@article{Friedl2015,
title = {Denitrification losses from an intensively managed sub-tropical pasture – Impact of soil moisture on the partitioning of N_{2} and N_{2}O emissions},
author = { J Friedl and C Scheer and D Rowlings and H McIntosh and A Strazzabosco and D Warner and P. Grace},
doi = {10.1016/j.soilbio.2015.09.016},
year = {2015},
date = {2015-09-25},
journal = {Soil Biology and Biochemistry},
volume = {92},
pages = {58-66},
abstract = {Intensively managed pastures in subtropical Australia under dairy production are nitrogen (N) loaded agro-ecosystems, with an increased pool of N available for denitrification. The magnitude of denitrification losses and N_{2}:N_{2}O partitioning in these agro-ecosystems is largely unknown, representing a major uncertainty when estimating total N loss and replacement. This study investigated the influence of different soil moisture contents on N_{2} and N_{2}O emissions from a subtropical dairy pasture in Queensland, Australia. Intact soil cores were incubated over 15 days at 80% and 100% water-filled pore space (WFPS), after the application of ^{15}N labelled nitrate, equivalent to 50 kg N ha^{−1}. This setup enabled the direct quantification of N_{2} and N_{2}O emissions following fertilisation using the ^{15}N gas flux method. The main product of denitrification in both treatments was N_{2}. N_{2} emissions exceeded N_{2}O emissions by a factor of 8 ± 1 at 80% WFPS and a factor of 17 ± 2 at 100% WFPS. The total amount of N-N_{2} lost over the incubation period was 21.27 kg ± 2.10 N_{2}-N ha^{−1} at 80% WFPS and 25.26 kg ± 2.79 kg ha^{−1} at 100% WFPS respectively. N_{2} emissions remained high at 100% WFPS, while related N_{2}O emissions decreased. At 80% WFPS, N_{2} emissions increased constantly over time while N_{2}O fluxes declined. Consequently, N_{2}/(N_{2} + N_{2}O) product ratios increased over the incubation period in both treatments. N_{2}/(N_{2} + N_{2}O) product ratios responded significantly to soil moisture, confirming WFPS as a key driver of denitrification. The substantial amount of fertiliser lost as N_{2} reveals the agronomic significance of denitrification as a major pathway of N loss for sub-tropical pastures at high WFPS and may explain the low fertiliser N use efficiency observed for these agro-ecosystems.},
keywords = {Soil Biology and Biochemistry},
pubstate = {published},
tppubtype = {article}
}

@article{Migliorati2015,
title = {Legumes or nitrification inhibitors to reduce N_{2}O emissions from subtropical cereal cropping systems in Oxisols?},
author = { M De Antoni Migliorati and W.J Parton and S.J Del Grosso and P.R Grace and M.J Bell and A Strazzabosco and D.W Rowlings and C Scheer and G. Harch},
doi = {10.1016/j.agee.2015.08.010},
year = {2015},
date = {2015-08-10},
journal = {Agriculture, Ecosystems and Environment},
volume = {213},
pages = {228-240},
abstract = {The DAYCENT biogeochemical model was used to investigate how the use of fertilizers coated with nitrification inhibitors and the introduction of legumes in the crop rotation can affect subtropical cereal production and N_{2}O emissions. The model was validated using comprehensive multi-seasonal, high-frequency dataset from two field investigations conducted on an Oxisol, which is the most common soil type in subtropical regions. Different N fertilizer rates were tested for each N management strategy and simulated under varying weather conditions. DAYCENT was able to reliably predict soil N dynamics, seasonal N_{2}O emissions and crop production, although some discrepancies were observed in the treatments with low or no added N inputs and in the simulation of daily N_{2}O fluxes. Simulations highlighted that the high clay content and the relatively low C levels of the Oxisol analyzed in this study limit the chances for significant amounts of N to be lost via deep leaching or denitrification. The application of urea coated with a nitrification inhibitor was the most effective strategy to minimize N_{2}O emissions. This strategy however did not increase yields since the nitrification inhibitor did not substantially decrease overall N losses compared to conventional urea. Simulations indicated that replacing part of crop N requirements with N mineralized by legume residues is the most effective strategy to reduce N_{2}O emissions and support cereal productivity. The results of this study show that legumes have significant potential to enhance the sustainable and profitable intensification of subtropical cereal cropping systems in Oxisols.},
keywords = {Agriculture, Ecosystems and Environment},
pubstate = {published},
tppubtype = {article}
}

@article{DeAntoniMigliorati2015,
title = {Legume pastures can reduce N_{2}O emissions intensity in subtropical cereal cropping systems},
author = { M De Antoni Migliorati and Grace P.R Bell and D Rowlings and C. Scheer},
doi = {10.1016/j.agee.2015.02.007},
year = {2015},
date = {2015-06-01},
journal = {Agriculture Ecosystems and Environment},
volume = {204},
pages = {27-39},
abstract = {Alternative sources of N are required to bolster subtropical cereal production without increasing N_{2}O emissions from these agro-ecosystems. The reintroduction of legumes in cereal cropping systems is a possible strategy to reduce synthetic N inputs but elevated N_{2}O losses have sometimes been observed after the incorporation of legume residues. However, the magnitude of these losses is highly dependent on local conditions and very little data are available for subtropical regions. The aim of this study was to assess whether, under subtropical conditions, the N mineralised from legume residues can substantially decrease the synthetic N input required by the subsequent cereal crop and reduce overall N_{2}O emissions during the cereal cropping phase. Using a fully automated measuring system, N_{2}O emissions were monitored in a cereal crop (sorghum) following a legume pasture and compared to the same crop in rotation with a grass pasture. Each crop rotation included a nil and a fertilised treatment to assess the N availability of the residues. The incorporation of legumes provided enough readily available N to effectively support crop development but the low labile C left by these residues is likely to have limited denitrification and therefore N_{2}O emissions. As a result, N_{2}O emissions intensities (kg N_{2}O-N yield^{−1} ha^{−1}) were considerably lower in the legume histories than in the grass. Overall, these findings indicate that the C supplied by the crop residue can be more important than the soil NO_{3}^{−} content in stimulating denitrification and that introducing a legume pasture in a subtropical cereal cropping system is a sustainable practice from both environmental and agronomic perspectives.},
keywords = {Agriculture Ecosystems and Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Lam2015,
title = {Measurement and mitigation of nitrous oxide emissions from a high nitrogen input vegetable system},
author = {Shu Kee Lam and Helen Suter and Rohan Davies and Mei Bai and Jianlei Sun and Deli Chen},
doi = {10.1038/srep08208},
year = {2015},
date = {2015-05-06},
journal = {Scientific Reports},
volume = {5},
number = {8208},
abstract = {The emission and mitigation of nitrous oxide (N_{2}O) from high nitrogen (N) vegetable systems is not well understood. Nitrification inhibitors are widely used to decrease N_{2}O emissions in many cropping systems. However, most N_{2}O flux measurements and inhibitor impacts have been made with small chambers and have not been investigated at a paddock-scale using micrometeorological techniques. We quantified N_{2}O fluxes over a four ha celery paddock using open-path Fourier Transform Infrared spectroscopy in conjunction with a backward Lagrangian stochastic model, in addition to using a closed chamber technique. The celery crop was grown on a sandy soil in southern Victoria, Australia. The emission of N_{2}O was measured following the application of chicken manure and N fertilizer with and without the application of a nitrification inhibitor 3, 4-dimethyl pyrazole phosphate (DMPP). The two techniques consistently demonstrated that DMPP application reduced N_{2}O emission by 37–44%, even though the N_{2}O fluxes measured by a micrometeorological technique were more than 10 times higher than the small chamber measurements. The results suggest that nitrification inhibitors have the potential to mitigate N_{2}O emission from intensive vegetable production systems, and that the national soil N_{2}O emission inventory assessments and modelling predictions may vary with gas measurement techniques.},
keywords = {Inhibitors for reducing emissions},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2015,
title = {Nitrogen management is the key for low-emission wheat production in Australia: A life cycle perspective},
author = {Weijin Wang and Ram C.Dalal},
doi = {10.1016/j.eja.2015.02.007},
year = {2015},
date = {2015-05-01},
journal = {European Journal of Agronomy},
volume = {66},
pages = {74–82},
abstract = {Farm management affects the global greenhouse gas (GHG) budget by changing not only soil organic
carbon (SOC) stocks and nitrous oxide (N2 O) emissions but also other pre-farm, on-farm and
off-site emissions. The life cycle assessment (LCA) approach has been widely adopted to assess the
“carbon footprint” of agricultural products, but rarely used as a tool to identify effective
mitigation strategies. In this study, the global warming impacts of no-till (NT) vs. conventional
till (CT), stubble retention (SR) vs stubble burning (SB), and N fertilization (NF) vs. no N
fertilization (N0) in an Australian wheat cropping system were assessed using in situ measurements
of N2 O fluxes over three years, SOC changes over forty years and including other supply chain GHG
sources and sinks. The results demonstrated the importance of full GHG accounting compared to
considering SOC changes or N2 O emissions alone for assessing the global warming impacts of
different management practices, and highlighted the significance of accurately accounting for SOC
changes and N2 O emissions in LCAs. The GHG footprints of wheat production were on averaged 475 kg
carbon dioxide equivalent (CO2 -e) ha−1 (or 186 kg CO2 -e t−1 grain) higher under NF than N0. Where
fertilizer N was applied (70 kg N ha−1 ), the life cycle emissions were 200 kg CO2 -e ha−1 (or 87
t−1 grain) lower under NT than CT and 364 kg CO2 -e ha−1 (or 155 t−1 grain) lower under SR than SB.
Classification of the emission sources/sinks and re-calculation of published data indicated that
under the common practices of SR combined with NT, N-related GHG emissions contributed 60–95% of
the life cycle emissions in the predominantly rain-fed wheat production systems in Australia.
Therefore, future mitigation efforts should aim to improve N use efficiency, explore non-synthetic N
sources, and most importantly avoid excessive N fertilizer use whilst practising NT and SR.},
keywords = {Reducing emissions through improved nitrogen use efficiency},
pubstate = {published},
tppubtype = {article}
}

@article{Rowlings2015,
title = {Rainfall variability drives interannual variation in N_{2}O emissions from a humid, subtropical pasture},
author = { D.W Rowlings and P.R Grace and C Scheer and S. Liu},
doi = {10.1016/j.scitotenv.2015.01.011},
year = {2015},
date = {2015-01-06},
journal = {Science of the Total Environment},
volume = {512–513},
pages = {8-18},
abstract = {"Variations in interannual rainfall totals can lead to large uncertainties in annual N_{2}O emission budget estimates from short term field studies. The interannual variation in nitrous oxide (N_{2}O) emissions from a subtropical pasture in Queensland, Australia, was examined using continuous measurements of automated chambers over 2 consecutive years. Nitrous oxide emissions were highest during the summer months and were highly episodic, related more to the size and distribution of rain events than soil water content. Over 48% of the total N_{2}O emitted was lost in just 16% of measurement days.
Interannual variation in annual N_{2}O estimates was high, with cumulative emissions increasing with decreasing rainfall. Cumulative emissions averaged 1826.7 ± 199.9 g N_{2}O-N ha^{− 1} yr^{− 1} over the two year period, though emissions from 2008 (2148 ± 273 g N_{2}O-N ha^{− 1} yr^{− 1}) were 42% higher than 2007 (1504 ± 126 g N_{2}O-N ha^{− 1} yr^{− 1}). This increase in annual emissions coincided with almost half of the summer precipitation from 2007 to 2008. Emissions dynamics were chiefly driven by the distribution and size of rain events which varied on a seasonal and annual basis. Sampling frequency effects on cumulative N_{2}O flux estimation were assessed using a jackknife technique to inform future manual sampling campaigns. Test subsets of the daily measured data were generated for the pasture and two adjacent land-uses (rainforest and lychee orchard) by selecting measured flux values at regular time intervals ranging from 1 to 30 days. Errors associated with weekly sampling were up to 34% of the sub-daily mean and were highly biased towards overestimation if strategically sampled following rain events. Sampling time of day also played a critical role. Morning sampling best represented the 24 hour mean in the pasture, whereas sampling at noon proved the most accurate in the shaded rainforest and lychee orchard."},
keywords = {Science of the Total Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Migliorati2014,
title = {Assessing agronomic and environmental implications of different N fertilisation strategies in grain cropping systems in Oxisols.},
author = { M De Antoni Migliorati and M Bell and P. R. Grace and D. W. Rowlings and C Scheer and A. Strazzabosco},
doi = {10.1007/s10705-014-9655-4},
year = {2014},
date = {2014-11-14},
journal = {Nutrient Cycling in Agroecosystems},
volume = {100},
number = {3},
pages = {369-382},
abstract = {A multi-season ^{15}N tracer recovery experiment was conducted on an Oxisol cropped with wheat, maize and sorghum to compare crop N recoveries of different fertilisation strategies and determine the main pathways of N losses that limit N recovery in these agroecosystems. In the wheat and maize seasons, ^{15}N-labelled fertiliser was applied as conventional urea (CONV) and urea coated with a nitrification inhibitor (DMPP). In sorghum, the fate of ^{15}N-labelled urea was monitored in this crop following a legume ley pasture (L70) or a grass ley pasture (G100). The fertiliser N applied to sorghum in the legume-cereal rotation was reduced (70 kg N ha^{−1}) compared to the grass-cereal (100 kg N ha^{−1}) to assess the availability of the N residual from the legume ley pasture. Average crop N recoveries were 73 % (CONV) and 77 % (DMPP) in wheat and 50 % (CONV) and 51 % (DMPP) in maize, while in sorghum were 71 % (L70) and 53 % (G100). Data gathered in this study indicate that the intrinsic physical and chemical conditions of Oxisols can be extremely effective in limiting N losses via deep leaching or denitrification. Elevated crop ^{15}N recoveries can be therefore obtained in subtropical Oxisols using conventional urea while in these agroecosystems DMPP urea has no significant scope to increase fertiliser N recovery in the crop. Overall, introducing a legume phase to limit the fertiliser N requirements of the following cereal crop proved to be the most effective strategy to reduce N losses and increase fertiliser N recovery.},
keywords = {Nutrient Cycling in Agroecosystems},
pubstate = {published},
tppubtype = {article}
}

@article{Bai2014,
title = {Use of open-path FTIR and inverse dispersion technique to quantify gaseous nitrogen loss from an intensive vegetable production site.},
author = {Mei Bai and Helen Suter and Shu Kee Lam and Jianlei Sun and Deli Chen },
doi = {10.1016/j.atmosenv.2014.06.013},
year = {2014},
date = {2014-09-01},
journal = {Atmospheric Environment},
volume = {94},
pages = {687–691},
abstract = {An open-path Fourier transform infrared (OP-FTIR) spectroscopic technique in combination with a backward Lagrangian stochastic (bLS) dispersion model (WindTrax) can be used to simultaneously measure gaseous emissions of N2O, NH3, CH4 and CO2. We assessed the capability of this technique for measuring NH3 and N2O emissions following the application of calcium nitrate (Ca(NO3)2), Nitrophoska (NPK) and chicken manure on a celery farm at Boneo, Victoria, during April and May 2013. We found that the OP-FTIR/WindTrax method was able to measure the diurnal variation in NH3 flux from the field site following application of chicken manure with measured emissions ranging from approximately 0.1–9.8 kg NH3–N ha−1 day−1. The OP-FTIR/WindTrax method also detected a diurnal variation in N2O flux of 1.5–6.2 kg N2O–N ha−1 day−1 and N2O flux increased in response to application of the Ca(NO3)2. We concluded that the OP-FTIR/WindTrax technique can quantify gaseous N loss from vegetable production systems.},
keywords = {Inhibitors for reducing emissions},
pubstate = {published},
tppubtype = {article}
}

@article{Nguyen2014,
title = {Greenhouse gas emissions from sub-tropical agricultural soils after addition of organic by-products.},
author = { H. Dai Nguyen and J. Biala and P. R. Grace and C Scheer and D. W. Rowlings },
doi = {10.1186/2193-1801-3-491},
year = {2014},
date = {2014-08-30},
journal = {SpringerPlus},
volume = {3},
pages = {491},
abstract = {As the cost of mineral fertilisers increases globally, organic soil amendments (OAs) from agricultural sources are increasingly being used as substitutes for nitrogen. However, the impact of OAs on the production of greenhouse gases (CO_{2} and N_{2}O) is not well understood. A 60-day laboratory incubation experiment was conducted to investigate the impacts of applying OAs (equivalent to 296 kg N ha^{-1} on average) on N_{2}O and CO_{2} emissions and soil properties of clay and sandy loam soils from sugar cane production. The experiment included 6 treatments, one being an un-amended (UN) control with addition of five OAs being raw mill mud (MM), composted mill mud (CM), high N compost (HC), rice husk biochar (RB), and raw mill mud plus rice husk biochar (MB). These OAs were incubated at 60, 75 and 90% water-filled pore space (WFPS) at 25°C with urea (equivalent to 200 kg N ha^{-1}) added to the soils thirty days after the incubation commenced. Results showed WFPS did not influence CO_{2} emissions over the 60 days but the magnitude of emissions as a proportion of C applied was RB < CM < MB < HC < MM. Nitrous oxide emissions were significantly less in the clay soil compared to the sandy loam at all WFPS, and could be ranked RB < MB < MM < CM < UN < HC. These results led to linear models being developed to predict CO_{2} and N_{2}O emissions as a function of the dry matter and C/N ratio of the OAs, WFPS, and the soil CEC. Application of RB reduced N_{2}O emissions by as much as 42-64% depending on WFPS. The reductions in both CO_{2} and N_{2}O emissions after application of RB were due to a reduced bioavailability of C and not immobilisation of N. These findings show that the effect of OAs on soil GHG emissions can vary substantially depending on their chemical properties. OAs with a high availability of labile C and N can lead to elevated emissions of CO_{2} and N_{2}O, while rice husk biochar showed potential in reducing overall soil GHG emissions.},
keywords = {SpringerPlus},
pubstate = {published},
tppubtype = {article}
}

@article{Moore2014,
title = {Mathematical modelling for improved greenhouse gas balances, agro-ecosystems and policy development: lessons from the Australian experience},
author = { A Moore and P Thorburn and R Eckard and P. R. Grace and E Wang and D. Chen},
doi = {10.1002/wcc.304},
year = {2014},
date = {2014-08-28},
journal = {WIREs Climate Change},
volume = {5},
number = {6},
pages = {735-752},
abstract = {If the land sector is to make significant contributions to mitigating anthropogenic greenhouse gas (GHG) emissions in coming decades, it must do so while concurrently expanding production of food and fiber. In our view, mathematical modeling will be required to provide scientific guidance to meet this challenge. In order to be useful in GHG mitigation policy measures, models must simultaneously meet scientific, software engineering, and human capacity requirements. They can be used to understand GHG fluxes, to evaluate proposed GHG mitigation actions, and to predict and monitor the effects of specific actions; the latter applications require a change in mindset that has parallels with the shift from research modeling to decision support. We compare and contrast 6 agro-ecosystem models (FullCAM, DayCent, DNDC, APSIM, WNMM, and AgMod), chosen because they are used in Australian agriculture and forestry. Underlying structural similarities in the representations of carbon flows though plants and soils in these models are complemented by a diverse range of emphases and approaches to the subprocesses within the agro-ecosystem. None of these agro-ecosystem models handles all land sector GHG fluxes, and considerable model-based uncertainty exists for soil C fluxes and enteric methane emissions. The models also show diverse approaches to the initialisation of model simulations, software implementation, distribution, licensing, and software quality assurance; each of these will differentially affect their usefulness for policy-driven GHG mitigation prediction and monitoring. Specific requirements imposed on the use of models by Australian mitigation policy settings are discussed, and areas for further scientific development of agro-ecosystem models for use in GHG mitigation policy are proposed.},
keywords = {WIREs Climate Change},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2014,
title = {Impact of nitrification inhibitor (DMPP) on soil nitrous oxide emissions from an intensive broccoli production system in sub-tropical Australia},
author = { C Scheer and D. W. Rowlings and M Firrel and P Deuter and S Morris and P. R. Grace },
doi = {10.1016/j.soilbio.2014.07.006},
year = {2014},
date = {2014-07-06},
journal = {Soil Biology and Biochemistry},
volume = {77},
pages = {243-251},
abstract = {Vegetable cropping systems are often characterised by high inputs of nitrogen fertiliser. Elevated emissions of nitrous oxide (N_{2}O) can be expected as a consequence. In order to mitigate N_{2}O emissions from fertilised agricultural fields, the use of nitrification inhibitors, in combination with ammonium based fertilisers, has been promoted. However, no data is currently available on the use of nitrification inhibitors in sub-tropical vegetable systems. A field experiment was conducted to investigate the effect of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on N_{2}O emissions and yield from broccoli production in sub-tropical Australia. Soil N_{2}O fluxes were monitored continuously (3 h sampling frequency) with fully automated, pneumatically operated measuring chambers linked to a sampling control system and a gas chromatograph. Cumulative N_{2}O emissions over the 5 month observation period amounted to 298 g-N/ha, 324 g-N/ha, 411 g-N/ha and 463 g-N/ha in the conventional fertiliser (CONV), the DMPP treatment (DMPP), the DMMP treatment with a 10% reduced fertiliser rate (DMPP-red) and the zero fertiliser (0N), respectively. The temporal variation of N_{2}O fluxes showed only low emissions over the broccoli cropping phase, but significantly elevated emissions were observed in all treatments following broccoli residues being incorporated into the soil. Overall 70–90% of the total emissions occurred in this 5 weeks fallow phase. There was a significant inhibition effect of DMPP on N_{2}O emissions and soil mineral N content over the broccoli cropping phase where the application of DMPP reduced N_{2}O emissions by 75% compared to the standard practice. However, there was no statistical difference between the treatments during the fallow phase or when the whole season was considered. This study shows that DMPP has the potential to reduce N_{2}O emissions from intensive vegetable systems, but also highlights the importance of post-harvest emissions from incorporated vegetable residues. N_{2}O mitigation strategies in vegetable systems need to target these post-harvest emissions and a better evaluation of the effect of nitrification inhibitors over the fallow phase is needed.},
keywords = {Soil Biology and Biochemistry},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2014,
title = {Modeling nitrous oxide emissions from irrigated agriculture: Testing DAYCENT with high frequency measurements},
author = { C Scheer and S Del Grosso and W Parton and D. W. Rowlings and P. R. Grace},
doi = {10.1890/13-0570.1},
year = {2014},
date = {2014-04-01},
journal = {Ecological Applications},
volume = {24},
number = {3},
pages = {528-538},
abstract = {A unique high temporal frequency data set from an irrigated cotton–wheat rotation was used to test the agroecosystem model DayCent to simulate daily N_{2}O emissions from subtropical vertisols under different irrigation intensities. DayCent was able to simulate the effect of different irrigation intensities on N_{2}O fluxes and yield, although it tended to overestimate seasonal fluxes during the cotton season. DayCent accurately predicted soil moisture dynamics and the timing and magnitude of high fluxes associated with fertilizer additions and irrigation events. At the daily scale we found a good correlation of predicted vs. measured N_{2}O fluxes (\emph{r}^{2} = 0.52), confirming that DayCent can be used to test agricultural practices for mitigating N_{2}O emission from irrigated cropping systems. A 25-year scenario analysis indicated that N_{2}O losses from irrigated cotton–wheat rotations on black vertisols in Australia can be substantially reduced by an optimized fertilizer and irrigation management system (i.e., frequent irrigation, avoidance of excessive fertilizer application), while sustaining maximum yield potentials.},
keywords = {Ecological Applications},
pubstate = {published},
tppubtype = {article}
}

@article{Migliorati2014,
title = {Influence of different nitrogen rates and DMPP nitrification inhibitor on annual N_{2}O emissions from a subtropical wheat–maize cropping system},
author = { M De Antoni Migliorati and C Scheer and P. R. Grace and D. W. Rowlings and M Bell and J. McGree},
doi = {10.1016/j.agee.2014.01.016},
year = {2014},
date = {2014-03-15},
journal = {Agriculture, Ecosystems and Environment},
volume = {186},
number = {15},
pages = {33-43},
abstract = {Global cereal production will need to increase by 50% to 70% to feed a world population of about 9 billion by 2050. This intensification is forecast to occur mostly in subtropical regions, where warm and humid conditions can promote high N_{2}O losses from cropped soils. To secure high crop production without exacerbating N_{2}O emissions, new nitrogen (N) fertiliser management strategies are necessary. This one-year study evaluated the efficacy of a nitrification inhibitor (3,4-dimethylpyrazole phosphate—DMPP) and different N fertiliser rates to reduce N_{2}O emissions in a wheat–maize rotation in subtropical Australia. Annual N_{2}O emissions were monitored using a fully automated greenhouse gas measuring system. Four treatments were fertilized with different rates of urea, including a control (40 kg-N ha^{−1} year^{−1}), a conventional N fertiliser rate adjusted on estimated residual soil N (120 kg-N ha^{−1} year^{−1}), a conventional N fertiliser rate (240 kg-N ha^{−1} year^{−1}) and a conventional N fertiliser rate (240 kg-N ha^{−1} year^{−1}) with nitrification inhibitor (DMPP) applied at top dressing. The maize season was by far the main contributor to annual N_{2}O emissions due to the high soil moisture and temperature conditions, as well as the elevated N rates applied. Annual N_{2}O emissions in the four treatments amounted to 0.49, 0.84, 2.02 and 0.74 kg N_{2}O–N ha^{−1} year^{−1}, respectively, and corresponded to emission factors of 0.29%, 0.39%, 0.69% and 0.16% of total N applied. Halving the annual conventional N fertiliser rate in the adjusted N treatment led to N_{2}O emissions comparable to the DMPP treatment but extensively penalised maize yield. The application of DMPP produced a significant reduction in N_{2}O emissions only in the maize season. The use of DMPP with urea at the conventional N rate reduced annual N_{2}O emissions by more than 60% but did not affect crop yields. The results of this study indicate that: (i) future strategies aimed at securing subtropical cereal production without increasing N_{2}O emissions should focus on the fertilisation of the summer crop; (ii) adjusting conventional N fertiliser rates on estimated residual soil N is an effective practice to reduce N_{2}O emissions but can lead to substantial yield losses if the residual soil N is not assessed correctly; (iii) the application of DMPP is a feasible strategy to reduce annual N_{2}O emissions from sub-tropical wheat–maize rotations. However, at the N rates tested in this study DMPP urea did not increase crop yields, making it impossible to recoup extra costs associated with this fertiliser. The findings of this study will support farmers and policy makers to define effective fertilisation strategies to reduce N_{2}O emissions from subtropical cereal cropping systems while maintaining high crop productivity. More research is needed to assess the use of DMPP urea in terms of reducing conventional N fertiliser rates and subsequently enable a decrease of fertilisation costs and a further abatement of fertiliser-induced N_{2}O emissions.},
keywords = {Agriculture, Ecosystems and Environment},
pubstate = {published},
tppubtype = {article}
}

@article{Nguyen2014,
title = {Determining gas sampling timelines for estimating emissions in small chamber incubation experiments},
author = { D. H. Nguyen and P. R. Grace and C Scheer and D. W. Rowlings},
doi = {10.9790/3021-04241416},
year = {2014},
date = {2014-02-01},
journal = {IOSR Journal of Engineering},
volume = {4},
number = {2},
pages = {14-16},
abstract = {A laboratory experiment was set up in small chambers for monitoring greenhouse gas emissions and determining the most suitable time for sampling. A six-treatment experiment was conducted, including a one week pre-incubation and a week for incubation. Timelines for sampling were 1, 2, 3, 6 and 24 hours after closing the lid of the incubation chambers. Variation in greenhouse gas fluxes was high due to the time of sampling. The rates of gas emissions increased in first three hours and decreased afterward. The rates of greenhouse gas emissions at 3 hours after closing lids was close to the mean for the 24-h period.},
keywords = {IOSR Journal of Engineering},
pubstate = {published},
tppubtype = {article}
}

@article{Morris2013,
title = {Improving the statistical preparation for measuring soil N_{2}O flux by closed chamber},
author = { S. G Morris and S. W Kimber and L van Zwieten and P. R. Grace},
doi = {10.1016/j.scitotenv.2013.02.032},
year = {2013},
date = {2013-11-01},
journal = {Science of the Total Environment},
volume = {465},
pages = {166-172},
abstract = {Nitrous oxide emissions from soil are known to be spatially and temporally volatile. Reliable estimation of emissions over a given time and space depends on measuring with sufficient intensity but deciding on the number of measuring stations and the frequency of observation can be vexing. The question of low frequency manual observations providing comparable results to high frequency automated sampling also arises. Data collected from a replicated field experiment was intensively studied with the intention to give some statistically robust guidance on these issues. The experiment had nitrous oxide soil to air flux monitored within 10 m by 2.5 m plots by automated closed chambers under a 3 h average sampling interval and by manual static chambers under a three day average sampling interval over sixty days. Observed trends in flux over time by the static chambers were mostly within the auto chamber bounds of experimental error. Cumulated nitrous oxide emissions as measured by each system were also within error bounds. Under the temporal response pattern in this experiment, no significant loss of information was observed after culling the data to simulate results under various low frequency scenarios. Within the confines of this experiment observations from the manual chambers were not spatially correlated above distances of 1 m. Statistical power was therefore found to improve due to increased replicates per treatment or chambers per replicate. Careful after action review of experimental data can deliver savings for future work.},
keywords = {Science of the Total Environment},
pubstate = {published},
tppubtype = {article}
}