Soil N2O emissions under N2-fixing legumes and N-fertilised canola: A reappraisal of emissions factor calculations

Schwenke, Graeme; Herridge, D. F.; Scheer, Clemens; Rowlings, David; Haigh, Bruce M.; McMullen, K. Guy

doi:10.1016/j.agee.2015.01.017

Cited by 71 publications

(44 citation statements)

References 33 publications

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“…Higher annual N 2 O emissions were also obtained with automatic chambers than manual chambers in a N-fertilised canola crop, while similar results were recorded with the different methods in a parallel, unfertilised chickpea crop (Schwenke et al 2015). During the first two and half months in the present study (Fig.…”

Section: Automatic Versus Manual Chamber Measurementssupporting

confidence: 69%

Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

et al. 2016

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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.

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Section: Automatic Versus Manual Chamber Measurementssupporting

confidence: 69%

Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

et al. 2016

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“…High soil temperature, coupled with episodic summer rainfall events, stimulated soil microbial activity, resulting in N mineralisation from crop residues and soil organic matter with concomitant increased N 2 O emissions. The significantly higher soil mineral N under the 100 kg N/ha treatment, particularly during the fallow period, was either due to over-supply of fertiliser N under that treatment, or rapid breakdown of the N-rich canola residues (Schwenke et al 2015). Over the 365-day measurement period, applying 100 kg N/ha increased the annual N 2 O emission by 28% compared with the nil-N treatment, most probably due to increased soil nitrification and denitrification processes resulting from the higher soil N status (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…There is ample evidence that increased N application increases N 2 O emission in many environments (Wang et al 2011;Harris et al 2013;Schwenke et al 2015). In the current study, the N 2 O emission increased significantly immediately after fertiliser N was top-dressed compared with the nil-N treatment (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Increasing application rates of nitrogen (N) fertiliser has been previously shown to increase N 2 O emissions in broadacre cropping systems across a range of environments (Dalal et al 2003;Harris et al 2013;Schwenke and Haigh 2015), attributable to higher availability of N vulnerable to gaseous loss and to an imbalance between N availability in the soil and demand by the crop. Tillage is known to elevate levels of plantavailable soil N due to mineralisation of soil organic matter.…”

Section: Introductionmentioning

confidence: 99%

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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

Li¹,

Conyers²,

Schwenke

et al. 2016

Soil Res.

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Abstract. Dryland cereal production systems of south-eastern Australia require viable options for reducing nitrous oxide (N 2 O) 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 541 mm and the incidence of summer rainfall is episodic and unreliable. The objectives of the experiment were to investigate whether (i) tillage increases N 2 O emissions and (ii) nitrogen (N) application can improve productivity without increasing N 2 O 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 100 kg N/ha) as the subplot, replicated three times. This paper reports high resolution N 2 O emission data under a canola crop. The daily N 2 O emission rate averaged 0.55 g N 2 O-N/ha. day, ranging between -0.81 and 6.71 g N 2 O-N/ha.day. The annual cumulative N 2 O-N emitted was 175.6 and 224.3 g N 2 O-N/ha under 0 and 100 kg N/ha treatments respectively. There was no evidence to support the first hypothesis that tillage increases N 2 O 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 N 2 O emissions, but did not increase crop production at this site.

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“…The array of values reflects, among other factors, rate of fertiliser N, crop type, tillage practice, stubble management, soil texture, soil pH, and environmentparticularly rainfall and temperature (Barker-Reid et al 2005;Barton et al 2008Barton et al , 2010Barton et al , 2013Li et al 2008;Officer et al 2010;Wang et al 2011;Schwenke et al 2015). An analysis of Australian work in which conservation tillage was used indicates an overall average EF of 0.28% from a range 0.01-0.77%.…”

Section: Introductionmentioning

confidence: 99%

Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

et al. 2016

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Abstract. The northern Australian grains industry relies on nitrogen (N) fertiliser to optimise yield and protein, but N fertiliser can increase soil fluxes of nitrous oxide (N 2 O) and methane (CH 4 ). We measured soil N 2 O and CH 4 fluxes associated with wheat (Triticum aestivum) and barley (Hordeum vulgare) using automated (Expts 1, 3) and manual chambers (Expts 2, 4, 5). Experiments were conducted on subtropical Vertosol soils fertilised with N rates of 0-160 kg N ha -1 .In Expt 1 (2010), intense rainfall for a month before and after sowing elevated N 2 O emissions from N-fertilised (80 kg N ha -1 ) wheat, with 417 g N 2 O-N ha -1 emitted compared with 80 g N 2 O-N ha -1 for non-fertilised wheat. Once crop N uptake reduced soil mineral N, there was no further treatment difference in N 2 O. Expt 2 (2010) showed similar results, however, the reduced sampling frequency using manual chambers gave a lower cumulative N 2 O. By contrast, very low rainfall before and for several months after sowing Expt 3 (2011) resulted in no difference in N 2 O emissions between N-fertilised and non-fertilised barley. N 2 O emission factors were 0.42, 0.20 and -0.02 for Expts 1, 2 and 3, respectively. In Expts 4 and 5 (2011), N 2 O emissions increased with increasing rate of N fertiliser. Emissions were reduced by 45% when the N fertiliser was applied in a 50 : 50 split between sowing and mid-tillering, or by 70% when urea was applied with the nitrification inhibitor 3,4-dimethylpyrazole-phosphate.Methane fluxes were typically small and mostly negative in all experiments, especially in dry soils. Cumulative CH 4 uptake ranged from 242 to 435 g CH 4 -C ha -1 year -1 , with no effect of N fertiliser treatment. Considered in terms of CO 2 equivalents, soil CH 4 uptake offset 8-56% of soil N 2 O emissions, with larger offsets occurring in non-N-fertilised soils.The first few months from N fertiliser application to the period of rapid crop N uptake pose the main risk for N 2 O losses from rainfed cereal cropping on subtropical Vertosols, but the realisation of this risk is dependent on rainfall. Strategies that reduce the soil mineral N pool during this time can reduce the risk of N 2 O loss.

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Soil N2O emissions under N2-fixing legumes and N-fertilised canola: A reappraisal of emissions factor calculations

Cited by 71 publications

References 33 publications

Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

Nitrous oxide emission and fertiliser nitrogen efficiency in a tropical sugarcane cropping system applied with different formulations of urea

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

Greenhouse gas (N2O and CH4) fluxes under nitrogen-fertilised dryland wheat and barley on subtropical Vertosols: risk, rainfall and alternatives

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