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 Alam1; Wahidul K. Biswas2 and Richard W. Bell1 1Land Management Group School of Vet. and Life Sciences Murdoch University, WA 2Sustainable 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 CH4 to the atmosphere in rice field (Adapted from Le Mer and Roger, 2001)

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

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

8 Constraints CH4 emission Puddled transplanting Additional fuel consumptions Mechanical transplanting N2O emission Direct seeding N2O emission System of Rice Intensification

9 C O2 O2 CH4 Diffusion through rice arenchyma Diffusion through rice arenchyma O2 CH4 CO2 N2 Litter fall +Mineral N N2O Litter fall + N2O Mineral N OM Nitrification NH4+ NO3 Aerobic Soil OC (Residual+ Resistant) CH4 OM N2O NO2 NO3 Ebullition N2O NH4+ NO3 Denitrification Anaerobic CO2 Diffusion CH4 Crop residues /root exudates H2+CO2 Acetate N2O Organic carbon Resistant OM Resistant OM Production and oxidation in the soil rhizosphere OC+Root=CH4 CH4+O2=CO2 Fig. Trade off between CH4 and N2O under wetland rice conditions

10 A novel solution Non-puddled transplanting of rice

11 Development Non-puddled transplanting of rice/np rice

12 Objectives: To assess the contributions of N2O 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. 21-Dec-16

13 Methods

14 Methods Study site: Alipur, Rajshahi

15 Methods Closed Chamber method 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 CH4 and N2O 60 cm length 30 cm width 100 cm height

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

17 SLCA for field paddy production Life cycle inventory Impact assessment Pre farm emissions On farm emissions Global warming potential (GWP) Greenhouse gas emissions calculated formachinery the goal and scope definition Farm Chemicals following Greenhouse practices: Time horizon Soil inventory analysis Fertiliser gas 20 years 100 years 500 years Pesticides impact assessment and Conventional puddled transplanting with low residue Herbicides Carbon retention (CTLR) interpretation. dioxide residue Farm machinery Conventional puddled transplanting with high Plough/PT/VMP Methane retention (CTHR)72 Harvester Nitrous Non-puddle transplanting with low residue retention (NPLR) oxide Transport Non-puddle transplanting with high residue retention Source: IPCC, 2013 (NPHR) Trucks Shipping Ref: Alam et al. 2016; Journal of Cleaner Production 112(5):

18 Results

19 2a. Pre-farm Pre-farm emission (kg CO2eq/tonne rice) ns 120 ns ns ns o 7-11% of total LCA emission. o Lower than any other paddy LCA in the world. Causes: o Lower level of input used o Use of natural gas as a feed stock o Light vehicles used CTLR CTHR NPLR NPHR Rice cultivation practices Legend: CT = Conventional puddled transplanting NP = Non-puddle transplanting HR = High residue retention (NPTHR) LR= Low residue retention (NPTLR)

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

21 Total emission (kg CO2eq/tonne rice) a Farm machinery use b d 1200 c N2O emission from paddock (CO2 eq) CH4 emission from paddock (CO2eq) CO2 emission from paddock Transportations of inputs Production of inputs CTLR CTHR NPTLR NPTHR Emissions by treatments Fig. 2c. Total emissions showing contributions from different sources.

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

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

24 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%

25 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%

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

27 N2O (CO2-eq) 45 N2O (CO2-eq) emission a a b b NPLR NPHR CTLR CTHR Different treatments

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

29 Conclusions

30 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 CO2 eq tonne 1 rice production. The on farm stage contributed the highest portion of the total GHG emissions. CH4 was the predominant GHG from 1 tonne of rice production. N2O 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):

31 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.

32 Your patience appreciated