, and all reactants and reaction products need to be accounted for fully to assess whether specific processes lead to a net removal of atmospheric CO2. Data are scarce on the estimates of CaCO3 stocks and the effect of land-use management practices on these stocks, and there is a lack of understanding on the fate of CO2 released from carbonates. We estimated carbonate stocks from four major soil types in Australia (Calcarosols, Vertosols, Kandosols and Chromosols). In -mm rainfall zone, which is important for Australian agriculture, the CaCO3-C stocks ranged from 60.7 to 2542 Mt at 0–0.3 m depth (dissolution zone), and from 260 to 15 660 Mt at 0–1.0 m depth. The combined CaCO3-C stocks in Vertosols, Kandosols and Chromosols were about 30% of those in Calcarosols. Total average CaCO3-C stocks in the dissolution zone represented 11–23% of the stocks present at 0–1.0 m depth, across the four soil types. These estimates provide a realistic picture of the current variation of CaCO3-C stocks in Australia while offering a baseline to estimate potential CO2 emission–sequestration through land-use changes for these soil types. In addition, we provide an overview of the uncertainties in accounting for CO2 emission from soil carbonate dissolution and major inorganic C transformations in soils as affected by land-use change and management practices, including liming of acidic soils and its secondary effects on the mobility of dissolved organic C. We also consider impacts of liming on mineralisation of the native soil C, and when these transformations should be considered a net atmospheric CO2 source or sink.
Nitrogen management is the key for low-emission wheat production in Australia: A life cycle perspective
Publisher: Elsevier BV
Date: 05-2015
Subtropical giant podzol chronosequence reveals that soil carbon stabilisation is not governed by litter quality
Publisher: Springer Science and Business Media LLC
Date: 05-04-2015
Achieving the win–win: targeted agronomy can increase both productivity and sustainability of the rice–wheat system
Publisher: Springer Science and Business Media LLC
Date: 29-11-2022
Soil Organic Carbon Stabilization: Mapping Carbon Speciation from Intact Microaggregates
Publisher: American Chemical Society (ACS)
Date: 17-10-2018
Abstract: The clearing of land for agricultural production depletes soil organic carbon (OC) reservoirs, yet despite their importance, the mechanisms by which C is stabilized in soils remain unclear. Using synchrotron-based infrared microspectroscopy, we have for the first time obtained in situ, laterally resolved data regarding the speciation of C within sections taken from intact free microaggregates from two contrasting soils (Vertisol and Oxisol, 0-20 cm depth) impacted upon by long-term (up to 79 y) agricultural production. There was no apparent gradient in the C concentration from the aggregate surface to the interior for any of the three forms of C examined (aliphatic C, aromatic C, and polysaccharide C). Rather, organo-mineral interactions were of critical importance in influencing overall C stability, particularly for aliphatic C, supporting the hypothesis that microaggregates form through organo-mineral interactions. However, long-term cropping substantially decreased the magnitude of the organo-mineral interactions for all three forms of C. Thus, although organo-mineral interactions are important for OC stability, C forms associated with the mineral phases are not entirely resistant to degradation. These results provide important insights into the underlying mechanisms by which microaggregates form and the factors influencing the persistence of OC in soils.
The role of soil in defining planetary boundaries and the safe operating space for humanity
Publisher: Elsevier BV
Date: 2021
Soil carbon and nitrogen dynamics in a Vertisol following 50 years of no-tillage, crop stubble retention and nitrogen fertilization
Publisher: Elsevier BV
Date: 2020
Soil carbon stock in the tropical rangelands of Australia: Effects of soil type and grazing pressure, and determination of sampling requirement
Publisher: Elsevier BV
Date: 11-2011
Non-target impacts of pesticides on soil N transformations, abundances of nitrifying and denitrifying genes, and nitrous oxide emissions
Publisher: Elsevier BV
Date: 10-2022
DOI: 10.1016/J.SCITOTENV.2022.157043
Abstract: Agriculture is the leading contributor to global nitrous oxide (N
Piggery pond sludge as a nitrogen source for crops. 1. Mineral N supply estimated from laboratory incubations and field application of stockpiled and wet sludge
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/AR04187
Abstract: Piggery pond sludge (PPS) was applied, as-collected (Wet PPS) and following stockpiling for 12 months (Stockpiled PPS), to a sandy Sodosol and clay Vertosol at sites on the Darling Downs of Queensland. Laboratory measures of N availability were carried out on unamended and PPS-amended soils to investigate their value in estimating supplementary N needs of crops in Australia’s northern grains region. Cumulative net N mineralised from the long-term (30 weeks) leached aerobic incubation was described by a first-order single exponential model. The mineralisation rate constant (0.057/week) was not significantly different between Control and PPS treatments or across soil types, when the amounts of initial mineral N applied in PPS treatments were excluded. Potentially mineralisable N (No) was significantly increased by the application of Wet PPS, and increased with increasing rate of application. Application of Wet PPS significantly increased the total amount of inorganic N leached compared with the Control treatments. Mineral N applied in Wet PPS contributed as much to the total mineral N status of the soil as did that which mineralised over time from organic N. Rates of CO2 evolution during 30 weeks of aerobic leached incubation indicated that the Stockpiled PPS was more stabilised (19–28% of applied organic C mineralised) than the Wet PPS (35–58% of applied organic C mineralised), due to higher lignin content in the former. Net nitrate-N produced following 12 weeks of aerobic non-leached incubation was highly correlated with net nitrate-N leached during 12 weeks of aerobic incubation (R2 = 0.96), although it was % of the latter in both sandy and clayey soils. Anaerobically mineralisable N determined by waterlogged incubation of laboratory PPS-amended soil s les increased with increasing application rate of Wet PPS. Anaerobically mineralisable N from field-moist soil was well correlated with net N mineralised during 30 weeks of aerobic leached incubation (R2 = 0.90 sandy soil R2 = 0.93 clay soil). In the clay soil, the amount of mineral N produced from all the laboratory incubations was significantly correlated with field-measured nitrate-N in the soil profile (0–1.5 m depth) after 9 months of weed-free fallow following PPS application. In contrast, only anaerobic mineralisable N was significantly correlated with field nitrate-N in the sandy soil. Anaerobic incubation would, therefore, be suitable as a rapid practical test to estimate potentially mineralisable N following applications of different PPS materials in the field.
Changes in exchangeable cations and micronutrients in soils and grains of long-term, low input cropping systems of subtropical Australia
Publisher: Elsevier BV
Date: 2017
Turnover of organic carbon and nitrogen in soil assessed from δ13C and δ15N changes under pasture and cropping practices and estimates of greenhouse gas emissions
Publisher: Elsevier BV
Date: 11-2013
DOI: 10.1016/J.SCITOTENV.2013.04.101
Abstract: The continuing clearance of native vegetation for pasture, and especially cropping, is a concern due to declines in soil organic C (SOC) and N, deteriorating soil health, and adverse environment impact such as increased emissions of major greenhouse gases (CO2, N2O and CH4). There is a need to quantify the rates of SOC and N budget changes, and the impact on greenhouse gas emissions from land use change in semi-arid subtropical regions where such data are scarce, so as to assist in developing appropriate management practices. We quantified the turnover rate of SOC from changes in δ(13)C following the conversion of C3 native vegetation to C4 perennial pasture and mixed C3/C4 cereal cropping (wheat/sorghum), as well as δ(15)N changes following the conversion of legume native vegetation to non-legume systems over 23 years. Perennial pasture (Cenchrus ciliaris cv. Biloela) maintained SOC but lost total N by more than 20% in the top 0-0.3m depth of soil, resulting in reduced animal productivity from the grazed pasture. Annual cropping depleted both SOC and total soil N by 34% and 38%, respectively, and resulted in decreasing cereal crop yields. Most of these losses of SOC and total N occurred from the >250 μm fraction of soil. Moreover, this fraction had almost a magnitude higher turnover rates than the 250-53 μm and <53 μm fractions. Loss of SOC during the cropping period contributed two-orders of magnitude more CO2-e to the atmosphere than the pasture system. Even then, the pasture system is not considered as a benchmark of agricultural sustainability because of its decreasing productivity in this semi-arid subtropical environment. Introduction of legumes (for N2 fixation) into perennial pastures may arrest the productivity decline of this system. Restoration of SOC in the cropped system will require land use change to perennial ecosystems such as legume-grass pastures or native vegetation.
Biochar and biomass organic amendments shaped different dominance of lithoautotrophs and organoheterotrophs in microbial communities colonizing neutral copper(Cu)-molybdenum(Mo)-gold(Au) tailings
Publisher: Elsevier BV
Date: 2018
Seasonal variation in nitrous oxide and methane emissions from subtropical estuary and coastal mangrove sediments, Australia
Publisher: Wiley
Date: 10-12-2010
DOI: 10.1111/J.1438-8677.2010.00331.X
Abstract: Mangrove sediments can act as sources of the greenhouse trace gases, nitrous oxide (N(2) O) and methane (CH(4) ). Confident reporting of trace gas emissions from mangrove sediments at local levels is important for regional emissions inventories, since small changes in N(2) O and CH(4) fluxes greatly influence greenhouse gas budgets due to their high global warming potentials. It is also important to identify the drivers of trace gas emission, to prioritize management for minimising emissions. We measured N(2) O and CH(4) fluxes and abiotic sediment parameters at midday low tide in winter and summer seasons, at four sites (27°33'S, 152°59'E) ranging from estuary to ocean sub-tropical mangrove sediments, having varied anthropogenic impacts. At all sites, sediment N(2) O and CH(4) emissions were significantly lower during winter (7-26 μg N(2) O m(-2) · h(-1) 47-466 μg CH(4) m(-2) · h(-1)) compared to summer (28-202 μg N(2) Om(-2) · h(-1) 247-1570 μg CH(4) m(-2) · h(-1)). Sediment temperature, ranging from 18 to 33°C, strongly influenced N(2) O and CH(4) emissions. Highest emissions (202 μg N(2) O m(-2) · h(-1), 1570 μg CH(4) m(-2) · h(-1) ) were detected at human-impacted estuary sites, which generally had higher total carbon (<8%) and total nitrogen (<0.4%) in sediments and reduced salinity (<16 dS · m(-1)). Large between-site variation highlights the need for regular monitoring of sub-tropical mangroves to capture short-lived, episodic N(2) O and CH(4) flux events that are affected by sediment biophysico-chemical conditions at site level. This is important, particularly at sites receiving anthropogenic nutrients, and that have variable freshwater inputs and tidal hydrology.
Conservation agriculture enhances the rice-wheat system of the Eastern Gangetic Plains in some environments, but not in others
Publisher: Elsevier BV
Date: 05-2021
Drying and rewetting effects on organic matter mineralisation of contrasting soils after 36 years of storage
Publisher: Elsevier BV
Date: 05-2019
Managing cattle grazing intensity: effects on soil organic matter and soil nitrogen
Publisher: CSIRO Publishing
Date: 2015
DOI: 10.1071/SR14236
Abstract: Extensive cattle grazing is the dominant land use in northern Australia. It has been suggested that grazing intensity and rainfall have profound effects on the dynamics of soil nutrients in northern Australia’s semi-arid rangelands. Previous studies have found positive, neutral and negative effects of grazing pressure on soil nutrients. These inconsistencies could be due to short-term experiments that do not capture the slow dynamics of some soil nutrients and the effects of interannual variability in rainfall. In a long-term cattle grazing trial in northern Australia on Brown Sodosol–Yellow Kandosol complex, we analysed soil organic matter and mineral nitrogen in surface soils (0–10 cm depth) 11, 12 and 16 years after trial establishment on experimental plots representing moderate stocking (stocked at the long-term carrying capacity for the region) and heavy stocking (stocked at twice the long-term carrying capacity). Higher soil organic matter was found under heavy stocking, although grazing treatment had little effect on mineral and total soil nitrogen. Interannual variability had a large effect on soil mineral nitrogen, but not on soil organic matter, suggesting that soil nitrogen levels observed in this soil complex may be affected by other indirect pathways, such as climate. The effect of interannual variability in rainfall and the effects of other soil types need to be explored further.
Brave new green world - Consequences of a carbon economy for the conservation of Australian biodiversity
Publisher: Elsevier BV
Date: 05-2013
How we used APSIM to simulate conservation agriculture practices in the rice-wheat system of the Eastern Gangetic Plains
Publisher: Elsevier BV
Date: 2022
Temperature sensitivity and carbon release in an acidic soil amended with lime and mulch
Publisher: Elsevier BV
Date: 02-2014
Puddled and zero-till unpuddled transplanted rice are each best suited to different environments – An example from two diverse locations in the Eastern Gangetic Plains of Bangladesh
Publisher: Elsevier BV
Date: 03-2021
Magnitude and biophysical regulators of methane emission and consumption in the Australian agricultural, forest, and submerged landscapes: a review
Publisher: Springer Science and Business Media LLC
Date: 02-11-2007
Soil carbon turnover and sequestration in native subtropical tree plantations
Publisher: Elsevier BV
Date: 08-2007
Soil nitrogen status and turnover in subtropical leucaena-grass pastures as quantified by δ15N natural abundance
Publisher: Elsevier BV
Date: 03-2018
Initiation of soil formation in weathered sulfidic Cu-Pb-Zn tailings under subtropical and semi-arid climatic conditions
Publisher: Elsevier BV
Date: 08-2018
DOI: 10.1016/J.CHEMOSPHERE.2018.04.037
Abstract: Field evidence has been scarce about soil (or technosol) formation and direct phytostabilization of base metal mine tailings under field conditions. The present study evaluated key attributes of soil formation in weathered and neutral Cu-Pb-Zn tailings subject to organic amendment (WC: woodchips) and colonization of pioneer native plant species (mixed native woody and grass plant species) in a 2.5-year field trial under subtropical and semi-arid climatic conditions. Key soil indicators of engineered soil formation process were characterized, including organic carbon fractions, aggregation, microbial community and key enzymatic activities. The majority (64-87%) of the OC was stabilized in microaggregate or organo-mineral complexes in the amended tailings. The levels of OC and water soluble OC were elevated by 2-3 folds across the treatments, with the highest level in the treatment of WC and plant colonization (WC+P). Specifically, the WC+P treatment increased the proportion of water stable macroaggregates. Plants further contributed to the N rich organic matter in the tailings, favouring organo-mineral interactions and organic stabilization. Besides, the plants played a major role in boosting microbial biomass and activities in the treated tailings. WC and plants enhanced the contents of organic carbon (OC) associated with aggregates (e.g., physically protected OC), formation of water-stable aggregates (e.g., micro and macroaggregates), chemical buffering capacity (e.g., cation exchange capacity). Microbial community and enzymatic activities were also stimulated in the amended tailings. The present results showed that the formation of functional technosol was initiated in the eco-engineered and weathered Cu-Pb-Zn tailings under field conditions for direct phytostabilization.
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
Modelling N mineralization from green manure and farmyard manure from a laboratory incubation study
Publisher: Elsevier BV
Date: 02-2011
Changes in soil water storage with no-tillage and crop residue retention on a Vertisol: Impact on productivity and profitability over a 50 year period
Publisher: Elsevier BV
Date: 11-2019
Enrichment of natural 15N abundance during soil N losses under 20 years of continuous cereal cropping
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.08.192
Abstract: It is generally accepted that the enrichment of natural
Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping 1. Total and labile carbon
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/SR04044
Abstract: Mulga (Acacia aneura) dominated vegetation originally occupied 11.2 Mha in Queensland, of which 12% has been cleared, mostly for pasture production, but some areas are also used for cereal cropping. Since mulga communities generally occupy fragile soils, mostly Kandosols and Tenosols, in semi-arid environments, clearing of mulga, which continues at a rate of at least 35 000 ha/year in Queensland, has considerable impact on soil organic carbon (C), and may also have implications for the greenhouse gas emissions associated with land use change in Australia. We report here the changes in soil C and labile C pools following mulga clearing to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for 20 years in a study using paired sites. Soil organic C in the top 0.05 m of soil declined by 31% and 35% under buffel pasture and cropping, respectively. Land use change from mulga to buffel and cropping led to declines in soil organic C of 2.4 and 4.7 t/ha, respectively, from the top 0.3 m of soil. Using changes in the δ13C values of soil organic C as an approximate representation of C derived from C3 and C4 vegetation from mulga and buffel, respectively, up to 31% of soil C was C4-derived after 20 years of buffel pasture. The turnover rates of mulga-derived soil C ranged from 0.035/year in the 0–0.05 m depth to 0.008/year in the 0.6–1 m depths, with respective turnover times of 29 and 133 years. Soil organic matter quality, as measured by the proportion/amount of labile fraction C (light fraction, 1.6 t/m3) declined by 55% throughout the soil profile (0–1 m depth) under both pasture and cropping. There is immediate concern for the long-term sustainable use of land where mulga has been cleared for pasture and/or cropping with a continuing decline in soil organic matter quality and, hence, soil fertility and biomass productivity. In addition, the removal of mulga forest over a 20-year period in Queensland for pasture and cropping may have contributed to the atmosphere at least 12 Mt CO2-equivalents.
Agricultural management practices impacted carbon and nutrient concentrations in soil aggregates, with minimal influence on aggregate stability and total carbon and nutrient stocks in contrasting soil
Publisher: Elsevier BV
Date: 05-2018
Effect of long-term no-tillage and nitrogen fertilization on phosphorus distribution in bulk soil and aggregates of a Vertisol
Publisher: Elsevier BV
Date: 2021
Review of crop‐specific tolerance limits to acidity, salinity, and sodicity for seventeen cereal, pulse, and oilseed crops common to rainfed subtropical cropping systems
Publisher: Wiley
Date: 15-03-2021
DOI: 10.1002/LDR.3915
Abstract: Soil constraints limit crop water and nutrient extraction and lead to yield loss globally. In rainfed agriculture, the selection of crop species more likely to yield well under constrained conditions is an important management tool. However, information on the most appropriate crops is often difficult to access due to its publication in a wide range of disparate sources and the various measures of crop tolerance used. This study aimed to improve our ability to identify crops for constrained areas in rainfed subtropical cropping systems by compiling published information that had assessed the grain yield response to acidic, saline, or sodic conditions of 17 cereal, pulse, and oilseed crops. This information was used to develop a 'traffic light' system for salinity and acidity to provide guidance on when soil pH or the electrical conductivity of a saturated soil extract (EC e ) is likely to be 'good', 'potentially limiting', or 'poor' for grain yield. Crops were also ranked according to their likely ability to yield well under saline, acidic, or sodic conditions. For all crops, the point at which grain yield was affected by soil constraints was variable and there was often only a small amount of published information available to help guide the identification of tolerance limits and rankings, particularly for sodicity. Many studies were also conducted under experimental conditions that differed from rainfed farming, which can affect the transferability of results. Confidence in the tolerance limits and rankings is thus only moderate and further work is required to confirm their applicability.
Free light fraction carbon and nitrogen, a physically uncomplexed soil organic matter distribution within subtropical grass and leucaena-grass pastures
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR18162
Abstract: Quantifying the size and turnover of physically uncomplexed soil organic matter (SOM) is crucial for the understanding of nutrient cycling and storage of soil organic carbon (SOC). However, the C and nitrogen (N) dynamics of SOM fractions in leucaena (Leucaena leucocephala)–grass pastures remains unclear. We assessed the potential of leucaena to sequester labile, free light fraction (fLF) C and N in soil by estimating the origin, quantity and vertical distribution of physically unprotected SOM. The soil from a chronosequence of seasonally grazed leucaena stands (0–40 years) was s led to a depth of 0.2m and soil and fLF were analysed for organic C, N and δ13C and δ15N. On average, the fLF formed 20% of SOC and 14% of total N stocks in the upper 0.1m of soil from leucaena rows and showed a peak of fLF-C and fLF-N stocks in the 22-year-stand. The fLF δ13C and fLF δ15N values indicated that leucaena produced 37% of fLF-C and 28% of fLF-N in the upper 0.1m of soil from leucaena rows. Irrespective of pasture type or soil depth, the majority of fLF-C originated from the accompanying C4 pasture-grass species. This study suggests that fLF-C and fLF-N, the labile SOM, can form a significant portion of total SOM, especially in leucaena–grass pastures.
Tillage history and crop residue input enhanced native carbon mineralisation and nutrient supply in contrasting soils under long-term farming systems
Publisher: Elsevier BV
Date: 10-2019
Effects of land-use change and management on soil carbon and nitrogen in the Brigalow Belt, Australia: I. Overview and inventory
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/RJ16009
Abstract: Soil and land-management interactions in Australian native-forest regrowth remain a major source of uncertainty in the context of the global carbon economy. We s led soil total organic C (TOC) and soil total N (TN) stocks at 45 sites within the Brigalow ecological community of the Brigalow Belt bioregion, Queensland, Australia. The sites were matched as triplets representing three land uses, specifically: uncleared native brigalow forest (‘Remnant’) grassland pasture (‘Pasture’), derived by clearing native vegetation and maintained as pasture for a minimum of 10 years, and regrowing native brigalow forest (‘Regrowth’, stand ages ranging from 10 to 58 years) that had developed spontaneously after past vegetation clearing for pasture establishment. Soil TOC fractions and natural abundance of soil C and N isotopes were examined to obtain insight into C and N dynamics. An updated above- and belowground carbon budget for the bioregions was generated. Average soil TOC stocks at 0–0.3-m depth ranged from 19 to 79 Mg ha–1 and soil TN stocks from 1.8 to 7.1 Mg ha–1 (2.5th and 97.5th percentiles, respectively). A trend in stocks was apparent with land use: Remnant Regrowth ≅ Pasture sites. Soil δ13C ranged from –14 to –27‰, and soil δ15N ranged from 4‰ to 17‰, in general reflecting the difference between Pasture (C4-dominated) land use and N2-fixing (C3-dominated) Remnant and Regrowth. Mid-infrared spectroscopy predicted C fractions as a percentage of soil TOC stock, which ranged from 5% to 60% (particulate), 20–80% (humus) and 9–30% (resistant/inert). The geo-referenced soil and management information we collected is important for the calibration of C models, for the estimation of national C accounts, and to inform policy developments in relation to land-resource management undertaken within the Brigalow Belt bioregions of Australia.
Effect of 50 Years of No-Tillage, Stubble Retention, and Nitrogen Fertilization on Soil Respiration, Easily Extractable Glomalin, and Nitrogen Mineralization
Publisher: MDPI AG
Date: 08-01-2022
Abstract: In subtropical regions, we have an incomplete understanding of how long-term tillage, stubble, and nitrogen (N) fertilizer management affects soil biological functioning. We examined a subtropical site managed for 50 years using varying tillage (conventional till (CT) and no-till (NT)), stubble management (stubble burning (SB) and stubble retention (SR)), and N fertilization (0 (N0), 30 (N30), and 90 (N90) kg ha−1 y−1) to assess their impact on soil microbial respiration, easily extractable glomalin-related soil protein (EEGRSP), and N mineralization. A significant three-way tillage × stubble × N fertilizer interaction was observed for soil respiration, with NT+SB+N0 treatments generally releasing the highest amounts of CO2 over the incubation period (1135 mg/kg), and NT+SR+N0 treatments releasing the lowest (528 mg/kg). In contrast, a significant stubble × N interaction was observed for both EEGRSP and N mineralization, with the highest concentrations of both EEGRSP (2.66 ± 0.86 g kg−1) and N mineralization (30.7 mg/kg) observed in SR+N90 treatments. Furthermore, N mineralization was also positively correlated with EEGRSP (R2 = 0.76, p 0.001), indicating that EEGRSP can potentially be used as an index of soil N availability. Overall, this study has shown that SR and N fertilization have a positive impact on soil biological functioning.
Genetic Diversity in Barley and Wheat for Tolerance to Soil Constraints
Publisher: MDPI AG
Date: 02-11-2016
Effects of land-use change and management on soil carbon and nitrogen in the Brigalow Belt, Australia: II. Statistical models to unravel the climate-soil-management interaction
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/RJ16010
Abstract: The impact of grazing on soil carbon (C) and nitrogen (N) cycles is complex, and across a large area it can be difficult to uncover the magnitude of the effects. Here, we have linked two common approaches to statistical modelling – regression trees and linear mixed models – in a novel way to explore various aspects of soil C and N dynamics for a large, semiarid bioregion where land use is dominated by grazing. The resulting models, which we term RT-LMM, have the pleasing visual appeal of regression trees, and they account for spatial autocorrelation as per a linear mixed model. Our RT-LMM were developed from explanatory variables that related information on climate, soil and past land management. Response variables of interest were: stocks of soil total organic carbon (TOC), soil total nitrogen (TN), and particulate organic C (POC) the ratio of TOC stock to TN stock and the relative abundance of stable isotopes δ13C and δ15N in the soil. Each variable was s led at the depth interval 0–0.3 m. The interactions of land use with, in particular, air temperature and soil phosphorus were strong, but three principal management-related effects emerged: (i) the use of fire to clear native vegetation reduced stocks of TOC and TN, and the TOC : TN ratio, by 25%, 19% and 9%, respectively, suggesting that TOC is more sensitive to fire than TN (ii) conversion of native vegetation to pasture enriched soil with δ13C by 1.7 ‰ subsequent regrowth of the native vegetation among the pasture restored δ13C to its original level but there was no corresponding change in TOC stock and, (iii) the time elapsed since clearing reduced POC stocks and the TOC : TN ratio.
Subsoil nitrogen mineralisation and its potential to contribute to NH4 accumulation in a Vertosol
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/SR02038
Abstract: High concentrations of NH4+ (up to 270 kg N/ha) have been observed in a Vertosol below 1 m depth in south-east Queensland. This study examined the possibility that mineralisation associated with the removal of native vegetation (Acacia harpophylla) for cropping was responsible for the production of NH4+. Particularly, the potential contribution of decomposing root material and/or dissolved organic nitrogen (DON) leached into the subsoil after clearing was investigated. The amount of N that was contained within native vegetation root material was determined from an area of native vegetation adjacent to the cleared site containing elevated NH4+ concentrations. In addition, the amount of NH4+ that could be mineralised in the native vegetation soil was determined by monitoring NH4+ concentrations over 360 days in intact cores, and by conducting waterlogged incubations. To determine the rate at which a source of DON leached into the subsoil would mineralise, soil was amended with glutamic acid at a rate of 250 mg N/kg and placed under waterlogged incubation. The possibility that the acidic pH of the subsoil, or the lack of a significant subsoil microbial population, was inhibiting mineralisation was also examined by increasing soil pH from 4.4 to 7.0, and inoculating the subsoil with surface soil microorganisms during waterlogged incubations. Low concentrations of N, approximately 90 kg N/ha between 1.2 and 3 m, were found in the native vegetation root material. In addition, no net N mineralisation was observed in either the extended incubation of intact cores or in the control s les of the waterlogged incubations. Net N mineralisation was also not detected when the subsoil was amended with a source of organic N. Results indicate that this lack of mineralisation is largely due to pH inhibition of the microbial population. It is concluded that the mineralisation of either in situ organic material, or DON transported to the subsoil during leaching events, is unlikely to have significantly contributed to the subsoil NH4 accumulation at the study site.
Impact of agricultural management practices on the nutrient supply potential of soil organic matter under long-term farming systems
Publisher: Elsevier BV
Date: 2018
Nitrogen‐rich microbial products provide new organo‐mineral associations for the stabilization of soil organic matter
Publisher: Wiley
Date: 22-12-2017
DOI: 10.1111/GCB.14009
Abstract: Understanding the cycling of C and N in soils is important for maintaining soil fertility while also decreasing greenhouse gas emissions, but much remains unknown about how organic matter ( OM ) is stabilized in soils. We used nano‐scale secondary ion mass spectrometry (Nano SIMS ) to investigate the changes in C and N in a Vertisol and an Alfisol incubated for 365 days with 13 C and 15 N pulse labeled lucerne ( Medicago sativa L.) to discriminate new inputs of OM from the existing soil OM . We found that almost all OM within the free stable microaggregates of the soil was associated with mineral particles, emphasizing the importance of organo‐mineral interactions for the stabilization of C. Of particular importance, it was also found that 15 N‐rich microbial products originating from decomposition often sorbed directly to mineral surfaces not previously associated with OM . Thus, we have shown that N‐rich microbial products preferentially attach to distinct areas of mineral surfaces compared to C‐dominated moieties, demonstrating the ability of soils to store additional OM in newly formed organo‐mineral associations on previously OM ‐free mineral surfaces. Furthermore, differences in 15 N enrichment were observed between the Vertisol and Alfisol presumably due to differences in mineralogy (smectite‐dominated compared to kaolinite‐dominated), demonstrating the importance of mineralogy in regulating the sorption of microbial products. Overall, our findings have important implications for the fundamental understanding of OM cycling in soils, including the immobilization and storage of N‐rich compounds derived from microbial decomposition and subsequent N mineralization to sustain plant growth.
The sequestration and turnover of soil organic carbon in subtropical leucaena-grass pastures
Publisher: Elsevier BV
Date: 10-2017
Sulfur dynamics in sub-tropical soils of Australia as influenced by long-term cultivation
Publisher: Springer Science and Business Media LLC
Date: 07-01-2016
Biochemical properties of highly mineralised and infertile soil modified by acacia and spinifex plants in northwest Queensland, Australia
Publisher: CSIRO Publishing
Date: 2016
DOI: 10.1071/SR15069
Abstract: Root zone soil properties can significantly influence the establishment of revegetated plant communities and alter their development trajectories in mined landscapes, due to closely coupled biogeochemical linkages between soil and plant systems. The present study aimed to characterise physicochemical and biochemical conditions in soil colonised by slow-growing native plant species: Acacia chisholmii (C3, native leguminous shrub) and Triodia pungens (spinifex C4 grass) in Mt Isa, North-west Queensland, Australia. This is to provide the basis for engineering growth media and root zones suitable for supporting target native plant communities to be revegetated in mined landscapes under subtropical and semiarid climatic conditions. Litter chemistry, soil physicochemical properties, and microbial community structure based on phospholipid fatty acids (PLFAs) biomarker method and activities (basal respiration, net mineralisation, dehydrogenase, invertase, urease and neutral phosphatase activities) were characterised in the surface soils beneath the keystone native plant species. Results showed that soils s led were generally infertile with low levels of total organic carbon (TOC), available nutrients and slow cycling processes with bacteria dominant microbial communities supporting the native plant species. Surface soils underneath acacia and spinifex were modified by in situ litter return, in terms of TOC, and structure and functions of microbial communities. The levels of soil microbial biomass C and N, basal respiration rate and net mineralisation rate in the acacia soil were twice as much as those in the spinifex. Microbial communities in the acacia soil had a greater fungal:bacterial ratio than in the spinifex. On this basis, growth media and root zones for revegetating native acacia-spinifex communities at local mined landscapes may be engineered by using plant organic matter remediation to supply available nutrients and to rehabilitate suitable microbial communities for in situ litter decomposition and nutrient cycling.
What determines soil organic carbon stocks in the grazing lands of north-eastern Australia?
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR13041
Abstract: This study aimed to unravel the effects of climate, topography, soil, and grazing management on soil organic carbon (SOC) stocks in the grazing lands of north-eastern Australia. We s led for SOC stocks at 98 sites from 18 grazing properties across Queensland, Australia. These s les covered four nominal grazing management classes (Continuous, Rotational, Cell, and Exclosure), eight broad soil types, and a strong tropical to subtropical climatic gradient. Temperature and vapour-pressure deficit explained % of the variability of SOC stocks at cumulative equivalent mineral masses nominally representing 0–0.1 and 0–0.3 m depths. Once detrended of climatic effects, SOC stocks were strongly influenced by total standing dry matter, soil type, and the dominant grass species. At 0–0.3 m depth only, there was a weak negative association between stocking rate and climate-detrended SOC stocks, and Cell grazing was associated with smaller SOC stocks than Continuous grazing and Exclosure. In future, collection of quantitative information on stocking intensity, frequency, and duration may help to improve understanding of the effect of grazing management on SOC stocks. Further exploration of the links between grazing management and above- and below-ground biomass, perhaps inferred through remote sensing and/or simulation modelling, may assist large-area mapping of SOC stocks in northern Australia.
Modelling soil organic carbon 1. Performance of APSIM crop and pasture modules against long-term experimental data
Publisher: Elsevier BV
Date: 02-2016
Soil organic carbon is significantly associated with the pore geometry, microbial diversity and enzyme activity of the macro-aggregates under different land uses
Publisher: Elsevier BV
Date: 07-2021
Impact of land use change and soil type on total phosphorus and its fractions in soil aggregates
Publisher: Wiley
Date: 17-12-2020
DOI: 10.1002/LDR.3501
Modelling soil organic carbon 2. Changes under a range of cropping and grazing farming systems in eastern Australia
Publisher: Elsevier BV
Date: 03-2016
Effect of nitrogen fertilizer management and waterlogging on nitrous oxide emission from subtropical sugarcane soils
Publisher: Elsevier BV
Date: 15-03-2010
Diagnosis, extent, impacts, and management of subsoil constraints in the northern grains cropping region of Australia
Publisher: CSIRO Publishing
Date: 2010
DOI: 10.1071/SR09074
Abstract: Productivity of grain crops grown under dryland conditions in north-eastern Australia depends on efficient use of rainfall and available soil moisture accumulated in the period preceding sowing. However, adverse subsoil conditions including high salinity, sodicity, nutrient imbalances, acidity, alkalinity, and high concentrations of chloride (Cl) and sodium (Na) in many soils of the region restrict ability of crop roots to access this stored water and nutrients. Planning for sustainable cropping systems requires identification of the most limiting constraint and understanding its interaction with other biophysical factors. We found that the primary effect of complex and variable combinations of subsoil constraints was to increase the crop lower limit (CLL), thereby reducing plant available water. Among chemical subsoil constraints, subsoil Cl concentration was a more effective indicator of reduced water extraction and reduced grain yields than either salinity or sodicity (ESP). Yield penalty due to high subsoil Cl was seasonally variable, with more in-crop rainfall (ICR) resulting in less negative impact. A conceptual model to determine realistic yield potential in the presence of subsoil Cl was developed from a significant positive linear relationship between CLL and subsoil Cl: Since grid s ling of soil to identify distribution of subsoil Cl, both spatially across landscape and within soil profile, is time-consuming and expensive, we found that electromagnetic induction, coupled with yield mapping and remote sensing of vegetation offers potential to rapidly identify possible subsoil Cl at paddock or farm scale. Plant species and cultivars were evaluated for their adaptations to subsoil Cl. Among winter crops, barley and triticale, followed by bread wheat, were more tolerant of high subsoil Cl concentrations than durum wheat. Chickpea and field pea showed a large decrease in yield with increasing subsoil Cl concentrations and were most sensitive of the crops tested. Cultivars of different winter crops showed minor differences in sensitivity to increasing subsoil Cl concentrations. Water extraction potential of oilseed crops was less affected than cereals with increasing levels of subsoil Cl concentrations. Among summer crops, water extraction potential of millet, mungbean, and sesame appears to be more sensitive to subsoil Cl than that of sorghum and maize however, the differences were significant only to 0.7 m. Among pasture legumes, lucerne was more tolerant to high subsoil Cl concentrations than the others studied. Surface applied gypsum significantly improved wheat grain yield on soils with ESP in surface soil (0–0.10 m). Subsurface applied gypsum at 0.20–0.30 m depth did not affect grain yield in the first year of application however, there was a significant increase in grain yield in following years. Better subsoil P and Zn partially alleviated negative impact of high subsoil Cl. Potential savings from improved N fertilisation decisions for paddocks with high subsoil Cl are estimated at ~$AU10 million per annum.
Inorganic and organic carbon dynamics in a limed acid soil are mediated by plants
Publisher: Elsevier BV
Date: 02-2013
Long-term changes in land use influence phosphorus concentrations, speciation, and cycling within subtropical soils
Publisher: Elsevier BV
Date: 07-2021
Nitrous oxide emission from feedlot manure and green waste compost applied to Vertisols
Publisher: Springer Science and Business Media LLC
Date: 29-07-2009
Application of sustainability indicators, soil organic matter and electrical conductivity, to resource management in the northern grains region
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/EA00186
Abstract: Sustainability is a multifaceted concept. It is expressed here as 'to ensure that the past and current management and use of natural resources does not diminish their capacity to meet economic, environmental, social and aesthetic needs and opportunities of the present and future generations'. Sustainability indicators can be used to monitor responses in condition and trend as a result of natural resource management. We report here 2 case studies that demonstrate the significance of sustainability indicators in discerning trends in land and water resources in the southern Brigalow (Acacia harpophylla) Belt, a major region of the Queensland Murray–Darling Basin. First, soil organic matter was used as a sustainability indicator of soil productivity, soil aggregation, and its association with soil sodicity since these soil attributes affect infiltration rates, runoff and drainage. The second study involved comparing the trends in stream salinity (electrical conductivity) over 35 years and sustainability indicators for a dominant Vertosol in a region used for cereal cropping. Groundwater level and electrical conductivity of a long-term monitoring bore in the Dalby–Chinchilla region, were also analysed to discern trends in salinity and association of the groundwater with soil and stream salinity. Soil organic matter declined exponentially as the cultivation period for cereal cropping increased. This resulted in a reduction in soil nitrogen supply, and lower grain protein and cereal grain yields. The associated effects were reduced soil aggregation and increased soil sodicity. Electrical conductivity of the soil as well as stream water showed weak but declining trends with time. Groundwater level from the long-term monitoring bore near the stream and groundwater salinity showed significantly declining trends over the 35 years s ling period. Groundwater salinity was similar to the Vertosol electrical conductivity at 240–300 cm depths, suggesting groundwater connectivity to the overlaying soil. Thus, use of sustainability indicators provided a strong association among the various attributes of the landscape. However, it is still a challenge to integrate the various sustainability indicators in a landscape context, integrated over space (spatial and geographical distribution), attributes (quality characteristics) and time (trend).
Long-term land use change in Australia from native forest decreases all fractions of soil organic carbon, including resistant organic carbon, for cropping but not sown pasture
Publisher: Elsevier BV
Date: 05-2021
Trends in key soil parameters under conservation agriculture-based sustainable intensification farming practices in the Eastern Ganga Alluvial Plains
Publisher: CSIRO Publishing
Date: 2019
DOI: 10.1071/SR19162
Abstract: Key soil parameters, organic matter, soil pH and plant nutrients determine the capacity of a soil to sustain plant and animal productivity. Conservation agriculture (CA) and crop ersification or intensification may change these soil parameters positively or negatively, which eventually affect long-term sustainability. We monitored these key soil properties (at depths of 0–15 and 15–30 cm) under CA-based sustainable intensification practices: zero-till (ZT), and crop residue retention, and crop rotations on Inceptisols and Entisols in the Eastern Ganga Alluvial Plains from 2014 to 2017. The rainfall of this sub-tropical region is 1273–3201 mm. Soil organic carbon (C) ranged within 0.46–1.13% and generally followed (positive) rainfall gradients. At all sites, the soil under ZT tended to have higher organic C than conventional tillage (CT). Soil pHH2O ranged within 5.7–7.8 across the region. At all sites, soil pH generally decreased under ZT compared to CT. This was most marked at some acidic soil sites where pH decreased by up to 0.4 units the lower the initial soil pH, the higher was the decrease in pH under ZT practice. In contrast, the reverse trend was observed for soil organic C. Partial nutrient balances for N, P and K in rice–wheat and rice–maize systems were positive for N and P (& kg ha–1) but negative for K (up to 90 kg ha–1) under both tillage practices more so under ZT practice even though crop residues were retained. Changes under ZT provide an opportunity to maintain soil organic C. However, remediation measures such as liming and efficient use of fertilisers are required for long-term sustainability of the farming systems in this agriculturally important region of South Asia.
Identifying the spatial variability of soil constraints using multi-year remote sensing
Publisher: Elsevier BV
Date: 09-2011
Quantifying the economic impact of soil constraints on Australian agriculture: A case‐study of wheat
Publisher: Wiley
Date: 14-09-2018
DOI: 10.1002/LDR.3130
Plant roots are more important than temperature in modulating carbon release in a limed acidic soil
Publisher: Wiley
Date: 11-12-2019
DOI: 10.1111/EJSS.12899
Spatial and temporal variation of nitrous oxide and methane flux between subtropical mangrove sediments and the atmosphere
Publisher: Elsevier BV
Date: 02-2007
Stable isotope techniques for quantifying N fertiliser recovery in maize grown in soils with different management histories
Publisher: Springer Science and Business Media LLC
Date: 12-2021
Changes in soil organic carbon and nitrogen after 47 years with different tillage, stubble and fertiliser management in a Vertisol of north-eastern Australia
Publisher: CSIRO Publishing
Date: 2020
DOI: 10.1071/SR19314
Abstract: No-till (NT) farming has been widely adopted to assist in reducing erosion, lowering fuel costs, conserving soil moisture and improving soil physical, chemical and biological characteristics. Improvements in soil characteristics are often driven by the greater soil organic matter accumulation (as measured by soil organic carbon (SOC)) in NT compared to conventional tillage (CT) farming systems. However, to fully understand the effect of NT it is important to understand temporal changes in SOC by monitoring over an extended period. We investigated the long-term effect of NT and stubble retention (SR) on changes in SOC and total soil nitrogen (STN) using results from an experiment that has been running for 50 years in a semi-arid subtropical region of north-eastern Australia. In this experiment, the effects of tillage (CT vs NT), residue management (stubble burning (SB) vs SR), and nitrogen (N) fertiliser (0 and 90 kg-N ha–1) were measured in a balanced factorial experiment on a Vertisol (Ustic Pellusert). The use of NT, SR and N fertiliser generally improved SOC (by up to 12.8%) and STN stocks (by up to 31.7%) in the 0–0.1 m layer relative to CT, SB and no N fertiliser, with the greatest stocks observed where all three treatments were used in combination. However, declines in SOC (up to 20%) and STN (up to 25%) occurred in all treatments over the course of the experiment, indicating that changes in management practices were unable to prevent a loss of soil organic matter over time in this farming system. However, the NT and SR treatments did lose less SOC than CT and SB treatments, and SR also reduced STN loss. The δ13C analysis of s les collected in 2008 and 2015 highlighted that crop residues have significantly contributed to SOC stocks at the site and that their contribution is increasing over time.
Nitrous oxide and methane emissions from soil are reduced following afforestation of pasture lands in three contrasting climatic zones
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR08151
Abstract: Land use change from agriculture to forestry offers potential opportunities for carbon (C) sequestration and thus partial mitigation of increasing levels of carbon dioxide (CO2) in the atmosphere. The effects of land use change of grazed pastures on in situ fluxes of nitrous oxide (N2O) and methane (CH4) from soil were examined across 3 forest types in Australian temperate, Mediterranean, and subtropical regions, using a network of paired pasture−forest sites, representing 3 key stages of forest stand development: establishment, canopy-closure, and mid to late rotation. During the 12-month study, soil temperature ranged from –6° to 40°C and total rainfall from 487 to 676 mm. Rates of N2O flux ranged between 1 and 100 μg/m2.h in pasture soils and from –5 to 50 μg/m2.h in forest soils magnitudes were generally similar across the 3 climate zones. Rates of CH4 flux varied from –1 to –50 μg/m2.h in forest soil and from +10 to –30 μg/m2.h in pasture soils CH4 flux was highest at the subtropics sites and lowest at the Mediterranean sites. In general, N2O emissions were lower, and CH4 consumption was higher, under forest than pasture soils, suggesting that land use change from pasture to forest can have a positive effect on mitigation of non-CO2 greenhouse gas (GHG) emissions from soil as stands become established. The information derived from this study can be used to improve the capacity of models for GHG accounting (e.g. FullCAM, which underpins Australia’s National Carbon Accounting System) to estimate N2O and CH4 fluxes resulting from land use change from pasture to forest in Australia. There is still, however, a need to test model outputs against continuous N2O and CH4 measurements over extended periods of time and across a range of sites with similar land use, to increase confidence in spatial and temporal estimates at regional levels.
The impact, identification and management of dispersive soils in rainfed cropping systems
Publisher: Wiley
Date: 12-2020
DOI: 10.1111/EJSS.13070
Abstract: Dispersive soils limit crop growth and significantly impact world food production. Although numerous reviews have examined soil dispersion, many focus on irrigated systems and fail to differentiate the approaches required for rainfed agriculture. This review seeks to fill this gap by focusing on the impact, identification and management of dispersive soils in rainfed areas. Dispersive soils can have large impacts on crop production because of their adverse physical, chemical and biological effects, with this impact particularly large in rainfed systems where irrigation water is unavailable to supplement crop water supply and assist with amelioration. However, the identification of these soils is challenging and tests that can reliably relate soil characteristics to crop performance are lacking. Recent work has found that first identifying consistently lower yielding locations (using yield mapping or proximal/remote sensing) and then using traditional soil testing to identify the potential cause/s of the yield loss may be a promising approach, although this requires refinement. Knowledge of the type of dispersive soil (e.g., saline/non‐saline, acidic/alkaline/neutral) and where constraints occur in the profile (surface or subsoil) must also be determined during identification as this will affect management approaches, particularly where multiple constraints need to be treated together to achieve yield increase. Improved understanding of how to economically use ameliorants and combine them to achieve maximum benefit in the presence of multiple constraints is needed. Greater appreciation of how to use agronomic management to improve crop growth in the presence of dispersive behaviour is also likely to increase profitability in rainfed systems where amelioration is often impractical or uneconomical. Dispersive soils are a major challenge for rainfed cropping, and so the refinement of our management approach can help improve profitability and productivity. Dispersive soils limit crop growth and significantly impact world food production We examine the impact, identification and management of dispersive soils in rainfed agriculture Improvements in the identification of dispersive soils are required to improve management Refinement of ameliorant use and agronomic management will improve profitability and productivity
Impact of 47 Years of No Tillage and Stubble Retention on Soil Aggregation and Carbon Distribution in a Vertisol
Publisher: Wiley
Date: 03-05-2017
DOI: 10.1002/LDR.2689
Soil nitrogen and nitrogen-use efficiency under long-term no-till practice
Publisher: Wiley
Date: 11-2011
Nitrification in a Vertisol subsoil and its relationship to the accumulation of ammonium-nitrogen at depth
Publisher: CSIRO Publishing
Date: 2002
DOI: 10.1071/SR01087
Abstract: Unusually high concentrations of ammonium have been observed in a Vertisol below 1 m depth in south-east Queensland. This study investigated the possibility that an absence of nitrification is allowing this ammonium to accumulate and persist over time, and examined the soil environmental characteristics that may be responsible for limiting nitrifying organisms. The possibility that anaerobiosis, soil acidity, soil salinity, low organic carbon concentrations, and/or an absence of active nitrifying microorganisms were responsible for limiting nitrification was examined in laboratory and field studies. The presence/absence of anaerobic conditions was determined qualitatively using a field test to give an indication of electron lability. In addition, an incubation study was conducted and soil environmental conditions were improved for nitrifying organisms by adjusting the pH from 4.4 to 7, adjusting the electrical conductivity from 1.6 to 0.5 dS/m, amending with a soluble carbon substrate at a rate of 500 mg/kg, and using microorganisms from the surface horizon to inoculate to the subsoil. Over a 180-day period no nitrification was detected in the control s les from the incubation study, indicating that an extremely low rate of nitrification is likely to be responsible for allowing ammonium to accumulate in this soil. Analysis of the effect of soil environmental conditions on nitrification revealed that anaerobic conditions did not exist at depth and that pH, EC, organic carbon, and inoculation treatments added in isolation had no effect on nitrification. However, when inoculum was added to the soil in combination with pH, a significant increase in nitrification was observed, and the greatest amount of nitrification was observed when inoculum, pH, and EC treatments were added in combination. It was concluded that the reason for the low rate of nitrification in this soil is primarily the absence of a significant population of active nitrifying microorganisms, which may have been unable to colonise the subsoil environment due to its acidic, and to a lesser extent, its saline environment.
Effects of urea formulations, application rates and crop residue retention on N2O emissions from sugarcane fields in Australia
Publisher: Elsevier BV
Date: 2016
Land use affects temperature sensitivity of soil organic carbon decomposition in macroaggregates but not in bulk soils in subtropical Oxisols of Queensland, Australia
Publisher: Elsevier BV
Date: 04-2020
Organic carbon and total nitrogen stocks in a Vertisol following 40 years of no-tillage, crop residue retention and nitrogen fertilisation
Publisher: Elsevier BV
Date: 04-2011
A study over 33 years shows that carbon and nitrogen stocks in a subtropical soil are increasing under native vegetation in a changing climate
Publisher: Elsevier BV
Date: 06-2021
Carbon inventory for a cereal cropping system under contrasting tillage, nitrogen fertilisation and stubble management practices
Publisher: Elsevier BV
Date: 12-2006
Total soil organic matter and its labile pools following mulga (Acacia aneura) clearing for pasture development and cropping. 2. Total and labile nitrogen
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/SR04076
Abstract: Mulga (Acacia aneura) woodlands and open forests occupy about 150 Mha in Australia, and originally occupied 11.2 Mha in Queensland. Substantial areas (1.3 Mha) of the mulga vegetation have been cleared in Queensland, mostly for pasture production, but some areas are also used for cereal cropping. Twenty years after mulga clearing we found a significant loss of total soil organic C (28–35% from the 0–0.05 m depth) and light fraction C ( % from the 0–1 m depth) from soil under pasture and cropping at a site in southern Queensland. We report here the changes in soil N and labile N pools in a paired-site study following conversion of mulga to buffel pasture (Cenchrus ciliaris) and cereal (mostly wheat) cropping for more than 20 years. Conversion from mulga forest to pasture and cultivation resulted in greater losses of soil N than organic C in the top 0.1 m depths. As a result, C/N ratios in soil under both pasture and cropping were higher than soil under mulga, indicating a decline in soil organic matter quality after mulga clearing. Although land-use change had no significant effect on 15N natural abundance (δ15N) values of total soil N down to a depth of 1 m, δ15N values of wheat tops and roots indicated that the primary source of N under cropping was soil organic N, while that of buffel pasture was a mixed source of soil N and decomposed litter and root N. Light fraction N ( .6 Mg/m3) declined by 60–70% throughout the 1 m soil profile under pasture and cropping, but it was 15N-enriched in these 2 land-use systems. The δ15N values of mulga phyllodes, twigs, and fine roots, indicated an input of atmospheric fixed N2 that was estimated to be about 25 kg N/ha.year. However, the source and magnitude of this N resource needs to be confirmed. Soil N losses were estimated to be 12 kg N/ha.year under pasture and 17 kg N/ha.year under cropping over a 20-year period. These findings raise the issue of the long-term sustainable use of cleared mulga areas for pasture and/or cropping. The labile C and N pools and N mineralised also declined, which would have an immediate adverse effect on soil fertility and plant productivity of cleared Mulga Lands, as well as reducing their potential as a soil sink for greenhouse gases.
Soil carbon, nitrogen, and biotic properties after long-term no-till and nitrogen fertilization in a subtropical Vertisol
Publisher: Elsevier BV
Date: 03-2023
Crop residues and fertilizer nitrogen influence residue decomposition and nitrous oxide emission from a Vertisol
Publisher: Springer Science and Business Media LLC
Date: 04-09-2010
13C-NMR analysis of decomposing litter and fine roots in the semi-arid Mulga Lands of southern Queensland
Publisher: Elsevier BV
Date: 05-2007
Carbon storage in a Ferrosol under subtropical rainforest, tree plantations, and pasture is linked to soil aggregation
Publisher: CSIRO Publishing
Date: 2009
DOI: 10.1071/SR08162
Abstract: Soil is a large sink for carbon (C), with the potential to significantly reduce the net increase in atmospheric CO2 concentration. However, we previously showed that subtropical tree plantations store less C into long-term soil pools than rainforest or pasture. To explore reasons for differences in C storage between different land-use systems, we examined the relationships between soil aggregation, iron and aluminium oxide and hydroxide content, and soil organic C (SOC) under exotic C4 pasture (Pennisetum clandestinum), native hoop pine (Araucaria cunninghamii) plantations, and rainforest. We measured SOC concentrations of water-stable and fully dispersed aggregates to assess the location of soil C. Concentrations of dithionite- and oxalate-extractable iron and aluminium were also determined to assess their role in SOC sequestration. Soil under rainforest and pasture contained more C in intra-aggregate particulate organic matter (iPOM, μm) than hoop pine plantations, indicating that in rainforest and pasture, greater stabilisation of SOC occurred via soil aggregation. SOC was not significantly correlated with dithionite- and oxalate-extractable Fe and Al in these systems, indicating that sorption sites of Fe and Al oxides and hydroxides were saturated. We concluded that soil C under rainforest and pasture is stabilised by incorporation within soil aggregates, which results in greater storage of C in soil under pasture than plantations following land-use change. The reduced storage of C as iPOM in plantation soil contributes to the negative soil C budget of plantations compared with rainforest and pasture, even 63 years after establishment. The results have relevance for CO2 mitigation schemes based on tree plantations.
Molecular complexity and diversity of persistent soil organic matter
Publisher: Elsevier BV
Date: 09-2023
50 years of continuous no-tillage, stubble retention and nitrogen fertilization enhanced macro-aggregate formation and stabilisation in a Vertisol
Publisher: Elsevier BV
Date: 10-2021
Management of the major chemical soil constraints affecting yields in the grain growing region of Queensland and New South Wales, Australia – a review
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR18233
Abstract: In the grain growing region of Queensland and New South Wales, Australia, crop production occurs predominantly under semiarid, rainfed conditions. Vertosols dominate the soils used and many are prone to structural problems. In this region, providing that crop nutrition is adequate, optimising yield is largely dependent on maximising the infiltration, storage and plant use of soil water. Soil constraints such as sodicity, salinity, acidity, subsoil compaction and surface sealing can limit these processes, leading to high yield losses. This review examines management options to treat these constraints, focusing on management where multiple constraints exist, and where these occur in the subsoil. The main strategies reviewed include (a) use of gypsum to treat sodicity and lime to treat acidity, which can lead to yield increases of & % in some circumstances, (b) cultivation or deep ripping to break up compacted sodic layers and surface seals, (c) incorporating soil organic matter to improve conditions for plant growth and (d) selecting species, cultivars and management practices most appropriate for constrained sites. Future research must be directed to improving the profitability of ameliorant use for sodicity by increasing our understanding of how to identify soils responsive to ameliorants, and which combination of ameliorants will be cost effective when sodicity occurs in combination with other constraints. In addition, research needs to target ways to economically apply ameliorants in subsoil environments, and better identify which crop species or cultivars are productive on constrained sites, particularly those with multiple constraints.
Relationships of soil respiration to microbial biomass, substrate availability and clay content
Publisher: Elsevier BV
Date: 02-2003
Nitrate ammonification and its relationship to the accumulation of ammonium in a Vertisol subsoil
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/SR02100
Abstract: High concentrations of ammonium (up to 270 kg N/ha) have been observed in a Vertisol soil below 1 m depth near Warra in south-east Queensland. This study examined the possibility that increased water movement into the subsoil after the removal of native vegetation, and a subsequent increase in periods of waterlogging, could have triggered nitrate ammonification and be responsible for the production of ammonium. Two incubation experiments were conducted to test this hypothesis. The first involved the incubation of repacked cores that had been amended with 30 mg N/kg of 5 atom% 15N nitrate under low oxygen conditions for a period of 360 days. Over this time period the 15N enrichment of the exchangeable ammonium fraction was monitored in order to detect any reduction of nitrate to ammonium. The second experiment involved the incubation of soil amended with 30 mg N/kg of 5 atom% 15N nitrate under waterlogged and low oxygen conditions for 75 days. During this period the redox potential of the soil was monitored using a field test to determine if reducing conditions would develop in this soil over a period of waterlogging, combined with the monitoring of any nitrate reduction to ammonium. The results of these experiments indicated that a small amount of nitrate ammonification ( .1 mg N/kg) could be observed in the Warra subsoil, but that unless the rate of reduction were to significantly increase with time, this could not account for the accumulation of ammonium observed in the field. The environmental conditions that would make either dissimilatory or abiotic nitrate ammonification favourable were not observed to develop. Consequently, it has been concluded that the observed nitrate ammonification occurred via an assimilatory pathway. Due to the low rate of microbial activity in this subsoil it is considered unlikely that this process was responsible for the subsoil ammonium accumulation at Warra.
The legacy of cropping history reduces the recovery of soil carbon and nitrogen after conversion from continuous cropping to permanent pasture
Publisher: Elsevier BV
Date: 2016
Greenhouse gas fluxes from an Australian subtropical cropland under long‐term contrasting management regimes
Publisher: Wiley
Date: 06-2011
Efficient Nitrogen and Water Management for the Soybean–Wheat System of Madhya Pradesh, Central India, Assessed Using APSIM Model
Publisher: Springer Science and Business Media LLC
Date: 18-10-2014
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.
Nutrient Mass Balances and Leaching Losses from a Farmyard Manure Pit in Madhya Pradesh
Publisher: Diva Enterprises Private Limited
Date: 2015
Piggery pond sludge as a nitrogen source for crops 2. Assay of wet and stockpiled piggery pond sludge by successive cereal crops or direct measurement of soil available N
Publisher: CSIRO Publishing
Date: 2005
DOI: 10.1071/AR04230
Abstract: The appropriate use of wastes is a significant issue for the pig industry due to increasing pressure from regulatory authorities to protect the environment from pollution. Nitrogen contained in piggery pond sludge (PPS) is a potential source of supplementary nutrient for crop production. Nitrogen contribution following the application of PPS to soil was obtained from 2 field experiments on the Darling Downs in southern Queensland on contrasting soil types, a cracking clay (Vertosol) and a hardsetting sandy loam (Sodosol), and related to potentially mineralisable N from laboratory incubations conducted under controlled conditions and NO3– accumulation in the field. Piggery pond sludge was applied as-collected (wet PPS) and following stockpiling to dry (stockpiled PPS). Soil NO3– levels increased with increased application rates of wet and stockpiled PPS. Supplementary N supply from PPS estimated by fertiliser equivalence was generally unsatisfactory due to poor precision with this method, and also due to a high level of NO3– in the clay soil before the first assay crop. Also low recoveries of N by subsequent sorghum (Sorghum bicolor) and wheat (Triticum aestivum) assay crops at the 2 sites due to low in-crop rainfall in 1999 resulted in low apparent N availability. Over all, 29% (range 12–47%) of total N from the wet PPS and 19% (range 0–50%) from the stockpiled PPS were estimated to be plant-available N during the assay period. The high concentration of NO3- for the wet PPS application on sandy soil after the first assay crop (1998 barley, Hordeum vulgare) suggests that leaching of NO3– could be of concern when high rates of wet PPS are applied before infrequent periods of high precipitation, due primarily to the mineral N contained in wet PPS. Low yields, grain protein concentrations, and crop N uptake of the sorghum crop following the barley crop grown on the clay soil demonstrated a low residual value of N applied in PPS. NO3– in the sandy soil before sowing accounted for 79% of the variation in plant N uptake and was a better index than anaerobically mineralisable N (19% of variation explained). In clay soil, better prediction of crop N uptake was obtained when both anaerobically mineralisable N (39% of variation explained) and soil profile NO3– were used in combination (R2 = 0.49).
Using quantity/intensity relationships to assess the potential for ammonium leaching in a Vertosol
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/SR02061
Abstract: High concentrations of ammonium (up to 0.1 cmol/kg) have been observed below 1 m depth in a Vertosol soil near Warra in south-eastern Queensland. This study examined whether ammonium leaching could be responsible for the ammonium accumulation observed in the Warra soil. This was done by using quantity/intensity (Q/I) relationships to compare the ammonium retention capacity of the Warra soil with other similar soils throughout the region that did not contain elevated subsoil ammonium concentrations. Analysis of Q/I curves revealed that in the concentration range studied, the amount of ammonium retained on high affinity adsorption sites in all 3 soils was low, and the Warra soil was not significantly different from the other 2 soils. The ability of the soils to retain ammonium in the soil solution against leaching [i.e. their potential buffer capacity (PBC)] did differ between soils and was greatest at Warra. This indicates that at any one time the Warra soil holds more ammonium on the exchange complex and less in solution than the other soils examined. It was concluded that ammonium is no more likely to leach through the surface horizons of the Warra soil than the other soils examined. Indeed, the data indicated that the Warra soil probably has greater capacity to retain ammonium against leaching due to its greater PBC. Consequently, it is considered unlikely that leaching of ammonium has been a major contributor to the subsoil ammonium concentrations at Warra.
Nitrous oxide emission from Australian agricultural lands and mitigation options: a review
Publisher: CSIRO Publishing
Date: 2003
DOI: 10.1071/SR02064
Abstract: Increases in the concentrations of greenhouse gases, carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), and halocarbons in the atmosphere due to human activities are associated with global climate change. The concentration of N2O has increased by 16% since 1750. Although atmospheric concentration of N2O is much smaller (314 ppb in 1998) than of CO2 (365 ppm), its global warming potential (cumulative radiative forcing) is 296 times that of the latter in a 100-year time horizon. Currently, it contributes about 6% of the overall global warming effect but its contribution from the agricultural sector is about 16%. Of that, almost 80% of N2O is emitted from Australian agricultural lands, originating from N fertilisers (32%), soil disturbance (38%), and animal waste (30%). Nitrous oxide is primarily produced in soil by the activities of microorganisms during nitrification, and denitrification processes. The ratio of N2O to N2 production depends on oxygen supply or water-filled pore space, decomposable organic carbon, N substrate supply, temperature, and pH and salinity. N2O production from soil is sporadic both in time and space, and therefore, it is a challenge to scale up the measurements of N2O emission from a given location and time to regional and national levels.Estimates of N2O emissions from various agricultural systems vary widely. For ex le, in flooded rice in the Riverina Plains, N2O emissions ranged from 0.02% to 1.4% of fertiliser N applied, whereas in irrigated sugarcane crops, 15.4% of fertiliser was lost over a 4-day period. Nitrous oxide emissions from fertilised dairy pasture soils in Victoria range from 6 to 11 kg N2O-N/ha, whereas in arable cereal cropping, N2O emissions range from .01% to 9.9% of N fertiliser applications. Nitrous oxide emissions from soil nitrite and nitrates resulting from residual fertiliser and legumes are rarely studied but probably exceed those from fertilisers, due to frequent wetting and drying cycles over a longer period and larger area. In ley cropping systems, significant N2O losses could occur, from the accumulation of mainly nitrate-N, following mineralisation of organic N from legume-based pastures. Extensive grazed pastures and rangelands contribute annually about 0.2 kg N/ha as N2O (93 kg/ha per year CO2-equivalent). Tropical savannas probably contribute an order of magnitude more, including that from frequent fires. Unfertilised forestry systems may emit less but the fertilised plantations emit more N2O than the extensive grazed pastures. However, currently there are limited data to quantify N2O losses in systems under ley cropping, tropical savannas, and forestry in Australia. Overall, there is a need to examine the emission factors used in estimating national N2O emissions for ex le, 1.25% of fertiliser or animal-excreted N appearing as N2O (IPCC 1996). The primary consideration for mitigating N2O emissions from agricultural lands is to match the supply of mineral N (from fertiliser applications, legume-fixed N, organic matter, or manures) to its spatial and temporal needs by crops astures/trees. Thus, when appropriate, mineral N supply should be regulated through slow-release (urease and/or nitrification inhibitors, physical coatings, or high C/N ratio materials) or split fertiliser application. Also, N use could be maximised by balancing other nutrient supplies to plants. Moreover, non-legume cover crops could be used to take up residual mineral N following N-fertilised main crops or mineral N accumulated following legume leys. For manure management, the most effective practice is the early application and immediate incorporation of manure into soil to reduce direct N2O emissions as well as secondary emissions from deposition of ammonia volatilised from manure and urine.Current models such as DNDC and DAYCENT can be used to simulate N2O production from soil after parameterisation with the local data, and appropriate modification and verification against the measured N2O emissions under different management practices.In summary, improved estimates of N2O emission from agricultural lands and mitigation options can be achieved by a directed national research program that is of considerable duration, covers s ling season and climate, and combines different techniques (chamber and micrometeorological) using high precision analytical instruments and simulation modelling, under a range of strategic activities in the agriculture sector.
Effect of fresh green waste and green waste compost on mineral nitrogen, nitrous oxide and carbon dioxide from a Vertisol
Publisher: Elsevier BV
Date: 08-2011
DOI: 10.1016/J.WASMAN.2011.03.019
Abstract: Incorporation of organic waste amendments to a horticultural soil, prior to expected risk periods, could immobilise mineral N, ultimately reducing nitrogen (N) losses as nitrous oxide (N(2)O) and leaching. Two organic waste amendments were selected, a fresh green waste (FGW) and green waste compost (GWC) as they had suitable biochemical attributes to initiate N immobilisation into the microbial biomass and organic N forms. These characteristics include a high C:N ratio (FGW 44:1, GWC 35:1), low total N ( 14%). Both products were applied at 3t C/ha to a high N (plus N fertiliser) or low N (no fertiliser addition) Vertisol soil in PVC columns. Cumulative N(2)O production over the 28 day incubation from the control soil was 1.5mg/N(2)O/m(2), and 11mg/N(2)O/m(2) from the control+N. The N(2)O emission decreased with GWC addition (P<0.05) for the high N soil, reducing cumulative N(2)O emissions by 38% by the conclusion of the incubation. Analysis of mineral N concentrations at 7, 14 and 28 days identified that both FGW and GWC induced microbial immobilisation of N in the first 7 days of incubation regardless of whether the soil environment was initially high or low in N with the FGW immobilising up to 30% of available N. It is likely that the reduced mineral N due to N immobilisation led to a reduced substrate for N(2)O production during the first week of the trial, when soil N(2)O emissions peaked. An additional finding was that FGW+N did not decrease cumulative N(2)O emissions compared to the control+N, potentially due to the fact that it stimulated microbial respiration resulting in anaerobic micro sites in the soil and ultimately N(2)O production via denitrification. Therefore, both materials could be used as post harvest amendments in horticulture to minimise N loss through nitrate-N leaching in the risk periods between crop rotations. The mature GWC has potential to reduce N(2)O, an important greenhouse gas.
Responses of nitrous oxide emissions from crop rotation systems to four projected future climate change scenarios on a black Vertosol in subtropical Australia
Publisher: Springer Science and Business Media LLC
Date: 04-05-2017
Farmer Involvement in the Development and Adoption of Improved Nutrient Management Technologies Using the Mother–Baby Trial Approach in Vertisols
Publisher: Springer Science and Business Media LLC
Date: 17-09-2013
Reforestation of agricultural land in the tropics: The relative contribution of soil, living biomass and debris pools to carbon sequestration
Publisher: Elsevier BV
Date: 02-2019
DOI: 10.1016/J.SCITOTENV.2018.08.351
Abstract: Tropical regions of the world experience high rates of land-use change and this has a major influence on terrestrial carbon (C) pools and the global C cycle. We assessed land-use change from agriculture to reforested plantings (with endemic species), up to 33 years of age, using 10 paired sites in the wet tropics, Australia. We determined the impacts on 0-50 cm below-ground C (soil organic C (SOC), charcoal C, humic organic C, particulate organic C, resistant organic C), C stored in roots (fine and coarse), C stored in living above-ground biomass and debris C pools. Reforested areas accumulated ecosystem C at a rate of 7.4 Mg ha
Ecological stoichiometry controls the transformation and retention of plant-derived organic matter to humus in response to nitrogen fertilisation
Publisher: Elsevier BV
Date: 08-2016
Soil warming and liming impacts on the recovery of 15 N in an acidic soil under soybean cropping
Publisher: Wiley
Date: 23-02-2016
The effect of salinity on plant-available water
Publisher: Springer Science and Business Media LLC
Date: 17-06-2017
Soil organic matter is stabilized by organo-mineral associations through two key processes: The role of the carbon to nitrogen ratio
Publisher: Elsevier BV
Date: 2020
Greenhouse gas implications of leucaena-based pastures. Can we develop an emissions reduction methodology for the beef industry?
Publisher: Centro Internacional de Agricultura Tropical
Date: 03-09-2019
Abstract: Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.The perennial legume leucaena (Leucaena leucocephala) is grown across the subtropics for a variety of purposes including livestock fodder. Livestock in Australia emit a significant proportion of the methane produced by the agriculture sector and there is increasing pressure to decrease emissions from beef cattle production systems. In addition to direct productivity gains for livestock, leucaena has been shown to lower enteric methane production, suggesting an opportunity for emissions mitigation and Commonwealth Emissions Reduction Fund (ERF) methodology development, where leucaena browse is adopted for high value beef production. Determining the proportion of leucaena in the diet may be one of the more challenging aspects in attributing mitigation. Current enteric emission relationships for cattle consuming mixed grass-leucaena diets are based on intensive respiration chamber work. Herd-scale methane flux has also been determined using open path laser methodologies and may be used to validate an on-farm herd-scale methodology for leucaena feeding systems. The methodology should also address increased potential for soil organic carbon storage by leucaena grazing systems, and changes in nitrous oxide production. This paper outlines the background, justification, eligibility requirements and potential gaps in research for an emissions quantification protocol that will lead to the adoption of a leucaena methodology by the Australian beef industry. Development of a methodology would be supported by research conducted in Australia.
Combined Application of Lime and a Nitrification Inhibitor (3,4-Dimethylpyrazole Phosphate) Markedly Decreased Nitrous Oxide Emissions from an Acid Soil
Publisher: MDPI AG
Date: 27-04-2022
Abstract: High nitrous oxide (N2O) emissions (2–10% of fertiliser N) were observed previously from acid soils cropped with sugarcane (Saccharum officinarum) in Australia. We assessed the impact of lime, a nitrification inhibitor (NI, as 3,4-dimethylpyrazole phosphate, DMPP), and copper (Cu) on N2O emissions from an acid sugarcane soil in a laboratory experiment using (1) urea (U), (2) U + DMPP, (3) U + CuSO4.5H2O (U + Cu), and (4) U + DMPP + Cu. The treatments were applied to both an un-limed soil (pH 5.1) and a limed soil (pH 6.9) and incubated at 25 °C and 55% water holding capacity (WHC) for 28 d, and then increased to 90% WHC for another 8 d to favour denitrification. At 55% WHC, both the addition of the NI (U + DMPP) and the liming of the acid soil significantly decreased cumulative N2O emissions, due to significantly lower net nitrifications. Liming and DMPP decreased N2O emissions by 79% and 90%, respectively. However, where lime and DMPP were applied together, N2O emissions decreased by 94% compared to those in the un-limed (acid) U-treated soil. In contrast, the addition of Cu and the increase in water content to 90% WHC had no significant effect on N2O emissions. Therefore, the combined use of lime and DMPP provides the best option to decrease N2O emissions from the acid soil.
Quantitative Measurement of Organic Carbon in Mine Wastes: Methods Comparison for Inorganic Carbon Removal and Organic Carbon Recovery
Publisher: Informa UK Limited
Date: 08-12-2014
Global changes in soil stocks of carbon, nitrogen, phosphorus, and sulphur as influenced by long‐term agricultural production
Publisher: Wiley
Date: 11-10-2016
DOI: 10.1111/GCB.13513
Abstract: Quantifying changes in stocks of C, N, P, and S in agricultural soils is important not only for managing these soils sustainably as required to feed a growing human population, but for C and N, they are also important for understanding fluxes of greenhouse gases from the soil environment. In a global meta-analysis, 102 studies were examined to investigate changes in soil stocks of organic C, total N, total P, and total S associated with long-term land-use changes. Conversion of native vegetation to cropping resulted in substantial losses of C (-1.6 kg m
Differential Gene Expression in the Model Actinomycete Streptomyces coelicolor A3(2) Supports Nitrogen Mining Dependent on the Plant Carbon to Nitrogen Ratio
Publisher: MDPI AG
Date: 06-12-2018
DOI: 10.3390/AGRICULTURE8120192
Abstract: Nitrogen mining is the process whereby microbial communities catabolise recalcitrant long-term organic matter (OM) to meet nutritional requirements that are not ensured by labile OM. Microbial degradation of recalcitrant OM impacts soil fertility and contributes to greenhouse gas emissions in agricultural systems. Here we conducted a transcriptomics study to track differential gene expression in the model soil Actinomycete Streptomyces coelicolor A3(2) during the decomposition of mung bean (Vigna radiata L.) and wheat (Triticum aestivum L.) residues of relatively low and high carbon-to-nitrogen (C:N) ratios (17.3 and 35.7, respectively) at 1, 7, and 14 days of incubation. A negative binomial general linear model showed that plant variety predominantly affected transcription (p 0.001), although time of incubation also had an effect (p = 0.01). In the high C:N ratio treatment, the expression of cellulases, chitinase, N-acetylglucosaminidase, secreted peptidases, and mineral nitrogen (N) metabolism were increased after 24 h. The low C:N ratio treatment demonstrated preferential expression of glutamate dehydrogenase, transporters involved in glutamate uptake and glycolysis, indicating more efficient N and carbon (C) assimilation. After 14 days, the low C:N ratio treatment showed increased transcription of extracellular enzymes, glutamate dehydrogenase, and glutamate transport. These results show an important role for added plant organic N content in determining when the transcription of genes associated with N mining occurs.
High subsoil chloride concentrations reduce soil water extraction and crop yield on Vertosols in north-eastern Australia
Publisher: CSIRO Publishing
Date: 2008
DOI: 10.1071/AR07192
Abstract: Salinity, sodicity, acidity, and phytotoxic levels of chloride (Cl) in subsoils are major constraints to crop production in many soils of north-eastern Australia because they reduce the ability of crop roots to extract water and nutrients from the soil. The complex interactions and correlations among soil properties result in multi-colinearity between soil properties and crop yield that makes it difficult to determine which constraint is the major limitation. We used ridge-regression analysis to overcome colinearity to evaluate the contribution of soil factors and water supply to the variation in the yields of 5 winter crops on soils with various levels and combinations of subsoil constraints in the region. Subsoil constraints measured were soil Cl, electrical conductivity of the saturation extract (ECse), and exchangeable sodium percentage (ESP). The ridge regression procedure selected several of the variables used in a descriptive model, which included in-crop rainfall, plant-available soil water at sowing in the 0.90–1.10 m soil layer, and soil Cl in the 0.90–1.10 m soil layer, and accounted for 77–85% of the variation in the grain yields of the 5 winter crops. Inclusion of ESP of the top soil (0.0–0.10 m soil layer) marginally increased the descriptive capability of the models for bread wheat, barley and durum wheat. Subsoil Cl concentration was found to be an effective substitute for subsoil water extraction. The estimates of the critical levels of subsoil Cl for a 10% reduction in the grain yield were 492 mg cl/kg for chickpea, 662 mg Cl/kg for durum wheat, 854 mg Cl/kg for bread wheat, 980 mg Cl/kg for canola, and 1012 mg Cl/kg for barley, thus suggesting that chickpea and durum wheat were more sensitive to subsoil Cl than bread wheat, barley, and canola.
Soil organic carbon and nitrogen sequestration and turnover in aggregates under subtropical leucaena-grass pastures
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/SR18016
Abstract: Stabilisation and protection of soil organic carbon (SOC) in macroaggregates and microaggregates represents an important mechanism for the sequestration of SOC. Legume-based grass pastures have the potential to contribute to aggregate formation and stabilisation, thereby leading to SOC sequestration. However, there is limited research on the C and N dynamics of soil organic matter (SOM) fractions in deep-rooted legume leucaena (Leucaena leucocephala)–grass pastures. We assessed the potential of leucaena to sequester carbon (C) and nitrogen (N) in soil aggregates by estimating the origin, quantity and distribution in the soil profile. We utilised a chronosequence (0–40 years) of seasonally grazed leucaena stands (3–6 m rows), which were s led to a depth of 0.3 m at 0.1-m intervals. The soil was wet-sieved for different aggregate sizes (large macroaggregates, µm small macroaggregates, 250–2000 µm microaggregates, 53–250 µm and µm), including occluded particulate organic matter (oPOM) within macroaggregates ( µm), and then analysed for organic C, N and δ13C and δ15N. Leucaena promoted aggregation, which increased with the age of the leucaena stands, and in particular the formation of large macroaggregates compared with grass in the upper 0.2 m. Macroaggregates contained a greater SOC stock than microaggregates, principally as a function of the soil mass distribution. The oPOM-C and -N concentrations were highest in macroaggregates at all depths. The acid nonhydrolysable C and N distribution (recalcitrant SOM) provided no clear distinction in stabilisation of SOM between pastures. Leucaena- and possibly other legume-based grass pastures have potential to sequester SOC through stabilisation and protection of oPOM within macroaggregates in soil.
Functional Relationships of Soil Acidification, Liming, and Greenhouse Gas Flux
Publisher: Elsevier
Date: 2016
The effect of pasture utilization rate on stocks of soil organic carbon and total nitrogen in a semi-arid tropical grassland
Publisher: Elsevier BV
Date: 10-2014
Subsoil constraints to grain production in the cropping soils of the north-eastern region of Australia: an overview
Publisher: CSIRO Publishing
Date: 2006
DOI: 10.1071/EA04079
Abstract: In dryland agricultural systems of the subtropical, semi-arid region of north-eastern Australia, water is the most limiting resource. Crop productivity depends on the efficient use of rainfall and available water stored in the soil during fallow. Agronomic management practices including a period of fallow, stubble retention, and reduced tillage enhance reserves of soil water. However, access to stored water in these soils may be restricted by the presence of growth-limiting conditions in the rooting zone of the crop. These have been termed as subsoil constraints. Subsoil constraints may include compacted or gravel layers (physical), sodicity, salinity, acidity, nutrient deficiencies, presence of toxic elements (chemical) and low microbial activity (biological). Several of these constraints may occur together in some soils. Farmers have often not been able to obtain the potential yield determined by their prevailing climatic conditions in the marginal rainfall areas of the northern grains region. In the past, the adoption of soil management practices had been largely restricted to the top 100 mm soil layer. Exploitation of the subsoil as a source of water and nutrients has largely been overlooked. The key towards realising potential yields would be to gain better understanding of subsoils and their limitations, then develop options to manage them practically and economically. Due to the complex nature of the causal factors of these constraints, efforts are required for a combination of management approaches rather than in idual options, with the aim to combat these constraints for sustainable crop production, managing natural resources and avoiding environmental damage.
Effect of soil aggregate size and long-term contrasting tillage, stubble and nitrogen management regimes on CO2 fluxes from a Vertisol
Publisher: Elsevier BV
Date: 03-2019
Organic amendments and gypsum reduce dispersion and increase aggregation of two sodic Vertisols
Publisher: Elsevier BV
Date: 11-2022
Simulation of N2O emissions and mitigation options for rainfed wheat cropping on a Vertosol in the subtropics
Publisher: CSIRO Publishing
Date: 2013
DOI: 10.1071/SR12274
Abstract: The Water and Nitrogen Management Model (WNMM) was applied to simulate nitrous oxide (N2O) emissions from a wheat-cropped Vertosol under long-term management of no-till, crop residue retention, and nitrogen (N) fertiliser application in southern Queensland, Australia, from July 2006 to June 2009. For the simulation study, eight treatments of combinations of conventional tillage (CT) or no-till (NT), stubble burning (SB) or stubble retention (SR), and N fertiliser application at nil (0N) or 90 (90N) kg N/ha.year were used. The results indicated that WNMM satisfactorily simulated the soil water content of the topsoil, mineral N content of the entire soil profile (0–1.5 m), and N2O emissions from the soil under the eight treatments, compared with the corresponding field measurements. For simulating daily N2O emissions from soil, WNMM performed best for the treatment CT-SB-90N (R2 = 0.48, P 0.001 RMSE = 10.2 g N/ha.day) and worst for the treatment CT-SB-0N (R2 = 0.03, P = 0.174 RMSE = 1.2 g N/ha.day). WNMM predicted N2O emissions from the soil more accurately for the fertilised treatments (i.e. 90N v. 0N), and for the residue retained treatments (SR v. SB). To reduce N2O emissions from the no-till and fertilised treatments, three scenarios were examined: application of nitrification inhibitor, application of controlled-release fertiliser, and deep placement of liquid fertiliser (UAN32). Only the deep placement of UAN32 below the 35 cm depth was effective, and could reduce the N2O emissions from the soil by almost 40%.
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