@article{Delden2016,
title = {Urbanisation-related land use change from forest and pasture into turf grass modifies soil nitrogen cycling and increases N_{2}O emissions},
author = {L. Van Delden and D. W. Rowlings and C. Scheer and P.R. Grace},
doi = {10.5194/bg-13-6095-2016},
year = {2016},
date = {2016-11-07},
journal = {Biogeosciences},
volume = {13},
pages = {6095-6106},
abstract = {Urbanisation is becoming increasingly important in terms of climate change and ecosystem functionality worldwide. We are only beginning to understand how the processes of urbanisation influence ecosystem dynamics, making peri-urban environments more vulnerable to nutrient losses. Brisbane in South East Queensland has the most extensive urban sprawl of all Australian cities. This research estimated the environmental impact of land use change associated with urbanisation by examining soil nitrogen (N) turnover and subsequent nitrous oxide (N_{2}O) emissions using a fully automated system that measured emissions on a sub-daily basis. There was no significant difference in soil N_{2}O emissions between the native dry sclerophyll eucalypt forest and an extensively grazed pasture, wherefrom only low annual emissions were observed amounting to 0.1 and 0.2 kg N_{2}O ha^{−1} yr^{−1}, respectively. The establishment of a fertilised turf grass lawn increased soil N_{2}O emissions 18-fold (1.8 kg N_{2}O ha^{−1} yr^{−1}), with highest emissions occurring in the first 2 months after establishment. Once established, the turf grass lawn presented relatively low N_{2}O emissions for the rest of the year, even after fertilisation and rain events. Soil moisture was significantly higher, and mineralised N accumulated in the fallow plots, resulting in the highest N_{2}O emissions (2.8 kg N_{2}O ha^{−1} yr^{−1}) and significant nitrate (NO_{3}^{−}) losses, with up to 63 kg N ha^{−1} lost from a single rain event due to reduced plant cover removal. The study concludes that urbanisation processes creating peri-urban ecosystems can greatly modify N cycling and increase the potential for losses in the form of N_{2}O and NO_{3}^{−}.},
keywords = {Biogeosciences},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2016,
title = {An improved ^{15}N tracer approach to study denitrification and nitrogen turnover in soil incubations},
author = {C. Scheer and R. Meier and N. Bruggemann and P. R. Grace and M.Dannenmann},
doi = {10.1002/rcm.7689},
year = {2016},
date = {2016-08-12},
journal = {Rapid Communications in Mass Spectrometry},
volume = {30},
number = {18},
abstract = {"Rationale
Denitrification (the reduction of oxidized forms of inorganic nitrogen (N) to N_{2}O and N_{2}) from upland soils is considered to be the least well-understood process in the global N cycle. The main reason for this lack of understanding is that the terminal product (N_{2}) of denitrification is extremely difficult to measure against the large atmospheric background.
Methods
We describe a system that combines the ^{15}N-tracer technique with a 40-fold reduced N_{2} (2% v/v) atmosphere in a fully automated incubation setup for direct quantification of N_{2} and N_{2}O emissions. The \emph{δ}^{15}N values of the emitted N_{2} and N_{2}O were determined using a custom-built gas preparation unit that was connected to a DELTA V Plus isotope ratio mass spectrometer. The system was tested on a pasture soil from sub-tropical Australia under different soil moisture conditions and combined with ^{15}N tracing in extractable soil N pools to establish a full N balance.
Results
The method proved to be highly sensitive for detecting N_{2} (1.12 μg N h^{−1} kg^{−1} dry soil (ds)) and N_{2}O (0.36 μg N h^{−1} kg^{−1} ds) emissions. The main end product of denitrification in the investigated soil was N_{2}O for both water contents, with N_{2} accounting for only 3% to 13% of the total denitrification losses. Between 90 and 95% of the added ^{15}N fertiliser could be recovered in N gases and extractable soil N pools.
Conclusions The high and N_{2}O-dominated denitrification rates found in this study are pointing at both the high ecological and the agronomic importance of denitrification in subtropical pasture soils. The new system allows for a direct and highly sensitive detection of N_{2} and N_{2}O fluxes from soils and may help to significantly improve our mechanistic understanding of N cycling and denitrification in terrestrial agro-ecosystems. Copyright © 2016 John Wiley & Sons, Ltd."},
keywords = {Rapid Communications in Mass Spectrometry},
pubstate = {published},
tppubtype = {article}
}

@article{Lester2016,
title = {Agronomic responses of grain sorghum to DMPP-treated urea on contrasting soil types in north-eastern Australia},
author = {David W. Lester and Michael J. Bell and Kerry L. Bell and M De Antoni Migliorati and Clemens Scheer and David Rowlings and Peter R. Grace},
doi = {10.1071/SR15337},
year = {2016},
date = {2016-07-27},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {565-571},
abstract = {Grain sorghum grown in north-eastern Australia’s cropping region increasingly requires nitrogen (N) fertiliser to supplement the soil available N supply. The rates of N required can be high when fallows between crop seasons are short (higher cropping intensities) and when yield potentials are high.

Fertiliser N is typically applied before or at crop sowing and is vulnerable to environmental loss in the period between application and significant crop N demand due to potentially intense rainfall events in the summer-dominant rainfall environment.

Nitrification inhibitors added to urea can reduce certain gaseous loss pathways but the agronomic efficacy of these products has not been explored. Urea and urea coated with the nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) were compared in sorghum crops grown at five research sites over consecutive summer sorghum growing seasons in south-east Queensland. Products were compared in terms of crop responses in dry matter, N uptake and grain yield, with DMPP found to produce only subtle increases on grain yield. There was no effect on dry matter or N uptake. Outcomes suggest any advantages from use of DMPP in this region are most significant in situations where higher fertiliser application rates (>80 kg N/ha) are required.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Grace2016,
title = {Emission factors for estimating fertiliser-induced nitrous oxide emissions from clay soils in Australia’s irrigated cotton industry},
author = {Peter R. Grace and Iurii Shcherbak and Ben Macdonald and Clemens Scheer and David Rowlings},
doi = {10.1071/SR16091},
year = {2016},
date = {2016-07-25},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {598-603},
abstract = {As a significant user of nitrogen (N) fertilisers, the Australian cotton industry is a major source of soil-derived nitrous oxide (N_{2}O) emissions. A country-specific (Tier 2) fertiliser-induced emission factor (EF) can be used in national greenhouse gas inventories or in the development of N_{2}O emissions offset methodologies provided the EFs are evidence based. A meta-analysis was performed using eight individual N_{2}O emission studies from Australian cotton studies to estimate EFs. Annual N_{2}O emissions from cotton grown on Vertosols ranged from 0.59 kg N ha^{–1} in a 0N control to 1.94 kg N ha^{–1} in a treatment receiving 270 kg N ha^{–1}. Seasonal N_{2}O estimates ranged from 0.51 kg N ha^{–1} in a 0N control to 10.64 kg N ha^{–1} in response to the addition of 320 kg N ha^{–1}. A two-component (linear + exponential) statistical model, namely EF (%) = 0.29 + 0.007(e^{0.037}\textit{^{N}} – 1)/\textit{N}, capped at 300 kg N ha^{–1} describes the N_{2}O emissions from lower N rates better than an exponential model and aligns with an EF of 0.55% using a traditional linear regression model.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Dougherty2016,
title = {Nitrification (DMPP) and urease (NBPT) inhibitors had no effect on pasture yield, nitrous oxide emissions, or nitrate leaching under irrigation in a hot-dry climate},
author = {Warwick J. Dougherty and Damian Collins and Lukas Van Zwieten and David W. Rowlings},
doi = {10.1071/SR15330},
year = {2016},
date = {2016-07-25},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {675-683},
abstract = {Modern dairy farming in Australia relies on substantial inputs of fertiliser nitrogen (N) to underpin economic production. However, N lost from dairy systems represents an opportunity cost and can pose several environmental risks. N-cycle inhibitors can be co-applied with N fertilisers to slow the conversion of urea to ammonium to reduce losses via volatilisation, and slow the conversion of ammonium to nitrate to minimise leaching of nitrate and gaseous losses via nitrification and denitrification. In a field campaign in a high input ryegrass–kikuyu pasture system we compared the soil N pools, losses and pasture production between (a) urea coated with the nitrification inhibitor 3,4-dimethyl pyrazole phosphate (b) urea coated with the urease inhibitor N-(\textit{n}-butyl) thiophosphoric triamide and (c) standard urea. There was no treatment effect (\textit{P} > 0.05) on soil mineral N, pasture yield, nitrous oxide flux or leaching of nitrate compared to standard urea. We hypothesise that at our site, because gaseous losses were highly episodic (rainfall was erratic and displayed no seasonal rainfall nor soil wetting pattern) that there was a lack of coincidence of N application and conditions conducive to gaseous losses, thus the effectiveness of the inhibitor products was minimal and did not result in an increase in pasture yield. There remains a paucity of knowledge on N-cycle inhibitors in relation to their effective use in field system to increase N use efficiency. Further research is required to define under what field conditions inhibitor products are effective in order to be able to provide accurate advice to managers of N in production systems.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Macdonald2016,
title = {Contribution of the cotton irrigation network to farm nitrous oxide emissions},
author = {B. C. T. Macdonald and A. Nadelko and Y. Chang and M. Glover and S. Warneke},
doi = {10.1071/SR15273},
year = {2016},
date = {2016-07-25},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {651-658},
abstract = {Nitrous oxide (N_{2}O) is a potent greenhouse gas, and agriculture is the dominant source of N_{2}O-N emissions. The Australian cotton industry requires high inputs of N to maintain high lint quality and yields; however, over-fertilisation with N is symptomatic of the industry. Up to 3.5% of N fertiliser applied is lost directly from cotton fields as N_{2}O gas. Excess N may also be lost via erosion, deep-drainage, leaching and runoff, and may subsequently form indirect N_{2}O emissions. The estimate by the Intergovernmental Panel on Climate Change (IPCC) suggests that 0.0025 kg N_{2}O-N is produced indirectly from groundwater and surface drainage for each kg N lost via runoff and leaching, although this estimate carries a large degree of uncertainty. This study is the first to address the lack of indirect N_{2}O emission data from irrigated cotton-farming systems. Indirect emissions were determined from total N concentrations in irrigation runoff by using the IPCC emission factor and from measurements of dissolved N_{2}O during the first four irrigations (October–December 2013). Total indirect N_{2}O emissions from the surface of the irrigation network over 3 months when estimated by the dissolved-N_{2}O method were 0.503 ± 0.339 kg ha^{–1}. By contrast, N_{2}O emissions estimated by the IPCC methodology were 0.843 ± 0.022 kg ha^{–1} irrigation surface area. Over the same period of measurement, direct land-surface emissions were 1.44 kg N_{2}O-N ha^{–1} field. Despite relatively high emissions per surface area, the irrigation network is only a minor component of the total farm area, and indirect emissions from the irrigation system contribute ~2.4–4% of the total N_{2}O emissions and <0.02% of the applied N fertiliser.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Mitchell2016,
title = {The influence of above-ground residue input and incorporation on GHG fluxes and stable SOM formation in a sandy soil.},
author = {E. Mitchell and C. Scheer and D. W. Rowlings and R.T. Conant and P.R. Grace and M.F. Cotrufo and L. van Delden},
doi = {10.1016/j.soilbio.2016.07.008},
year = {2016},
date = {2016-07-20},
journal = {Soil Biology Biochemistry},
volume = {101},
pages = {104-113},
abstract = {Carbon sequestration in agricultural soils has been promoted as a means to reduce atmospheric concentrations of greenhouse gases (GHG) whilst improving soil productivity. Although there is broad agreement on practices that increase carbon (C) stocks, there is a lack of understanding on the stability of these gains and how changes in soil organic carbon (SOC) pools can influence GHG fluxes. We tracked the fate of above-ground residues into functionally different SOC pools and GHG fluxes using isotopically labelled residues (^{13}C and ^{15}N) over 12 months in a pasture soil in sub-tropical Australia. Agricultural residue management was simulated by: (1) altering the rate of residue input and, (2) mixing residue with topsoil. GHG fluxes were significantly greater at high residue input levels due to the priming of existing SOC and elevated N_{2}O losses, fuelled by a greater availability of labile substrate. There was evidence of an asymptotic relationship between C input and residue-derived C accumulation in stable soil C pools at higher input levels, indicating that the soil was reaching its protective capacity. Mixing of residues contributed to a 40% increase in GHG fluxes in comparison to surface applied treatment, most notably from residue-derived C and N. This can be attributed to (i) the physical disruption of soil, particularly that of aggregates, which changed the microenvironment stimulating microbial activity, and (ii) greater residue-soil contact. Greater residue-soil contact through mixing also contributed to a 2 fold increase in the residue-derived C recovered in the mineral soil with the majority (56%) in the active C pool. Over a 12 month period, C sequestration was outweighed by GHG fluxes at high rates of input and when residues were mixed with the topsoil. C sequestration policies and associated management approaches must be assessed holistically under a range of conditions and in the long-term to ensure that detrimental practices are not promoted.},
keywords = {Soil Biology and Biochemistry},
pubstate = {published},
tppubtype = {article}
}

@article{Migliorati2016,
title = {Comparison of grain yields and N_{2}O emissions on Oxisol and Vertisol soils in response to fertiliser N applied as urea or urea coated with the nitrification inhibitor 3,4-dimethylpyrazole phosphate},
author = {M De Antoni Migliorati and Mike Bell and David Lester and David W. Rowlings and Clemens Scheer and Daniele de Rosa and Peter R. Grace},
doi = {10.1071/SR15336},
year = {2016},
date = {2016-07-18},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {552-564},
abstract = {The potential for elevated nitrous oxide (N_{2}O) losses is high in subtropical cereal cropping systems in north-east Australia, where the fertiliser nitrogen (N) input is one single application at or before planting. The use of urea coated with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) has been reported to substantially decrease N_{2}O emissions and increase crop yields in humid, high-intensity rainfall environments. However, it is still uncertain whether this product is similarly effective in contrasting soil types in the cropping region of north-east Australia. In this study the grain yield response of sorghum (\textit{Sorghum bicolor} L. Moench) to rates of fertiliser N applied as urea or urea coated with DMPP were compared in crops grown on a Vertisol and an Oxisol in southern Queensland. Seasonal N_{2}O emissions were monitored on selected treatments for the duration of the cropping season and the early stages of a subsequent fallow period using a fully automated high-frequency greenhouse gas measuring system. On each soil the tested treatments included an unfertilised control (0 kg N ha^{–1}) and two fertilised treatments chosen on the basis of delivering at least 90% of seasonal potential grain yield (160 and 120 kg N ha^{–1} on the Vertisol and Oxisol respectively) or at a common (suboptimal) rate at each site (80 kg N ha^{–1}). During this study DMPP had a similar impact at both sites, clearly inhibiting nitrification for up to 8 weeks after fertiliser application. Despite the relatively dry seasonal conditions during most of the monitoring period, DMPP was effective in abating N_{2}O emissions on both soils and on average reduced seasonal N_{2}O emissions by 60% compared with conventional urea at fertiliser N rates equivalent to those producing 90% of site maximum grain yield. The significant abatement of N_{2}O emissions observed with DMPP, however, did not translate into significant yield gains or improvements in agronomic efficiencies of fertiliser N use. These results may be due to the relatively dry growing season conditions before the bulk of crop N acquisition, which limited the exposure of fertiliser N to large losses due to leaching and denitrification.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Riches2016,
title = {Mitigation of nitrous oxide emissions with nitrification inhibitors in temperate vegetable cropping in southern Australia},
author = {D. A. Riches and S. W. Mattner and R. Davies and I. J. Porter},
doi = {10.1071/SR15320},
year = {2016},
date = {2016-07-18},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {533-543},
abstract = {Intensive vegetable production in southern Australia is characterised by high inputs of nitrogen (N) fertiliser, water, and occasionally animal manures, which creates the potential for high nitrous oxide (N_{2}O) emissions. Three field experiments were conducted to investigate the effects of the nitrification inhibitors 3, 4-dimethylpyrazole phosphate (DMPP), 3-methyl pyrazole plus 1H-1,2,4 triazole (3MP+TZ), and dicyandiamide (DCD) on N_{2}O emissions and yields in broccoli (\textit{Brassica oleracea}), lettuce (\textit{Lactuca sativa}) and cauliflower (\textit{Brassica oleracea}) crops in southern Australia. The inhibitor treatments on fertilisers and poultry manure were compared with standard commercial practice for vegetable crops in this region, and N_{2}O emissions were measured using manual chambers through to harvest. Daily fluxes ranged from 0.81 g N_{2}O-N ha^{–1} day^{–1} for untreated soil to 11.65 g N_{2}O-N ha^{–1} day^{–1} for manure treated soil. Extrapolation of these results translate to annual emissions of 0.30 kg N_{2}O-N ha^{–1} year^{–1} to 4.24 kg N_{2}O-N ha^{–1} year^{–1}, respectively. Cumulative soil N_{2}O fluxes from the manure treatments were ~4-fold greater than the standard inorganic fertiliser program for a given crop. Nitrous oxide direct emission factors were in the range 0.02–0.16% for inorganic fertilisers and from 0.19% to 0.43% for poultry manure. The greatest decrease in N_{2}O emissions occurred when DMPP or a combination of 3MP+TZ were added to poultry manure (62% and 66% decrease, respectively). Decreases in N_{2}O emissions from nitrification inhibitors were smaller and less consistent when used with inorganic fertilisers, but DMPP decreased emissions in two out of three trials, with a maximum decrease of 32% observed in the broccoli trial. DCD proved ineffective for mitigating N_{2}O emissions in all trials.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Mielenz2016,
title = {Nitrous oxide emissions from grain production systems across a wide range of environmental conditions in eastern Australia},
author = {Henrike Mielenz and Peter J. Thorburn and Robert H. Harris and Sally J. Officer and Guangdi Li and G. D. Schwenke and Peter R. Grace},
doi = {10.1071/SR15376},
year = {2016},
date = {2016-07-18},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {659-674},
abstract = {Nitrous oxide (N_{2}O) emissions from Australian grain cropping systems are highly variable due to the large variations in soil and climate conditions and management practices under which crops are grown. Agricultural soils contribute 55% of national N_{2}O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N_{2}O emissions, yield and emissions intensity in a range of management practices in grain crops across eastern Australia with the Agricultural Production Systems sIMulator (APSIM). The model was initially evaluated against experiments conducted at six field sites across major grain-growing regions in eastern Australia. Measured yields for all crops used in the experiments (wheat, barley, sorghum, maize, cotton, canola and chickpea) and seasonal N_{2}O emissions were satisfactorily predicted with \textit{R}^{2} = 0.93 and \textit{R}^{2} = 0.91 respectively. As expected, N_{2}O emissions and emissions intensity increased with increasing nitrogen (N) fertiliser input, whereas crop yields increased until a yield plateau was reached at a site- and crop-specific N rate. The mitigation potential of splitting N fertiliser application depended on the climate conditions and was found to be relevant only in the southern grain-growing region, where most rainfall occurs during the cropping season. Growing grain legumes in rotation with cereal crops has great potential to reduce mineral N fertiliser requirements and so N_{2}O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N_{2}O mitigation.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Swarts2016,
title = {Benchmarking nitrous oxide emissions in deciduous tree cropping systems},
author = {Nigel Swarts and Kelvin Montagu and Garth Oliver and Liam Southam-Rogers and Marcus Hardie and Ross Corkrey and Gordon Rogers and Dugald Close},
doi = {10.1071/SR15326},
year = {2016},
date = {2016-07-12},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {500-511},
abstract = {Nitrous oxide (N_{2}O) emissions contribute 6% of the global warming effect and are derived from the activity of soil-based microorganisms involved in nitrification and denitrification processes. There is a paucity of greenhouse gas emissions data for Australia’s horticulture industry. In this study we investigated N_{2}O flux from two deciduous fruit tree crops, apples and cherries, in two predominant growing regions in eastern Australia, the Huon Valley in southern Tasmania (Lucaston – apples and Lower Longley – cherries), and high altitude northern New South Wales (Orange – apples and Young – cherries). Estimated from manual chamber measurements over a 12-month period, average daily emissions were very low ranging from 0.78 g N_{2}O-N ha^{–1} day^{–1} in the apple orchard at Lucaston to 1.86 g N_{2}O-N ha^{–1} day^{–1} in the cherry orchard in Lower Longley. Daily emissions were up to 50% higher in summer (maximum 5.27 g N_{2}O-N ha^{–1} day^{–1} at Lower Longley) than winter (maximum 2.47 g N_{2}O-N ha^{–1} day^{–1} at Young) across the four trial orchards. N_{2}O emissions were ~40% greater in the inter-row than the tree line for each orchard. Daily flux rates were used as a loss estimate for annual emissions, which ranged from 298 g N_{2}O-N ha^{–1} year^{–1} at Lucaston to 736 g N_{2}O-N ha^{–1} year^{–1} at Lower Longley. Emissions were poorly correlated with soil temperature, volumetric water content, water filled porosity, gravimetric water content and matric potential – with inconsistent patterns between sites, within the tree line and inter-row and between seasons. Stepwise linear regression models for the Lucaston site accounted for less than 10% of the variance in N_{2}O emissions, for which soil temperature was the strongest predictor. N_{2}O emissions in deciduous tree crops were among the lowest recorded for Australian agriculture, most likely due to low rates of N fertiliser, cool temperate growing conditions and highly efficient drip irrigation systems. We recommend that optimising nutrient use efficiency with improved drainage and a reduction in soil compaction in the inter-row will facilitate further mitigation of N_{2}O emissions.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Harris2016,
title = {Effect of nitrogen fertiliser management on soil mineral nitrogen, nitrous oxide losses, yield and nitrogen uptake of wheat growing in waterlogging-prone soils of south-eastern Australia},
author = {Robert H. Harris and Roger D. Armstrong and Ashley J. Wallace and Oxana N. Belyaeva},
doi = {doi.org/10.1071/SR15292},
year = {2016},
date = {2016-07-11},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {619-633},
abstract = {Some of the highest nitrous oxide (N_{2}O) emissions arising from Australian agriculture have been recorded in the high-rainfall zone (>650 mm) of south-western Victoria. Understanding the association between nitrogen (N) management, crop N uptake and gaseous losses is needed to reduce N_{2}O losses. Field experiments studied the effect of N-fertiliser management on N_{2}O emissions, crop N uptake and crop productivity at Hamilton and Tarrington in south-western Victoria. Management included five rates of urea-N fertiliser (0, 25, 50, 100 and 200 kg N/ha) topdressed at either mid-tillering or first-node growth stages of wheat development; urea-N deep-banded 10 cm below the seed at sowing; and urea coated with the nitrification inhibitor DMPP (3,4-dimethylpyrazole phosphate) was either topdressed or deep-banded. Pre-sowing soil profile chemical properties were determined before static chambers were installed to measure N_{2}O losses, accompanied by wheat dry matter, crop N uptake and grain yield and quality, to measure treatment differences. N_{2}O losses increased significantly (\textit{P} ≤ 0.10) where urea-N was deep-banded, resulting in a 2–2.5-fold increase in losses, compared with the nil N control. The high N_{2}O losses from deep-banding N appeared to result from winter waterlogging triggering gaseous or drainage losses before wheat reached peak growth and demand for N in spring. Despite the high losses from deep-banding urea-N, grain yields were largely unaffected by N management, except at Hamilton in 2012, where topdressed wheat growing in a soil with large reserves of NO_{3}^{–}-N, and later experiencing post-anthesis water deficit resulted in a negative grain yield response. All sites had high concentrations of soil organic carbon (>2.8%) and the potential for large amounts of N mineralisation throughout the growing season to supplement low N fertiliser recovery. However, topdressed urea-N resulted in significant enrichment of crop tissue (\textit{P} ≤ 0.004) and associated positive response in grain protein compared with the deep banded and nil N treatments. 3,4-Dimethylpyrazole phosphate (DMPP)-coated urea provided no additional benefit to crop yield over conventional urea N. Our study highlighted the importance of synchronising N supply with peak crop N demand to encourage greater synthetic N uptake and mitigation of N_{2}O losses.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Wang2016,
title = {Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea},
author = {Weijin Wang and Glen Park and Steven Reeves and Megan Zahmel and Marijke Heenan and Barry Salter},
doi = {10.1071/SR15314},
year = {2016},
date = {2016-07-11},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {572-584},
abstract = {Nitrous oxide (N_{2}O) emissions from sugarcane cropped soils are usually high compared with those from other arable lands. Nitrogen-efficient management strategies are needed to mitigate N_{2}O emissions from sugarcane farming whilst maintaining productivity and profitability. A year-long field experiment was conducted in wet tropical Australia to assess the efficacy of polymer-coated urea (PCU) and nitrification inhibitor (3,4-dimethylpyrazole phosphate)-coated urea (NICU). Emissions of N_{2}O were measured using manual and automatic gas sampling chambers in combination. The nitrogen (N) release from PCU continued for >5–6 months, and lower soil NO_{3}^{–} contents were recorded for ≥ 3 months in the NICU treatments compared with the conventional urea treatments. The annual cumulative N_{2}O emissions were high, amounting to 11.4–18.2 kg N_{2}O-N ha^{–1}. In contrast to findings in most other cropping systems, there were no significant differences in annual N_{2}O emissions between treatments with different urea formulations and application rates (0, 100 and 140 kg N ha^{–1}). Daily variation in N_{2}O emissions at this site was driven predominantly by rainfall. Urea formulations did not significantly affect sugarcane or sugar yield at the same N application rate. Decreasing fertiliser application rate from the recommended 140 kg N ha^{–1} to 100 kg N ha^{–1} led to a decrease in sugar yield by 1.3 t ha^{–1} and 2.2 t ha^{–1} for the conventional urea and PCU treatments, respectively, but no yield loss occurred for the NICU treatment. Crop N uptake also declined at the reduced N application rate with conventional urea, but not with the PCU and NICU. These results demonstrated that substituting NICU for conventional urea may substantially decrease fertiliser N application from the normal recommended rates whilst causing no yield loss or N deficiency to the crop. Further studies are required to investigate the optimal integrated fertiliser management strategies for sugarcane production, particularly choice of products and application time and rates, in relation to site and seasonal conditions.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Scheer2016,
title = {Effect of enhanced efficiency fertilisers on nitrous oxide emissions in a sub-tropical cereal cropping system},
author = {Clemens Scheer and David W. Rowlings and M De Antoni Migliorati and David W. Lester and Mike J. Bell and Peter R. Grace},
doi = {10.1071/SR15332},
year = {2016},
date = {2016-07-06},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {544-551},
abstract = {To meet the global food demand in the coming decades, crop yields per unit area must increase. This can only be achieved by a further intensification of existing cropping systems and will require even higher inputs of N fertilisers, which may result in increased losses of nitrous oxide (N_{2}O) from cropped soils. Enhanced efficiency fertilisers (EEFs) have been promoted as a potential strategy to mitigate N_{2}O emissions and improve nitrogen use efficiency (NUE) in cereal cropping systems. However, only limited data are currently available on the use of different EEF products in sub-tropical cereal systems. A field experiment was conducted to investigate the effect of three different EEFs on N_{2}O emissions, NUE and yield in a sub-tropical summer cereal cropping system in Australia. Over an entire year soil N_{2}O fluxes were monitored continuously (3 h sampling frequency) with a fully-automated measuring system. The experimental site was fertilised with different nitrogen (N) fertilisers applied at 170 kg N ha^{–1}, namely conventional urea (Urea), urea with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP), polymer-coated urea (PCU), and urea with the nitrification inhibitor nitrapyrin (Nitrapyrin). Nitrous oxide emissions were highly episodic and mainly controlled by heavy rainfall events within two months of planting and fertiliser N application. Annual N_{2}O emissions in the four treatments amounted to 2.31, 0.40, 0.69 and 1.58 kg N_{2}O-N ha^{–1} year^{–1} for Urea, DMPP, PCU and Nitrapyrin treatments, respectively, while unfertilised plots produced an average of 0.16 kg N_{2}O-N ha^{–1} year^{–1}. Two of the tested products (DMPP and PCU) were found to be highly effective, decreasing annual N_{2}O losses by 83% and 70%, respectively, but did not affect yield or NUE. This study shows that EEFs have a high potential to decrease N_{2}O emissions from sub-tropical cereal cropping systems. More research is needed to assess if the increased costs of EEFs can be compensated by lower fertiliser application rates and/or yield increases.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}

@article{Suter2016,
title = {Influence of enhanced efficiency fertilisation techniques on nitrous oxide emissions and productivity response from urea in a temperate Australian ryegrass pasture},
author = {H. C. Suter and H. Sultana and R. Davies and C. Walker and D. Chen},
doi = {10.1071/SR15317},
year = {2016},
date = {2016-07-06},
journal = {Soil Research},
volume = {54},
number = {5},
pages = {523-532},
abstract = {The effect of a nitrification inhibitor on nitrous oxide (N_{2}O) emissions across seasons, the effect of a urease inhibitor and a fine particle spray (both targeting ammonia (NH_{3}) loss) on N_{2}O emissions, and the potential for productivity benefits and efficiencies by using these enhanced efficiency fertilisers (EEFs) were investigated in temperate pastures. The study compared three treatments over an eight month period (April to December 2010): (1) urea (U), (2) urea with a nitrification inhibitor (3,4-dimethylpyrazole phosphate) (DMPP), and (3) urea with a urease inhibitor (N-(\textit{n}-butyl) thiophosphoric triamide (NBTPT)) (GU). In autumn, when NH_{3} loss was predicted to be high, the effect of urea applied as a fine particle spray (containing urea, NBTPT and gibberellic acid (10 g ha^{–1})) (FPA) on N_{2}O emissions and productivity was determined.
The effect of a nitrification inhibitor on nitrous oxide (N_{2}O) emissions across seasons, the effect of a urease inhibitor and a fine particle spray (both targeting ammonia (NH_{3}) loss) on N_{2}O emissions, and the potential for productivity benefits and efficiencies by using these enhanced efficiency fertilisers (EEFs) were investigated in temperate pastures. The study compared three treatments over an eight month period (April to December 2010): (1) urea (U), (2) urea with a nitrification inhibitor (3,4-dimethylpyrazole phosphate) (DMPP), and (3) urea with a urease inhibitor (N-(\textit{n}-butyl) thiophosphoric triamide (NBTPT)) (GU). In autumn, when NH_{3} loss was predicted to be high, the effect of urea applied as a fine particle spray (containing urea, NBTPT and gibberellic acid (10 g ha^{–1})) (FPA) on N_{2}O emissions and productivity was determined.},
keywords = {Soil Research 54},
pubstate = {published},
tppubtype = {article}
}