Contribution of Nitrous Oxide in Life Cycle Greenhouse Gas Emissions of Novel and Conventional Rice Production Technologies

Transcription

1 Contribution of Nitrous Oxide in Life Cycle Greenhouse Gas Emissions of Novel and Conventional Rice Production Technologies Md. Khairul Alam 1 ; Wahidul K. Biswas 2 and Richard W. Bell 1 1 Land Management Group School of Vet. and Life Sciences Murdoch University, WA 2 Sustainable Engineering Curtin University, WA

2 Background

3 Background Wetland rice production and global budget of GHGs

4 GHG from wetland rice GHGs from agriculture counting direct agricultural emissions plus input production and energy use Adapted from Bellarby et al. 2008

5 Fig. Production, consumption and transfer of CH 4 to the atmosphere in rice field (Adapted from Le Mer and Roger, 2001)

6 N2 N2O N2 N2 fixation Photosynthesis OM Bacterial degradation NH4+ Nitrification NO2 NO3 N2O Aerobic condition Denitrification Detrital OM Bacterial degradation NH4+ N2 N2O Anaerobic condition Fig. N 2 O production in soil through microbial transformations

7 Novel technologies to cope with the paucity of labour and water

8 Constraints CH 4 emission N 2 O emission Puddled transplanting Additional fuel consumptions N 2 O emission Direct seeding Mechanical transplanting System of Rice Intensification

9 CH 4 Diffusion through rice arenchyma Diffusion through rice arenchyma C O 2 O 2 O 2 CH 4 CO 2 N2 Litter fall +Mineral N N2O Litter fall + Mineral N N2O CH 4 CO 2 OM NH4+ NO3 Nitrification Aerobic Soil OC (Residual+ Resistant) NO2 NO3 N2O N2O Denitrification Anaerobic OM NH4+ NO3 N2O H 2 +CO 2 CH 4 Ebullition Acetate Diffusion Crop residues /root exudates Resistant OM Organic carbon Resistant OM Production and oxidation in the soil rhizosphere OC+Root=CH 4 CH 4 +O 2 =CO 2 Fig. Trade off between CH 4 and N 2 O under wetland rice conditions

10 A novel solution Non-puddled transplanting of rice

11 Development Non-puddled transplanting of rice/np rice

12 O b j e c t i v e s : To assess the contributions of N 2 O to life cycle GHG emissions for CT and NP with crop residue retention levels To determine the hotspots contributing significantly to the GHG emissions within the system boundaries by a LCA study To identify the causes for the predominant GHG emissions during the pre and on farm stages of rice production. 16-Jan-17

13 Methods

14 Study site: Alipur, Rajshahi M e t h o d s

15 Closed Chamber method M e t h o d s Closed chamber for microbial respiration Chamber - (30 cm length 30 cm width 60 cm height) Chamber base - 31 cm length 31 cm width 7 cm height, Chamber groove - 1 cm 2.5 cm (width deep) Closed gas chambers for CH 4 and N 2 O 60 cm length 30 cm width 100 cm height

16 1 tonne of rice Diesel for transporting seeds Farm machines production, transport Pesticides production packaging & transport Fertilizers production packaging & transport Raw materials extraction from mine CO 2 Photosynthesis Diesel for power tiller Diesel for VMP Diesel for irrigation On-farm CO 2 eq emissions Crop residue Transport (Fertilizer, Seeds, Pesticides, Machines) Paddock for pre-farm activities Paddock for on-farm activities Output: CO2, CH4 and N2O C storage (CS) Cradle System Boundary of SLCA Gate

17 SLCA for field paddy production goal and scope definition inventory analysis impact assessment and interpretation.

18 Greenhouse gas emissions calculated for the following practices: Conventional puddled transplanting with low residue retention (CTLR) Conventional puddled transplanting with high residue retention (CTHR) Non-puddle transplanting with low residue retention (NPLR) Non-puddle transplanting with high residue retention (NPHR)

19 Life cycle inventory Pre farm emissions Chemicals Fertiliser Pesticides Herbicides Farm machinery Plough/PT/VMP Harvester Transport Trucks Shipping On farm emissions Farm machinery Soil Ref: Alam et al. 2016; Journal of Cleaner Production 112(5):

20 Impact assessment Global warming potential (GWP) Greenhouse gas Time horizon 20 years 100 years 500 years Carbon dioxide Methane Nitrous oxide Source: IPCC, 2013

21 R e s u l t s

22 Pre-farm emission (kg CO2eq/tonne rice) ns ns CTLR CTHR NPLR NPHR ns 2a. Pre-farm o 7-11% of total LCA emission. o Lower than any other paddy LCA ns in the world. Causes: o Lower level of input used o Use of natural gas as a feed stock o Light vehicles used Rice cultivation practices Legend: CT = Conventional puddled transplanting NP = Non-puddle transplanting HR = High residue retention (NPTHR) LR= Low residue retention (NPTLR)

23 On-farm emission (kg CO2eq/tonne rice) 1600 a 2 b. On-farm 1200 b d c CTLR CTHR NPLR NPHR Rice establishment technique

24 Total emission (kg CO2eq/tonne rice) b a d c Farm machinery use N2O emission from paddock (CO2 eq) CH4 emission from paddock (CO2eq) CO2 emission from paddock Transportations of inputs 0 CTLR CTHR NPTLR NPTHR Emissions by treatments Production of inputs Fig. 2c. Total emissions showing contributions from different sources.

25 CTLR (100 years time horizon) N2O emission from paddock (CO2 eq) 3.5% Farm machinery use 15% Production of inputs 7% CH4 emission from paddock (CO2eq) 62.5% Transportati ons of inputs 3% CO2 emission from paddock 9%

26 N2O emission from paddock (CO2eq) 3% CTHR (100 years time horizon) Farm machinery use 13% Production of inputs 6% CH4 emission from paddock (CO2eq) 67% Transportatio n of inputs 2% CO2 emission from paddock 10%

27 NPLR (100 years time horizon) N2O emission from paddock (CO2 eq) 2% CH4 emission from paddock (CO2eq) 60% Farm machinery use Production 16% of inputs 9% Transporta tions of inputs 3% CO2 emission from paddock 10%

28 N2O emission from paddock (CO2 eq) 2% CH4 emission from paddock (CO2eq) 64% NPHR (100 years time horizon) Farm machinery use 15% Production of inputs 7% Transportati ons of inputs 3% CO2 emission from paddock 9%

29 CH4 (CO2-eq) emission 1200 a CH4 (CO2-eq) 900 b d c CTLR CTHR NPLR NPHR Different practices

30 N2O (CO2-eq) emission N2O (CO2-eq) a a b b CTLR CTHR NPLR NPHR Different treatments

31 CO2 emission 200 CTLR CTHR NPLR NPHR CO2 (CO2-eq) 160 a 120 b bc c CTLR CTHR NPLR NPHR Different practices

32 Conclusions

33 Conclusions The CTHR emitted about 1.4 times more GHG emissions for one tonne rice than NPLR. Applying NPLR in the wetland rice system of the EGP can reduce GHG emissions to 1.1 tonne CO 2 eq tonne 1 rice production. The on farm stage contributed the highest portion of the total GHG emissions. CH 4 was the predominant GHG from 1 tonne of rice production. N 2 O emission contributing only % of the total LCA GHG. We recommend additional SLCA studies for all the crops of the cropping system. Ref: Alam et al. 2016; Journal of Cleaner Production 112(5):

34 Acknowledgements Bangladesh Agricultural Research Institute Bangladesh Council for Scientific and Industrial Research Farmer at Alipur, Bangladesh who permitted the use of their lands. Australian Centre for International Agricultural Research (Project LWR 2010/080 and a John Allwright Fellowship to the senior author) for their funding support.

35 Your patience appreciated