Response of soil nitrous oxide flux to nitrogen fertiliser application and legume rotation in a semi-arid climate, identified by smoothing spline models

Although large areas of semi-arid land are extensively cropped, few studies have investigated the effect of nitrogen (N) fertiliser on nitrous oxide (N2O) emissions in these regions (Galbally et al. 2010). These emissions need to be measured in order to estimate N losses and calculate national greenhouse gas inventories. We examined the effect of different agronomic management practices applied to wheat (Triticum aestivum) grown on an alkaline Vertosol in south-eastern Australia on N2O emissions. In 2007, N2O emissions were measured over 12 months, during which N fertiliser (urea) was applied at sowing or N fertiliser plus supplementary irrigation (50 mm) was applied during the vegetative stage and compared with a treatment of no N fertiliser or irrigation. In a second experiment (2008), the effect of source of N on N2O emissions was examined. Wheat was grown on plots where either a pulse (field peas, Pisum sativum) or pasture legume (barrel medic, Medicago truncatula) crop had been sown in the previous season compared with a non-legume crop (canola, Brassica napus). To account for the N supplied by the legume phase, N fertiliser (50 kg N ha–1 as urea) was applied only to the wheat in the plots previously sown to canola. Fluxes of N2O were measured on a sub-daily basis (up to 16 measurements per chamber) by using automated chamber enclosures and a tuneable diode laser, and treatment differences were evaluated by a linear mixed model including cubic smoothing splines. Fluxes were low and highly variable, ranging from –3 to 28 ng N2O-N m–2 s–1. The application of N fertiliser at sowing increased N2O emissions for ~2 months after the fertiliser was applied. Applying irrigation (50 mm) during the vegetative growth stage produced a temporary (~1-week) but non-significant increase in N2O emissions compared with plots that received N fertiliser at sowing but were not irrigated. Including a legume in the rotation significantly increased soil inorganic N at sowing of the following wheat crop by 38 kg N ha–1 (field peas) or 57 kg ha–1 (barrel medic) compared with a canola crop. However, N2O emissions were greater in wheat plots where N fertiliser was applied than where wheat was sown into legume plots where no N fertiliser was applied. Over the 2 years of the field study, N2O emissions attributed to fertiliser ranged from 41 to 111 g N2O-N ha–1, and averaged of 75 g N2O-N ha–1 or 0.15% of the applied N fertiliser. Our findings confirm that the proportion of N fertiliser emitted as N2O from rainfed grain crops grown in Australian semi-arid regions is less than the international average of 1.0%.

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The effectiveness of nitrification inhibitor application on grain yield and quality, fertiliser nitrogen recovery and soil nitrous oxide emissions in a legume–wheat rotation under elevated carbon dioxide (FACE)

Soil Research ◽

10.1071/sr16371 ◽

2018 ◽

Vol 56 (2) ◽

pp. 145

Author(s):

Humaira Sultana ◽

Helen C. Suter ◽

Roger Armstrong ◽

Marc E. Nicolas ◽

Deli Chen

Keyword(s):

Carbon Dioxide ◽

Nitrous Oxide ◽

Copper Concentration ◽

Nitrification Inhibitor ◽

Elevated Carbon Dioxide ◽

Wheat Crop ◽

N2o Emissions ◽

N Concentration ◽

Supplementary Irrigation ◽

The Impact

Managing nitrogen (N) supply to better match crop demand and reduce losses will be an important goal under future predicted elevated carbon dioxide (e[CO2]) conditions. This study comprised two Free-Air Carbon dioxide Enrichment (FACE) experiments conducted in southern Australia in 2011. The first experiment (Exp-1) was a field experiment that investigated the impact of a nitrification inhibitor (NI), 3,4-dimethylpyrazole phosphate (DMPP), and supplementary irrigation on utilisation of legume (field pea) residual N by a wheat crop and soil nitrous oxide (N2O) emissions. The second experiment (Exp-2) used 15N techniques in soil cores to investigate the impact of DMPP on recovery of fertiliser N. In Exp-1, grain N concentration increased (by 12%, P < 0.001) with NI application compared with no NI application, irrespective of CO2 concentration ([CO2]) and supplementary irrigation. With NI application the grain N harvest index increased under e[CO2] (82%) compared with a[CO2] (79%). Applying the NI compensated for decreased grain copper concentration observed under e[CO2] conditions. NI had minimal effect on soil N2O emissions in the wheat crop regardless of [CO2]. In Exp-2, 65% (±1 standard error, n = 15) of the applied N fertiliser was recovered in the aboveground plant, irrespective of NI use. The use of a NI in a cereal–legume rotation may help to increase grain N concentration, increase the mobilisation of N towards the grain under e[CO2], and may also help to compensate for decreases in grain copper concentration under e[CO2]. However, use of a NI may not provide additional benefit for productivity or efficiency of N utilisation.

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Does 3,4-dimethylpyrazole phosphate or N-(n-butyl) thiophosphoric triamide reduce nitrous oxide emissions from a rain-fed cropping system?

Soil Research ◽

10.1071/sr17219 ◽

2018 ◽

Vol 56 (3) ◽

pp. 296 ◽

Cited By ~ 4

Author(s):

Guangdi D. Li ◽

Graeme D. Schwenke ◽

Richard C. Hayes ◽

Hongtao Xing ◽

Adam J. Lowrie ◽

...

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Crop Yields ◽

Cropping System ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

Wheat Crop ◽

N2o Emissions ◽

Urease Inhibitors ◽

Eastern Australia

Nitrification and urease inhibitors have been used to reduce nitrous oxide (N2O) emissions and increase nitrogen use efficiency in many agricultural systems. However, their agronomic benefits, such as the improvement of grain yield, is uncertain. A two-year field experiment was conducted to (1) investigate whether the use of 3,4-dimethylpyrazole phosphate (DMPP) or N-(n-butyl) thiophosphoric triamide (NBPT) can reduce N2O emissions and increase grain yield and (2) explore the financial benefit of using DMPP or NBPT in a rain-fed cropping system in south-eastern Australia. The experiment was conducted at Wagga Wagga, New South Wales, Australia with wheat (Triticum aestivum L.) in 2012 and canola (Brassica napus L.) in 2013. Results showed that urea coated with DMPP reduced the cumulative N2O emission by 34% for a wheat crop in 2012 (P < 0.05) and by 62% for a canola crop in 2013 (P < 0.05) compared with normal urea, but urea coated NBPT had no effect on N2O emission for the wheat crop in 2012. Neither nitrification nor urease inhibitors increased crop yields because the low rainfall experienced led to little potential for gross N loss through denitrification, leaching or volatilisation pathways. In such dry years, only government or other financial incentives for N2O mitigation would make the use of DMPP with applied N economically viable.

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Influence of elevated atmospheric carbon dioxide and supplementary irrigation on greenhouse gas emissions from a spring wheat crop in southern Australia

The Journal of Agricultural Science ◽

10.1017/s002185961200055x ◽

2012 ◽

Vol 151 (2) ◽

pp. 201-208 ◽

Cited By ~ 6

Author(s):

S. K. LAM ◽

D. CHEN ◽

R. NORTON ◽

R. ARMSTRONG ◽

A. R. MOSIER

Keyword(s):

Carbon Dioxide ◽

Greenhouse Gas ◽

Spring Wheat ◽

Cropping Systems ◽

Vegetative Stage ◽

Wheat Crop ◽

Growth Stages ◽

Soil System ◽

Supplementary Irrigation ◽

Semi Arid

SUMMARYThe effect of elevated carbon dioxide (CO2) concentration on greenhouse gas (GHG) emission from semi-arid cropping systems is poorly understood. Closed static chambers were used to measure the fluxes of nitrous oxide (N2O), CO2and methane (CH4) from a spring wheat (Triticum aestivumL. cv. Yitpi) crop-soil system at the Australian grains free-air carbon dioxide enrichment (AGFACE) facility at Horsham in southern Australia in 2009. The targeted atmospheric CO2concentrations (hereafter CO2concentration is abbreviated as [CO2]) were 390 (ambient) and 550 (elevated) μmol/mol for both rainfed and supplementary irrigated treatments. Gas measurements were conducted at five key growth stages of wheat. Elevated [CO2] increased the emission of N2O and CO2by 108 and 29%, respectively, with changes being greater during the wheat vegetative stage. Supplementary irrigation reduced N2O emission by 36%, suggesting that N2O was reduced to N2in the denitrification process. Irrigation increased CO2flux by 26% at ambient [CO2] but not at elevated [CO2], and had no impact on CH4flux. The present results suggest that under future atmospheric [CO2], agricultural GHG emissions at the vegetative stage may be higher and irrigation is likely to reduce the emissions from semi-arid cropping systems.

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Tillage does not increase nitrous oxide emissions under dryland canola (Brassica napus L.) in a semiarid environment of south-eastern Australia

Soil Research ◽

10.1071/sr15289 ◽

2016 ◽

Vol 54 (5) ◽

pp. 512 ◽

Cited By ~ 9

Author(s):

Guangdi D. Li ◽

Mark K. Conyers ◽

Graeme D. Schwenke ◽

Richard C. Hayes ◽

De Li Liu ◽

...

Keyword(s):

Nitrous Oxide ◽

Brassica Napus ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

Annual Rainfall ◽

N2o Emissions ◽

Brassica Napus L ◽

South Eastern ◽

Eastern Australia ◽

South Eastern Australia

Dryland cereal production systems of south-eastern Australia require viable options for reducing nitrous oxide (N2O) emissions without compromising productivity and profitability. A 4-year rotational experiment with wheat (Triticum aestivum L.)–canola (Brassica napus L.)–grain legumes–wheat in sequence was established at Wagga Wagga, NSW, Australia, in a semiarid Mediterranean-type environment where long-term average annual rainfall is 541mm and the incidence of summer rainfall is episodic and unreliable. The objectives of the experiment were to investigate whether (i) tillage increases N2O emissions and (ii) nitrogen (N) application can improve productivity without increasing N2O emissions. The base experimental design for each crop phase was a split-plot design with tillage treatment (tilled versus no-till) as the whole plot, and N fertiliser rate (0, 25, 50 and 100kgN/ha) as the subplot, replicated three times. This paper reports high resolution N2O emission data under a canola crop. The daily N2O emission rate averaged 0.55g N2O-N/ha.day, ranging between –0.81 and 6.71g N2O-N/ha.day. The annual cumulative N2O-N emitted was 175.6 and 224.3g N2O-N/ha under 0 and 100kgN/ha treatments respectively. There was no evidence to support the first hypothesis that tillage increases N2O emissions, a result which may give farmers more confidence to use tillage strategically to manage weeds and diseases where necessary. However, increasing N fertiliser rate tended to increase N2O emissions, but did not increase crop production at this site.

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Can legume species, crop residue management or no-till mitigate nitrous oxide emissions from a legume-wheat crop rotation in a semi-arid environment?

Soil and Tillage Research ◽

10.1016/j.still.2020.104910 ◽

2021 ◽

Vol 209 ◽

pp. 104910

Author(s):

Guangdi D. Li ◽

Graeme D. Schwenke ◽

Richard C. Hayes ◽

Adam J. Lowrie ◽

Richard J. Lowrie ◽

...

Keyword(s):

Nitrous Oxide ◽

Crop Rotation ◽

Crop Residue ◽

Arid Environment ◽

Residue Management ◽

Nitrous Oxide Emissions ◽

Wheat Crop ◽

Legume Species ◽

No Till ◽

Semi Arid

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Cradle-to-farmgate greenhouse gas emissions for 2-year wheat monoculture and break crop–wheat sequences in south-eastern Australia

Crop and Pasture Science ◽

10.1071/cp15260 ◽

2016 ◽

Vol 67 (8) ◽

pp. 812 ◽

Cited By ~ 10

Author(s):

Philippa M. Brock ◽

Sally Muir ◽

David F. Herridge ◽

Aaron Simmons

Keyword(s):

Ghg Emissions ◽

Wheat Crop ◽

Gross Margin ◽

Life Cycle Assessment Methodology ◽

Soil C ◽

South Eastern ◽

Field Peas ◽

Eastern Australia ◽

Rainfed Wheat ◽

The Impact

We used life cycle assessment methodology to determine the cradle-to-farmgate GHG emissions for rainfed wheat grown in monoculture or in sequence with the break crops canola (Brassica napus) and field peas (Pisum sativum), and for the break crops, in the south-eastern grains region of Australia. Total GHG emissions were 225 kg carbon dioxide equivalents (CO2-e)/t grain for a 3 t/ha wheat crop following wheat, compared with 199 and 172 kg CO2-e/t for wheat following canola and field peas, respectively. On an area basis, calculated emissions were 676, 677 and 586 kg CO2-e/ha for wheat following wheat, canola and field peas, respectively. Highest emissions were associated with the production and transport of fertilisers (23–28% of total GHG emissions) and their use in the field (16–23% of total GHG emissions). Production, transport and use of lime accounted for an additional 19–21% of total GHG emissions. The lower emissions for wheat after break crops were associated with higher yields, improved use of fertiliser nitrogen (N) and reduced fertiliser N inputs in the case of wheat after field peas. Emissions of GHG for the production and harvesting of canola were calculated at 841 kg CO2-e/ha, equivalent to 420 kg CO2-e/t grain. Those of field peas were 530 kg CO2-e/ha, equivalent to 294 kg CO2-e/t grain. When the gross margin returns for the crops were considered together with their GHG emissions, the field pea–wheat sequence had the highest value per unit emissions, at AU$787/t CO2-e, followed by wheat–wheat ($703/t CO2-e) and canola–wheat ($696/t CO2-e). Uncertainties associated with emissions factor values for fertiliser N, legume-fixed N and mineralised soil organic matter N are discussed, together with the potentially high C cost of legume N2 fixation and the impact of relatively small changes in soil C during grain cropping either to offset all or most pre- and on-farm GHG emissions or to add to them.

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Gaseous nitrogen losses from pig slurry fertilisation: can they be reduced with additives in a wheat crop?

Spanish Journal of Agricultural Research ◽

10.5424/sjar/2021193-17271 ◽

2021 ◽

Vol 19 (3) ◽

pp. e0302

Author(s):

Noemí Mateo-Marín ◽

Ramón Isla ◽

Dolores Quílez

Keyword(s):

Nitrous Oxide ◽

Nitrification Inhibitor ◽

Nitrous Oxide Emissions ◽

Wheat Crop ◽

N2o Emissions ◽

Pig Slurry ◽

Gaseous Nitrogen ◽

N Losses ◽

Ammonia Volatilisation ◽

Irrigated Wheat

Aim of the study: The use of pig slurry as fertiliser is associated with gaseous nitrogen (N) losses, especially ammonia (NH3) and nitrous oxide (N2O), leading to environmental problems and a reduction of its fertiliser value. This study evaluates, in an irrigated wheat crop, the effect of different additives mixed with pig slurry to decrease NH3 and N2O losses.Area of study: Middle Ebro valley, SpainMaterials and methods: The treatments were: i) non-N-fertilised control, ii) pig slurry (PS), iii) pig slurry with the urease inhibitor monocarbamide dihydrogen sulphate (PS-UI), iv) pig slurry with a microbial activator in development (PS-A), and v) pig slurry with the nitrification inhibitor 3,4-dimethylpyrazole phosphate (PS-NI). Pig slurry was applied at a target rate of 120 kg NH4+-N ha-1. Ammonia volatilisation was measured using semi-opened static chambers after treatments application at presowing 2016 and side-dressing 2017. Nitrous oxide emissions were measured using static closed chambers after treatments application at the 2017 and 2018 side-dressing.Main results: Ammonia volatilisation was estimated to be 7-9% and 19-23% of NH4+-N applied after presowing and side-dressing applications, respectively. Additives were not able to reduce NH3 emissions in any application moment. PS-NI was the only treatment being effective in reducing N2O emissions, 70% respect to those in PS treatment. Crop yield parameters were not affected by the application of the additives because of the no effect of additives controlling NH3 losses and the low contribution of N2O losses to the N balance (<1 kg N2O-N ha-1).Research highlights: The use of 3,4-dimethylpyrazole phosphate would be recommended from an environmental perspective, although without grain yield benefits.

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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

Soil Research ◽

10.1071/sr15292 ◽

2016 ◽

Vol 54 (5) ◽

pp. 619 ◽

Cited By ~ 8

Author(s):

Robert H. Harris ◽

Roger D. Armstrong ◽

Ashley J. Wallace ◽

Oxana N. Belyaeva

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

N Uptake ◽

Yield Response ◽

Growth Stages ◽

N2o Emissions ◽

Eastern Australia ◽

Crop N Uptake ◽

Western Victoria ◽

N Management

Some of the highest nitrous oxide (N2O) emissions arising from Australian agriculture have been recorded in the high-rainfall zone (>650mm) of south-western Victoria. Understanding the association between nitrogen (N) management, crop N uptake and gaseous losses is needed to reduce N2O losses. Field experiments studied the effect of N-fertiliser management on N2O 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 200kgN/ha) topdressed at either mid-tillering or first-node growth stages of wheat development; urea-N deep-banded 10cm 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 N2O losses, accompanied by wheat dry matter, crop N uptake and grain yield and quality, to measure treatment differences. N2O losses increased significantly (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 N2O 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 NO3–-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 (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 N2O losses.

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Benchmarking nitrous oxide emissions in deciduous tree cropping systems

Soil Research ◽

10.1071/sr15326 ◽

2016 ◽

Vol 54 (5) ◽

pp. 500 ◽

Cited By ~ 7

Author(s):

Nigel Swarts ◽

Kelvin Montagu ◽

Garth Oliver ◽

Liam Southam-Rogers ◽

Marcus Hardie ◽

...

Keyword(s):

Nitrous Oxide ◽

Soil Temperature ◽

Water Content ◽

Nutrient Use Efficiency ◽

Nitrous Oxide Emissions ◽

Deciduous Tree ◽

N2o Emissions ◽

Tree Line ◽

Tree Crops ◽

Eastern Australia

Nitrous oxide (N2O) 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 N2O 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 0.78gN2O-Nha–1day–1 in the apple orchard at Lucaston to 1.86gN2O-Nha–1day–1 in the cherry orchard in Lower Longley. Daily emissions were up to 50% higher in summer (maximum 5.27gN2O-Nha–1day–1 at Lower Longley) than winter (maximum 2.47gN2O-Nha–1day–1 at Young) across the four trial orchards. N2O 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 298gN2O-Nha–1year–1 at Lucaston to 736gN2O-Nha–1year–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 N2O emissions, for which soil temperature was the strongest predictor. N2O 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 N2O emissions.

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Nitrous oxide emissions from grain production systems across a wide range of environmental conditions in eastern Australia

Soil Research ◽

10.1071/sr15376 ◽

2016 ◽

Vol 54 (5) ◽

pp. 659 ◽

Cited By ~ 6

Author(s):

Henrike Mielenz ◽

Peter J. Thorburn ◽

Robert H. Harris ◽

Sally J. Officer ◽

Guangdi Li ◽

...

Keyword(s):

Nitrous Oxide ◽

Management Practices ◽

Crop Yields ◽

Production Systems ◽

Nitrous Oxide Emissions ◽

N2o Emissions ◽

Climate Conditions ◽

Eastern Australia ◽

Wide Range ◽

Emissions Intensity

Nitrous oxide (N2O) 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 N2O emissions, and therefore mitigation of these emissions is important. In the present study, we explored N2O 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 N2O emissions were satisfactorily predicted with R2=0.93 and R2=0.91 respectively. As expected, N2O 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 N2O emissions. In general, N management strategies that maximise yields and increase N use efficiency showed the greatest promise for N2O mitigation.

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