Options for reducing soil nitrous oxide emissions in the NSW dryland grains industry

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1 Options for reducing soil nitrous oxide emissions in the NSW dryland grains industry Graeme Schwenke (northern NSW) Guangdi Li (southern NSW) De Li Liu (simulation modelling) NSW Department of Primary Industries

Acknowledgments Tamworth Agricultural Institute, Wagga Wagga Agricultural Institute, Liverpool Plains Field Station, Ian Carter Bruce Haigh, Annabelle McPherson, Bill Keene, Peter Sanson, Tara Burns,

2 Acknowledgments Tamworth Agricultural Institute, Wagga Wagga Agricultural Institute, Liverpool Plains Field Station, Ian Carter Bruce Haigh, Annabelle McPherson, Bill Keene, Peter Sanson, Tara Burns, Mandy Holland, Wayne McPherson, Kamal Hossain, Helen Squires, Nicole Carrigan, Pete Formann, Jan Hosking, Steve Morphett, Jim Perfrement, Pete Perfrement, Pat Mortell, Matt Gardner, Rick Graham, Steve Kimber, Brad Keen, and Leanne Lisle (UNE). Adam Lowrie, Richard Lowrie, Graeme Poile, Albert Oates, Binbin Xu, Vince van der Rijt, Sarah Bond and Kare Maihemuti. John Finlayson, Muhuddin Anwar, Yuchuan Ma, Bin Wang and Changsheng Li, Yong Li, Jianmin Lin. Peter Grace, Clemens Scheer, Dave Rowlings, Christian Brunk

Project Objectives Compare options that reduce N 2 O emissions and increase N use efficiency from northern and southern NSW dryland grains cropping Options included: optimise N rate applied, split

3 Project Objectives Compare options that reduce N 2 O emissions and increase N use efficiency from northern and southern NSW dryland grains cropping Options included: optimise N rate applied, split application of fertiliser N, use of N fertiliser containing inhibitors, substitution of fertiliser N with legume-derived N Validation of process-based biogeochemistry models for N 2 O emitted from dryland grain cropping trials. Simulate net greenhouse gas emissions under different agronomic practices using current and projected future climate scenarios

Northern NSW Year 1 N rate response N 2 O rate response?

O-N/ha) 1000 200 kg N/ha 120 kg N/ha 40 kg N/ha 0 kg

Average temperature ( o C) 0 90 80 70 10/12 11/12 12/12

kg N/ha 60 200 kg N/ha 50 40 30 20 10 Date 0 10/12

4 Northern NSW Year 1 N rate response N 2 O rate response? 0 kg N/ha 40 kg N/ha Cumulative N 2 O emissions (g N 2 O-N/ha) kg N/ha 120 kg N/ha 40 kg N/ha 0 kg N/ha Daily rainfall (mm) Voumetric soil water (%) Average temperature ( o C) /12 11/12 12/12 1/13 2/13 3/13 4/13 5/13 6/13 7/13 8/13 9/13 10/ kg N/ha kg N/ha Date 0 10/12 11/12 12/12 1/13 2/13 3/13 4/13 5/13 6/13 7/13 8/13 9/13 10/13 Date

5 Northern NSW Year 2 How to delay soil nitrate availability: nitrification inhibitor or late-apply N? 2500 Gross margin ($/ha) Cumulative N 2 O emissions (g N 2 O-N/ha) Urea 100 kg N/ha (booting) Entec 100 kg N/ha (sowing) Urea 100 kg N/ha (sowing) 0 kg N/ha N (booting) harvest N (sowing) 500 Daily rainfall (mm) 0 Average temperature ( o C) Volumetric soil water (%) /13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 8/14 9/14 10/14 10/13 11/13 12/13 1/14 2/14 3/14 4/14 5/14 6/14 7/14 8/14 9/14 10/14 Date

and expected yield Soil N levels determined by previous sorghum (low N) or

6 Northern NSW Year 3 Optimise N and delay nitrate availability. Tamworth (main site: auto chambers) Optimise the N fertiliser rate for soil N and expected yield Soil N levels determined by previous sorghum (low N) or soybean brown manure (high N) +N vs nil N treatments Split N treatment (33% sowing + 67% booting)

7 Year 3 ~ Road-testing options Grain yields Cumulative N 2 O emissions 600 Cumulative N 2 O emissions (g N 2 O-N/ha) sowing (+N) harvest (sorg) + 0 kg N/ha (sorg) kg N/ha (soy) + 0 kg N/ha (soy) + 40 kg N/ha Daily rainfall (mm) Average temperature ( o C) Volumetric soil water (%) /14 11/14 12/14 1/15 2/15 3/15 4/15 5/15 6/15 7/15 8/15 9/15 10/15 10/14 11/14 12/14 1/15 2/15 3/15 4/15 5/15 6/15 7/15 8/15 9/15 10/15 Date Growing season rainfall = 422 mm (longterm = 356 mm)

nitrate in the soil DMPP-coated urea (nitrification inhibitor) [Entec TM ]

8 Northern NSW Year 3 Optimise N and delay nitrate availability. Breeza (satellite site: manual chambers) Delay conversion of urea -> nitrate in the soil DMPP-coated urea (nitrification inhibitor) [Entec TM ] Polymer coated urea (physical isolation of granule) Split N fertiliser (33% sowing + 67% booting)

Year 3 ~ Road-testing options Grain yields Grain yield (t/ha) 8.00 7.00 6.00 5.00 4.00 3.00 2.00 a d cd d bcd bc d cd ab d d cd d Cumulative N 2 O emissions Emission factor (%) 1.00 0.

9 Year 3 ~ Road-testing options Grain yields Grain yield (t/ha) a d cd d bcd bc d cd ab d d cd d Cumulative N 2 O emissions Emission factor (%) Treatment number d c b ab ab a a a a a a a Cumulative N 2 O emissions (g N 2 O-N/ha) Daily rainfall (mm) Average temperature ( o C) Volumetric soil water (%) N (sowing) N (booting) harvest 10/14 11/14 12/14 1/15 2/15 3/15 4/15 5/15 6/15 7/15 8/15 9/15 10/15 10/14 11/14 12/14 1/15 2/15 3/15 4/15 5/15 6/15 7/15 8/15 9/15 10/15 Date 0 kg N/ha at sowing 1:3100% poly :urea urea at sowing at sowing 100% entec urea at sowing 100% poly urea at sowing 100% urea at sowing 33% urea / 67% entec at sowing 33% urea / 67% poly at sowing 33% urea / 33% entec / 33% poly at sowing 100% poly urea at sowing 33% urea at sowing, 67% urea at booting 33% entec at sowing, 67% urea at booting 33% poly at sowing, 67% urea at booting 33% urea at sowing, 67% NV urea at booting 33% entec at sowing, 67% NV urea at booting 33% poly at sowing, 67% NV urea at booting Nil N Growing season rainfall = 253 mm (longterm = 321 mm)

10 Year Reduction in growing-season N 2 O emissions compared to urea applied at sowing Chambers Entec TM applied at sowing Urea applied at booting manual 100% manual 91-97% 80% auto 65-81% 81% manual 81% 58-65%

Delay soil nitrate availability ~ delay conversion of urea to nitrate in the soil DMPP-coated urea (nitrification inhibitor) [Entec TM ]

11 N 2 O mitigation strategies ~ dryland sorghum Optimise the amount of fertiliser N applied for expected yield Delay soil nitrate availability ~ delay N fertiliser application post-sowing or split (sowing + booting) N applied up to the 7 leaf stage can benefit yield Delay soil nitrate availability ~ delay conversion of urea to nitrate in the soil DMPP-coated urea (nitrification inhibitor) [Entec TM ] reduces N 2 O, but also gross margin (no yield benefit) Polymer coated urea (physical isolation of granule) may reduce or increase N 2 O, and also costs more.

12 Southern NSW ~ Rotation trial conclusions Guangdi Li Wagga Wagga Agricultural Institute

13 Treatments 4-year crop sequence Wheat-Canola-Legumes-Wheat Tillage Till vs No-till Nitrogen rate 0, 25, 50 and 100 kg N/ha Nitrogen type Urea, Green Urea, ENTEC

14 N2O emission and emission factors Wheat in 2012 Manual chambers (219 days from 7/8/2012 to 14/3/2013) Treatment N rate N2O-N emission (g/ha) Significance Emission factor (%) (kg N/ha) No-till Till No-till Till Urea Tillage, NS N rate, P< Entec N type, P < Green Urea Canola in 2013 Manual chambers (334 days from 23/5/2013 to 22/4/2014) N rate No-till Till Significance No-till Till Entec Tillage, NS N rate, NS Canola in 2013 Auto-chambers (366 days from 23/5/2013 to 22/4/2014) N rate No-till Till Significance Emission factor (%) Urea Tillage, NS No-till Till N rate, P =

15 Emission under legumes Legumes in 2014 Auto-chambers (386 days from 22/4/14 to 13/5/15) Treatment No-till Till Significance Emission reduction Pea (Brown manured) Tillage, P = % Pasture (Brown manured) Crop type, NS 31.5% Legumes in 2014 Manual chambers (279 days from 28/5/14 to 3/3/15) Crop type No-till Till Significance Emission reduction Lupin (Grain harvested) % Pea (Grain harvested) Tillage, P = % Vetch (Hay cut) Crop type, NS 21.5% Pasture (Hay cut) % Mean % Pasture in Manual chambers 658 days from 14/5/2013 to 3/3/15) Treatment Lucerne mono-culture (L) N2O-N emission (g/ha) 517 Emission reduction Subclover mono-culture (S) % (L vs S) Phalaris-lucerne mix (PL) Phalaris-subclover mix (PS) % (PL vs PS) Significance P = % (L vs PL) -3.0% (S vs PS)

16 N 2 O mitigation strategies ~ southern NSW No-till practice can potentially reduce N2O emissions Including perennial grasses in a pasture mix can capture more nitrate, hence reducing the risk of N2O emission during off-season rainfall events DMPP coated N fertiliser (Entec) can reduce N2O emission, but its high price prevents adoption

17 Simulations of current and future N 2 O emissions and WNMM Model development De Li Liu Wagga Wagga Agricultural Institute

18 MODELLING Model comparison: APSIM, DNDC & WNMM & Model selection: WNMM & DNDC Model improvement/development Simulation of Tamworth previous rotation experimental data Simulation of Tamworth and Wagga experiments conducted in the project Simulation N 2 O under future climate scenarios Model Improvement

19 Model comparison: APSIM, DNDC & WNMM Model selection: WNMM & DNDC Chickpea -wheat-barley Canola+N_wheat+N_barley+N

Model Improvement WNMM: Good performance Input files ~ 100-200 Calibration in the model codes by Yong Li only, no report on actual values used Single-user-model Improve WNMM: WNMM NSWDPI

20 Model Improvement WNMM: Good performance Input files ~ Calibration in the model codes by Yong Li only, no report on actual values used Single-user-model Improve WNMM: WNMM NSWDPI version user friendly interface graphical user interface (GUI) Integrating all necessary inputs into one file, ie. Site & soil file management file model initial file Model parameters/rates etc

21 The first WNMM simulation by a model user - a visiting scientist from Chinese Academy of Science Anyone (non-modeller) can use this WNMM NSW DPI version

22 Simulation of Wagga experiment (WNMM GUI output)

23 Simulation of N 2 O emissions under future climate scenarios IPCC AR5 CSIRO 3.6 RCP2.6, RCP4.5, RCP 6.0 & RCP 8.5 Under four rotation system (Tamworth) CaWB, CpWB, CpWCp & CpS (Ca = canola, W = wheat, B = barley, Cp = chickpea, S = sorghum) by WNMM & DNDC

24 Impact of climate change on N 2 O emission RCP2.6 & 4.5 N 2 O emissions: less than current RCP6.0 & 8.5 N 2 O emissions vary, depending on rotation RCP6.0 & 8.5 CaWB, N 2 O emission will increase by 6 19% Replace canola with chickpea (CpWB), increases N 2 O by only 4 15% Replace barley with chickpea (CpWCp), increase N 2 O by only 3% Rotations including a legume can reduce N 2 O emissions under future changing climate.

25 N 2 O mitigation strategies ~ modelling Under both current and future climate Less fertilizer-dependent cropping More legume cropping phase, less N 2 O emissions WNMM model can predict emissions of various scenarios

THE NATIONAL AGRICULTURAL NITROUS OXIDE RESEARCH PROGRAM (NANORP)

NOT TO BE CITED WITHOUT PERMISSION THE NATIONAL AGRICULTURAL NITROUS OXIDE RESEARCH PROGRAM (NANORP) FINAL SUMMARY (PHASE 1) PETER GRACE CANBERRA 14 JULY 2015 THE NATIONAL AGRICULTURAL NITROGEN USE EFFICIENCY