@article{VanSwieten2013,
title = {Pyrolysing poultry litter reduces N_{2}O and CO_{2} fluxes},
author = { L van Zwieten and S.W Kimber and S.G Morris and B.P Singh and P. R. Grace and C Scheer and J Rust and A Downie and A. Cowie},
doi = {10.1016/j.scitotenv.2013.02.054},
year = {2013},
date = {2013-11-01},
journal = {Science of the Total Environment},
volume = {465},
pages = {279-287},
abstract = {Application of poultry litter (PL) to soil can lead to substantial nitrous oxide (N_{2}O) emissions due to the co-application of labile carbon (C) and nitrogen (N). Slow pyrolysis of PL to produce biochar may mitigate N_{2}O emissions from this source, whilst still providing agronomic benefits. In a corn crop on ferrosol with similarly matched available N inputs of ca. 116 kg N/ha, PL-biochar plus urea emitted significantly less N_{2}O (1.5 kg N_{2}O–N/ha) compared to raw PL at 4.9 kg N_{2}O–N/ha. Urea amendment without the PL-biochar emitted 1.2 kg N_{2}O–N/ha, and the PL-biochar alone emitted only 0.35 kg N_{2}O–N/ha. Both PL and PL-biochar resulted in similar corn yields and total N uptake which was significantly greater than for urea alone. Using stable isotope methodology, the majority (~ 80%) of N_{2}O emissions were shown to be from non-urea sources. Amendment with raw PL significantly increased C mineralisation and the quantity of permanganate oxidisable organic C. The low molar H/C (0.49) and O/C (0.16) ratios of the PL-biochar suggest its higher stability in soil than raw PL. The PL-biochar also had higher P and K fertiliser value than raw PL. This study suggests that PL-biochar is a valuable soil amendment with the potential to significantly reduce emissions of soil greenhouse gases compared to the raw product. Contrary to other studies, PL-biochar incorporated to 100 mm did not reduce N_{2}O emissions from surface applied urea, which suggests that further field evaluation of biochar impacts, and methods of application of both biochar and fertiliser, are needed.},
keywords = {Science of the Total Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Lane2013,
title = {The essential parameters of a resource-based carrying capacity assessment model: an Australian case study},
author = { M Lane and L Dawes and P. R. Grace},
doi = {10.1016/j.ecolmodel.2013.10.006},
year = {2013},
date = {2013-10-04},
journal = {Ecological Modelling},
volume = {272},
pages = {220-231},
abstract = {Carrying capacity assessments model a population's potential self-sufficiency. A crucial first step in the development of such modelling is to examine the basic resource-based parameters defining the population's production and consumption habits. These parameters include basic human needs such as food, water, shelter and energy together with climatic, environmental and behavioural characteristics. Each of these parameters imparts land-usage requirements in different ways and varied degrees so their incorporation into carrying capacity modelling also differs. Given that the availability and values of production parameters may differ between locations, no two carrying capacity models are likely to be exactly alike. However, the essential parameters themselves can remain consistent so one example, the Carrying Capacity Dashboard, is offered as a case study to highlight one way in which these parameters are utilised. While examples exist of findings made from carrying capacity assessment modelling, to date, guidelines for replication of such studies in other regions and scales have largely been overlooked. This paper addresses such shortcomings by describing a process for the inclusion and calibration of the most important resource-based parameters in a way that could be repeated elsewhere.},
keywords = {Ecological Modelling},
pubstate = {published},
tppubtype = {article}
}

@article{Rowlings2013,
title = {Influence of nitrogen fertiliser application and timing on greenhouse gas emissions from a lychee (Litchi chinensis) orchard in humid subtropical Australia},
author = {D. W. Rowlings and P. R. Grace and C Scheer and R. Kiese},
doi = {10.1016/j.agee.2013.08.013},
year = {2013},
date = {2013-08-06},
journal = {Agriculture, Ecosystems and Environment},
volume = {179},
pages = {168-178},
abstract = {"Nitrous oxide emissions from intensive, fertilised agricultural systems have been identified as significant contributors to both Australia's and the global greenhouse gas (GHG) budget. This is expected to increase as rates of agriculture intensification and land use change accelerate to support population growth and food production. Limited data exists on N_{2}O trace gas fluxes from subtropical or tropical tree cropping soils critical for the development of effective mitigation strategies. This study aimed to quantify GHG emissions over two consecutive years (March 2007 to March 2009) from a 30 year (lychee) orchard in the humid subtropical region of Australia. GHG fluxes were measured using a combination of high temporal resolution automated sampling and manually sampled chambers. No fertiliser was added to the plots during the 2007 measurement season. A split application of nitrogen fertiliser (urea) was added at the rate of 265 kg N ha^{−1} during the autumn and spring of 2008. Emissions of N_{2}O were influenced by rainfall events and seasonal temperatures during 2007 and the fertilisation events in 2008. Annual N_{2}O emissions from the lychee canopy increased from 1.7 kg N_{2}O–N ha^{−1} yr^{−1} for 2007, to 7.6 kg N_{2}O–N ha^{−1} yr^{−1} following fertiliser application in 2008. This represented an emission factor of 1.56%, corrected for background emissions. The timing of the split application was found to be critical to N_{2}O emissions, with over twice as much lost following an application in spring (2.44%) compared to autumn (EF: 1.10%). This research suggests that avoiding fertiliser application during the hot and moist spring/summer period can reduce N_{2}O losses without compromising yields."},
keywords = {Agriculture, Ecosystems and Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Barton2013,
title = {Is liming soil a strategy for mitigating nitrous oxide emissions from semi-arid soils?},
author = {Louise Barton and D.B. Gleeson and L.D. Maccarone and L.P. Zúñiga and D.V. Murphy},
doi = {10.1016/j.soilbio.2013.02.014},
year = {2013},
date = {2013-07-01},
journal = {Soil Biology & Biochemistry},
volume = {62},
pages = {28–35},
abstract = {Nitrous oxide (N_{2}O) emissions in semi-arid regions are often greater following summer rainfall events when the soil is fallow, than in response to N fertiliser applications during crop growth. Nitrogen fertiliser management strategies are therefore likely to be ineffective at mitigating N_{2}O emissions from these cropped agricultural soils. Here we examined the influence of raising soil pH on N_{2}O emissions, nitrification rates, and both nitrifier and denitrifier populations following simulated summer rainfall events. The soil pH was raised by applying lime to a field site 12 months before conducting the laboratory experiment, resulting in soil of contrasting pH (4.21 or 6.34). Nitrous oxide emissions ranged from 0 when the soil was dry to 0.065 µg N_{2}O–N g dry soil-1 h-1 following soil wetting; which was attributed to both denitrification and nitrification. Increasing soil pH only decreased N_{2}O emissions when losses were associated with nitrification, and increased amoA gene copy numbers. We propose increasing soil pH as a strategy for decreasing soil N_{2}O emissions from acidic soils following summer rainfall in semi-arid regions when emissions result from nitrification.},
keywords = {Soil carbon in nitrous oxide emissions},
pubstate = {published},
tppubtype = {article}
}

@article{Huang2013,
title = {Spatial Prediction of N_{2}O Emissions in Pasture: A Bayesian Model Averaging Analysis},
author = { X Huang and P. R Grace and W Hu and D. W. Rowlings and K. Mengersen},
doi = {10.1371/journal.pone.0065039},
year = {2013},
date = {2013-06-04},
journal = {PLOS ONE},
volume = {8},
number = {6},
abstract = {Nitrous oxide (N_{2}O) is one of the greenhouse gases that can contribute to global warming. Spatial variability of N_{2}O can lead to large uncertainties in prediction. However, previous studies have often ignored the spatial dependency to quantify the N_{2}O – environmental factors relationships. Few researches have examined the impacts of various spatial correlation structures (e.g. independence, distance-based and neighbourhood based) on spatial prediction of N_{2}O emissions. This study aimed to assess the impact of three spatial correlation structures on spatial predictions and calibrate the spatial prediction using Bayesian model averaging (BMA) based on replicated, irregular point-referenced data. The data were measured in 17 chambers randomly placed across a 271 m^{2} field between October 2007 and September 2008 in the southeast of Australia. We used a Bayesian geostatistical model and a Bayesian spatial conditional autoregressive (CAR) model to investigate and accommodate spatial dependency, and to estimate the effects of environmental variables on N_{2}O emissions across the study site. We compared these with a Bayesian regression model with independent errors. The three approaches resulted in different derived maps of spatial prediction of N_{2}O emissions. We found that incorporating spatial dependency in the model not only substantially improved predictions of N_{2}O emission from soil, but also better quantified uncertainties of soil parameters in the study. The hybrid model structure obtained by BMA improved the accuracy of spatial prediction of N_{2}O emissions across this study region.},
keywords = {PLOS ONE},
pubstate = {published},
tppubtype = {article}
}

@article{Huang2013b,
title = {A flexible Bayesian model for describing temporal variability of N_{2}O emissions from an Australian pasture},
author = { X Huang and P. R. Grace and D. W. Rowlings and K. Mengersen},
doi = {10.1016/j.scitotenv.2013.03.013},
year = {2013},
date = {2013-06-01},
journal = {Science of the Total Environment},
volume = {454-455},
number = {5},
pages = {206-210},
abstract = {Soil-based emissions of nitrous oxide (N_{2}O), a well-known greenhouse gas, have been associated with changes in soil water-filled pore space (WFPS) and soil temperature in many previous studies. However, it is acknowledged that the environment–N_{2}O relationship is complex and still relatively poorly unknown. In this article, we employed a Bayesian model selection approach (Reversible jump Markov chain Monte Carlo) to develop a data-informed model of the relationship between daily N_{2}O emissions and daily WFPS and soil temperature measurements between March 2007 and February 2009 from a soil under pasture in Queensland, Australia, taking seasonal factors and time-lagged effects into account. The model indicates a very strong relationship between a hybrid seasonal structure and daily N_{2}O emission, with the latter substantially increased in summer. Given the other variables in the model, daily soil WFPS, lagged by a week, had a negative influence on daily N_{2}O; there was evidence of a nonlinear positive relationship between daily soil WFPS and daily N_{2}O emission; and daily soil temperature tended to have a linear positive relationship with daily N_{2}O emission when daily soil temperature was above a threshold of approximately 19 °C. We suggest that this flexible Bayesian modeling approach could facilitate greater understanding of the shape of the covariate-N_{2}O flux relation and detection of effect thresholds in the natural temporal variation of environmental variables on N_{2}O emission.},
keywords = {Science of the Total Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Harris2013,
title = {Can nitrogen fertiliser and nitrification inhibitor management influence N_{2}O losses from high rainfall cropping systems in South Eastern Australia?},
author = {Robert H. Harris and Sally J. Officer and Patricia A. Hill and Roger D. Armstrong and Kirsten M. Fogarty and Reto P. Zollinger and Andrew J. Phelan},
doi = {10.1007/s10705-013-9562-0},
issn = {1385-1314},
year = {2013},
date = {2013-05-17},
journal = {Nutrient Cycling in Agroecosystems},
volume = {95},
number = {2},
pages = {269-285},
abstract = {Nitrous oxide (N2O) is a potent greenhouse gas released from high rainfall cropping soils, but the role of management in its abatement remains unclear in these environments. To quantify the relative influence of management, nitrogen (N) fertiliser and soil nitrification inhibitor was applied to separate but paired raised bed and conventionally flat field experiments in south west Victoria, to measure emissions and income from wheat and canola planted 2 and 3 years after conversion from a long-term pasture. Management included four different rates of N fertiliser, top-dressed with and without the nitrification inhibitor Dicyandiamide (DCD), which was applied in solution to the soil in the second year of experimentation. Crop biomass, grain yield, soil mineral N, soil temperature and soil water and N2O flux were measured. Static chamber methodology was used to identify relative differences in N2O loss between management. In the second crop (wheat) following conversion, N2O losses were up to 72 % lower (P�.05) in the furrows, receiving the lower rate of N fertiliser compared with the highest rate, with less frequent reductions observed in the third crop (canola); losses of N2O from the beds was unaffected by N rate, perhaps from nitrate leakage into the adjacent furrow of the raised bed experiment. On the nearby flat experiment, nitrate leaching may have diminished the effects of N rate and DCD on N2O flux. Furthermore the extra N did not significantly increase grain yield in either the wheat or canola crops on both experiments. The application of DCD in the canola crop temporarily reduced (P�.05) N2O production by up to 84 % from the beds, 83 % in the adjacent furrows and 75 % on the flat experiment. Grain yield was not significantly (P�.001) affected however, canola income was reduced by $1407/ha and $1252/ha, compared with no addition of inhibitor on the respective bed and flat experiments. Although N2O fluxes are driven by environmental episodic events, management will play a role in N2O abatement. However, DCD currently appears economically unfeasible and matching N fertiliser supply to meet crop demand appears a better option for minimising N2O losses from high rainfall cropping systems.},
keywords = {Reducing emissions through improved nitrogen use efficiency},
pubstate = {published},
tppubtype = {article}
}

@article{Barton2013,
title = {Influence of crop rotation and liming on greenhouse gas emissions from a semi-arid soil},
author = {Louise Barton and Daviel V.Murphy and Klaus Butterbach-Bahl},
doi = {10.1016/j.agee.2013.01.003},
year = {2013},
date = {2013-03-01},
pages = {23 – 32},
abstract = {Semi-arid lands represent one fifth of the global land area but our understanding of greenhouse gas fluxes from these regions is poor. We investigated if inclusion of a grain legume and/or lime in a crop rotation altered greenhouse gas emissions from an acidic soil. Nitrous oxide (N_{2}O) and methane (CH_{4}) fluxes were measured from a rain-fed, cropped soil in a semi-arid region of Australia for two years on a sub-daily basis. The randomised-block design included two cropping rotations (lupin–wheat, wheat–wheat) by two liming treatments (0, 3.5 t ha-1) by three replicates. The lupin–wheat rotation only received N fertilizer during the wheat phase (20 kg N ha-1), while the wheat–wheat received 125 kg N ha-1 during the two year study. Fluxes were measured using soil chambers connected to a fully automated system that measured N_{2}O and CH_{4} by gas chromatography. Nitrous oxide fluxes were low (-1.4 to 9.2 g N_{2}O-N ha-1 day-1), and less than those reported for arable soils in temperate climates. Including a grain legume in the cropping rotation did not enhance soil N_{2}O; total N_{2}O losses were approximately 0.1 kg N_{2}O-N ha-1 after two years for both lupin–wheat and wheat–wheat rotations when averaged across liming treatment. Liming decreased cumulative N_{2}O emissions from the wheat–wheat rotation by 30% by lowering the contribution of N_{2}O emissions following summer–autumn rainfall events, but had no effect on N_{2}O emissions from the lupin–wheat rotation. Daily CH_{4} fluxes ranged from -14 to 5 g CH_{4}-C ha-1 day-1. Methane uptake after two years was lower from the wheat–wheat rotation (601 g CH_{4}-C ha-1) than from either lupin–wheat rotations (967 g CH_{4}-C ha-1), however liming the wheat–wheat rotation increased CH_{4} uptake (1078 g CH_{4}-C ha-1) to a value similar to the lupin–wheat rotation. Liming provides a strategy for lowering on-farm greenhouse gas emissions from N fertilised soils in semi-arid environments via decreased N_{2}O fluxes and increased CH_{4} uptake.},
note = {Agriculture, Ecosystems and Environment, 167 (2013) Pp. 23 – 32 Barton et al. 2013 (AGEE)},
keywords = {Soil carbon in nitrous oxide emissions},
pubstate = {published},
tppubtype = {article}
}

@article{Suter2013,
title = {Influence of urea fertiliser formulation, urease inhibitor and season on ammonia loss from ryegrass},
author = {Helen Suter and Humaira Sultana and Debra Turner and Rohan Davies and Charlie Walker and Deli Chen},
doi = {10.1007/s10705-013-9556-y},
year = {2013},
date = {2013-03-01},
journal = {Nutrient Cycling in Agroecosystems},
volume = {95},
number = {2},
abstract = {This paper reports the results of experiments to determine whether ammonia (NH3) loss can be reduced and nitrogen (N) use efficiency improved by using two relatively new commercial urea formulations rather than granular urea and urea ammonium nitrate. Four nitrogen treatments were applied at a rate of 40 kg N ha−1: granular urea, ‘Green Urea™ 14’ [containing 45.8 % N as urea and ‘Agrotain®’ (N-(n-butyl) thiophosphoric triamide) @ 5 L t−1 of urea as a urease inhibitor], ‘Nhance’, a fine particle spray [containing 46 % N as urea, ‘Agrotain’ @ 1 L t−1 of urea and gibberellic acid (applied at a rate of 10 g ha−1)] and urea ammonium nitrate in solution (UAN) surface applied. Ammonia loss was determined in autumn and spring using a micrometeorological method. In autumn, use of the Green Urea and Nhance reduced NH3 loss from the 30 % of applied N lost from the granular urea to 9 and 23 % respectively. Loss from all treatments in spring was very small (<2 % of applied N), because 4 mm of rain fell within 24 h of application onto an already wet site. The use of the Nhance and Green Urea instead of granular urea did not result in increased agronomic efficiency or recovery efficiency of the applied N, and this is most likely due to the presence of sufficient available N from both fertiliser application and the soil. A 15N study recovered 72.8 % of the applied N in the plants and soil, and showed that 30 % of the total N taken up by the plant was derived from the fertiliser, and 70 % from the soil. },
keywords = {Inhibitors for reducing emissions},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2012,
title = {Soil N_{2}O and CO_{2} emissions from cotton in Australia under varying irrigation management},
author = { C Scheer and P. R. Grace and D Rowlings and J. Payero},
doi = {10.1007/s10705-012-9547-4},
year = {2012},
date = {2012-12-15},
journal = {Nutrient Cycling in Agroecosystems},
volume = {95},
pages = {43-56},
abstract = {Irrigation is known to stimulate soil microbial carbon and nitrogen turnover and potentially the emissions of nitrous oxide (N_{2}O) and carbon dioxide (CO_{2}). We conducted a study to evaluate the effect of three different irrigation intensities on soil N_{2}O and CO_{2} fluxes and to determine if irrigation management can be used to mitigate N_{2}O emissions from irrigated cotton on black vertisols in South-Eastern Queensland, Australia. Fluxes were measured over the entire 2009/2010 cotton growing season with a fully automated chamber system that measured emissions on a sub-daily basis. Irrigation intensity had a significant effect on CO_{2} emission. More frequent irrigation stimulated soil respiration and seasonal CO_{2} fluxes ranged from 2.7 to 4.1 Mg-C ha^{−1} for the treatments with the lowest and highest irrigation frequency, respectively. N_{2}O emission happened episodic with highest emissions when heavy rainfall or irrigation coincided with elevated soil mineral N levels and seasonal emissions ranged from 0.80 to 1.07 kg N_{2}O-N ha^{−1} for the different treatments. Emission factors (EF = proportion of N fertilizer emitted as N_{2}O) over the cotton cropping season, uncorrected for background emissions, ranged from 0.40 to 0.53 % of total N applied for the different treatments. There was no significant effect of the different irrigation treatments on soil N_{2}O fluxes because highest emission happened in all treatments following heavy rainfall caused by a series of summer thunderstorms which overrode the effect of the irrigation treatment. However, higher irrigation intensity increased the cotton yield and therefore reduced the N_{2}O intensity (N_{2}O emission per lint yield) of this cropping system. Our data suggest that there is only limited scope to reduce absolute N_{2}O emissions by different irrigation intensities in irrigated cotton systems with summer dominated rainfall. However, the significant impact of the irrigation treatments on the N_{2}O intensity clearly shows that irrigation can easily be used to optimize the N_{2}O intensity of such a system.},
keywords = {Nutrient Cycling in Agroecosystems},
pubstate = {published},
tppubtype = {article}
}

@article{Huang2012,
title = {Nitrous oxide from sub-tropical horticultural soils: a time series analysis},
author = { X Huang and P. R. Grace and K Weier and K. Mengersen},
doi = {10.1071/SR11100},
year = {2012},
date = {2012-11-13},
journal = {Soil Research},
volume = {50},
number = {7},
pages = {596-606},
abstract = {Intensively managed pastures receive high inputs ofnitrogen (N) fertilizer, rendering them prone to high N losses via denitrification following intensive rainfall events. Intense rainfall events, which are predicted to increase in frequency with changes in global climate, increase the risk of denitrification losses from agro-ecosystems. Nitrification inhibitors (NI) have been promoted to mitigate N losses, however their effect on total denitrification (N_{2} and N_{2}O) and therefore their agronomic viability remains largely unknown. This study investigated the efficacy of the NI 3,4-dimethylpyrazole phosphate (DMPP) to reduce N_{2} and N_{2}O emissions after heavy rainfall from three pastures with different soil textures in subtropical Australia. Emissions of N_{2} and N_{2}O were measured over three weeks following the application of ^{15}N urea (36.8 kg N ha^{−1}) with and without DMPP. An intense rainfall event was simulated 10 days after fertilization to create saturated conditions in the topsoil. Emissions of N_{2}O decreased after day 1, reflecting a rapid shift towards complete denitrification. Unlike N_{2}O, N_{2} fluxes responded to the rainfall event with peak fluxes up to 3.8 kg N_{2}-N ha^{−1} day^{−1}. The main product of denitrification was N_{2}, which accounted for more than 95% of cumulative denitrification losses across sites. Cumulative N_{2} losses over 21 days remained below 4 kg N ha^{−1} for the well-drained sandy loam, while up to 28 kg N_{2}-N ha^{−1} were emitted from the clay and loam soils, demonstrating N_{2} emissions as a major pathway of N loss from intensively managed pastures. The magnitude of N_{2} losses across pasture sites reflects the combined effect of reduced soil gas diffusivity and microbial oxygen consumption on denitrification. DMPP reduced these N_{2} losses by more than 70%, but had no effect on N_{2}O emissions, providing the first field based evidence that DMPP can substantially reduce N_{2} emissions. The reduction of agronomically significant N_{2} losses highlights the potential of DMPP to mitigate the impact of increased rainfall intensity on denitrification losses thereby improving N use efficiency for intensively managed pastures.},
keywords = {Soil Research 50},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2012b,
title = {Nitrous oxide emissions from irrigated wheat in Australia: Impact of irrigation management},
author = { C Scheer and P. R. Grace and D.W Rowlings and J. Payero},
doi = {10.1007/s11104-012-1197-4},
year = {2012},
date = {2012-03-23},
journal = {Plant & Soil},
volume = {359},
number = {1},
pages = {351-362},
abstract = {"Background and aims
Irrigation management affects soil water dynamics as well as the soil microbial carbon and nitrogen turnover and potentially the biosphere-atmosphere exchange of greenhouse gasses (GHG). We present a study on the effect of three irrigation treatments on the emissions of nitrous oxide (N_{2}O) from irrigated wheat on black vertisols in South-Eastern Queensland, Australia.
Methods
Soil N_{2}O fluxes from wheat were monitored over one season with a fully automated system that measured emissions on a sub-daily basis. Measurements were taken from 3 subplots for each treatment within a randomized split-plot design.
Results Highest N_{2}O emissions occurred after rainfall or irrigation and the amount of irrigation water applied was found to influence the magnitude of these “emission pulses”. Daily N_{2}O emissions varied from −0.74 to 20.46 g N_{2}O-N ha^{−1} day^{−1} resulting in seasonal losses ranging from 0.43 to 0.75 kg N_{2}O-N ha^{−1} season^{ − 1} for the different irrigation treatments. Emission factors (EF = proportion of N fertilizer emitted as N_{2}O) over the wheat cropping season, uncorrected for background emissions, ranged from 0.2 to 0.4 % of total N applied for the different treatments. Highest seasonal N_{2}O emissions were observed in the treatment with the highest irrigation intensity; however, the N_{2}O intensity (N_{2}O emission per crop yield) was highest in the treatment with the lowest irrigation intensity.
Conclusions Our data suggest that timing and amount of irrigation can effectively be used to reduce N_{2}O losses from irrigated agricultural systems; however, in order to develop sustainable mitigation strategies the N_{2}O intensity of a cropping system is an important concept that needs to be taken into account."},
keywords = {Plant and Soil},
pubstate = {published},
tppubtype = {article}
}

@article{Rowlings2011,
title = {Environmental factors controlling temporal and spatial variability in the soil-atmosphere exchange of CO_{2}, CH_{4} and N_{2}O from an Australian subtropical rainforest.},
author = { D.W Rowlings and P. R. Grace and R Kiese and K.L. Weier},
doi = {10.1111/j.1365-2486.2011.02563.x},
year = {2011},
date = {2011-11-07},
journal = {Global Change Biology},
volume = {18},
pages = {726-738},
abstract = {The temporal variations in CO_{2}, CH_{4} and N_{2}O fluxes were measured over two consecutive years from February 2007 to March 2009 from a subtropical rainforest in south-eastern Queensland, Australia, using an automated sampling system. A concurrent study using an additional 30 manual chambers examined the spatial variability of emissions distributed across three nearby remnant rainforest sites with similar vegetation and climatic conditions. Interannual variation in fluxes of all gases over the 2 years was minimal, despite large discrepancies in rainfall, whereas a pronounced seasonal variation could only be observed for CO_{2} fluxes. High infiltration, drainage and subsequent high soil aeration under the rainforest limited N_{2}O loss while promoting substantial CH_{4} uptake. The average annual N_{2}O loss of 0.5 ± 0.1 kg N_{2}O-N ha^{−1} over the 2-year measurement period was at the lower end of reported fluxes from rainforest soils. The rainforest soil functioned as a sink for atmospheric CH_{4} throughout the entire 2-year period, despite periods of substantial rainfall. A clear linear correlation between soil moisture and CH_{4} uptake was found. Rates of uptake ranged from greater than 15 g CH_{4}-C ha^{−1} day^{−1} during extended dry periods to less than 2–5 g CH_{4}-C ha^{−1} day^{−1} when soil water content was high. The calculated annual CH_{4} uptake at the site was 3.65 kg CH_{4}-C ha^{−1} yr^{−1}. This is amongst the highest reported for rainforest systems, reiterating the ability of aerated subtropical rainforests to act as substantial sinks of CH_{4}. The spatial study showed N_{2}O fluxes almost eight times higher, and CH_{4} uptake reduced by over one-third, as clay content of the rainforest soil increased from 12% to more than 23%. This demonstrates that for some rainforest ecosystems, soil texture and related water infiltration and drainage capacity constraints may play a more important role in controlling fluxes than either vegetation or seasonal variability.},
keywords = {Global Change Biology},
pubstate = {published},
tppubtype = {article}
}

@article{Huang2011,
title = {Spatio-temporal variation in soil derived nitrous oxide emissions under sugarcane},
author = { X Huang and P. R. Grace and K. Mengersen},
doi = {10.1016/j.scitotenv.2011.07.044},
year = {2011},
date = {2011-10-01},
journal = {Science of the Total Environment},
volume = {21},
number = {21},
pages = {4572-4578},
abstract = {Nitrous oxide (N_{2}O) is a significant greenhouse gas with a global warming potential that is 300 times than that of carbon dioxide. Soil derived N_{2}O emissions usually display a high degree of spatial and temporal variability because of their dependence on soil chemical and physical properties, and climate dependent environmental factors. However, there is little research that incorporates spatial dependence in the estimation of N_{2}O emissions allowing for environmental factors in the same model. This study aims to examine the impact of two environmental factors (soil temperature and soil moisture) on N_{2}O emissions and explore the spatial structure of N_{2}O in the sub-tropical South East Queensland region of Australia. The replicated data on N_{2}O emissions and soil properties were collected at a typical sugarcane land site covering 25 uniform grid points across 3600 m^{2} between October 2007 and September 2008. A Bayesian conditional autoregressive (CAR) model was used to model spatial dependence. Results showed that soil moisture and soil temperature appeared to have substantially different effects on N_{2}O emissions after taking spatial dependence into account in the four seasons. There was a substantial variation in the spatial distribution of N_{2}O emission in the different seasons. The high N_{2}O emission regions were accompanied by high uncertainty and changed in varying seasons in this study site. Spatial CAR models might be more plausible to elucidate and account for the uncertainty arising from unclear variables and spatial variability in the assessment of N_{2}O emissions in soils, and more accurately identify relationships with key environmental factors and help to reduce the uncertainty of the soil parameters.},
keywords = {Science of the Total Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2011,
title = {Effect of biochar amendment on the soil-atmosphere exchange of greenhouse gases from an intensive subtropical pasture in Northern New South Wales, Australia.},
author = { C Scheer and P. R. Grace and D Rowlings and S. Kimber and L van Zwieten},
doi = {10.1007/s11104-011-0759-1},
year = {2011},
date = {2011-03-08},
journal = {Plant & Soil},
volume = {345},
number = {1},
pages = {47-58},
abstract = {We assessed the effect of biochar incorporation into the soil on the soil-atmosphere exchange of the greenhouse gases (GHG) from an intensive subtropical pasture. For this, we measured N_{2}O, CH_{4} and CO_{2} emissions with high temporal resolution from April to June 2009 in an existing factorial experiment where cattle feedlot biochar had been applied at 10 t ha^{−1} in November 2006. Over the whole measurement period, significant emissions of N_{2}O and CO_{2} were observed, whereas a net uptake of CH_{4} was measured. N_{2}O emissions were found to be highly episodic with one major emission pulse (up to 502 μg N_{2}O-N m^{−2} h^{−1}) following heavy rainfall. There was no significant difference in the net flux of GHGs from the biochar amended vs. the control plots. Our results demonstrate that intensively managed subtropical pastures on ferrosols in northern New South Wales of Australia can be a significant source of GHG. Our hypothesis that the application of biochar would lead to a reduction in emissions of GHG from soils was not supported in this field assessment. Additional studies with longer observation periods are needed to clarify the long term effect of biochar amendment on soil microbial processes and the emission of GHGs under field conditions.},
keywords = {Plant and Soil},
pubstate = {published},
tppubtype = {article}
}