Session 40-2. Author: Lisbeth.Mogensen@agrsci.dk Life cycle assessment of organic milk production in Denmark Lisbeth Mogensen, Marie T. Knudsen, John E. Hermansen, Troels Kristensen, Thu Lan T. Nguyen U N I V E R S I T Y O F A A R H U S Faculty of Agricultural Sciences
Outline of the presentation Introduction Aim of the study Materials An organic dairy farm in Denmark Methods Life cycle assessment (LCA) Results Improvement options Conclusion
Aim of this study Estimate the GreenHouse Gas (GHG) emission of Danish organic milk through Life-Cycle Assessment (LCA) based on data that typically are available at the farm Suggest possibilities for reduction of the GHG emission on farm gate
Materials Typical annual data from an organic dairy farm: Economic turnover Manure account Production performance
The herd Cows Heifers Bull calves No. 192 297 3) 142 1) Milk yield, kg 9000 Housing Cubicles Deep litter Deep litter Summergrazing 8 h per day 24 hours 2) 0 1) Sold at 60 kg 2) For heifers > 6 months 3) High number due to extended the herd size
The fields 320 ha in rotation on sandy soil 21 ha permanent pasture Ha % Grass clover 128 40 Cereals for whole crop 77 24 Cereals for maturity 104 33 Carrots 10 3
Methods Life cycle assessment (LCA) N 2 O N2 O CO 2 Soy bean from Argentina N 2 O Fertilizer production CO 2 CO 2 CO 2 CH 4 Milk
The system boundaries: INPUT Materials Manure Feed Seed Energy Diesel Electricity Chemicals Other Emissions to the air (CO 2, N 2 O, CH 4, NH 3 ) The farm Emissions to soil and water (NO 3-, PO 4 3- ) OUTPUT Crops Milk and meat Byproducts transport transport transport transport Fertilizer and feed production Farm Processing Supermarket Consumer
Functional unit (FU) 1) GHG emission of the whole farm (kg CO 2 -eq/farm/year) 2) After biological allocation: GHG per 1 kg milk ex farm (kg CO 2 -eq/kg milk)
Inventory: Input and output Emissions to air (CO 2, N 2 O, CH 4, NH 3 ) INPUT Materials 3000 t slurry 302 t barley 80 t soy meal 137 t straw N 2 fixation Seed Energy 29,954 l diesel 6237 l diesel (contractor) 280,023 kwh el Chemicals Other Stable Cattle manure The farm Fields 128 ha grassclover 77 ha whole crop 104 ha cereals 10 ha carrots Emissions to soil and water (NO 3-, PO 4- ) OUTPUT Milk 1,726,751 kg (sold) Meat 69,751kg live weight (sold) Crops 700 t carrots (sold) 233 t DM silage (store) Manure 692 t cattle slurry (sold) 359 t cattle slurry (store)
CO 2 emission from external input Input of CO 2 -eq emission, kg 1 kg barley 0.694 1 kg soy bean meal 0.934 1 kg N plant from manure 9.120 1 litre diesel 3.309 1 kwh electricity 0.655
CH 4 emission estimation CH 4, kg Area Amount Emission Factor Enteric fermentation Kg DMI x 18.45 MJ/kg DM / (55.65 MJ/kg CH 4 ) 0.06 Manure - slurry - deep litter - pasture Non-digestible organic DMI + organic matter used as bedding 0.1 0.01 0.01 CH 4 formation capacity=0.22 (IPCC, 2006)
N 2 O emission estimation N 2 O, kg direct Indirect N 2 O Area Amount Emission Factor Stable & storage N manure ex animal - slurry 0.005 - deep litter 0.01 Application N manure ex storage - manure 0.01 - pasture 0.02 Crop residues Sum ha * kg N per ha per year 0.01 Grassland 50 N Other arable crop 30 N From NH 3 NH 3 -N 0.01 From leacing N0 3 -N=0.33*(N manure ex 0.0075 storage+n import fertilizer) (IPCC, 2006)
Total farm GHG emission Kg CO 2 -eq. Total farm GHG 2,347,600 Per ha 6,880 Per kg milk before allocation 1.36 Per kg milk allocated 1.02 Per kg meat allocated 16.1
GWP hotspots INPUT ENERGY ON FARM EMISSIONS 16% 12% 72% 36% 284 56 141 150 522 1159 Seed Feed Production of fertilizer Diesel El Transport of fertilizer N 2 O from fields CH 4 from animals Kg CO 2 -eq 0 500 1000 1500 2000 Klimabelastning (tons CO 2 ækv./bedrift per year)
Contribution per GHG 17% 50% 33% CO2 N2O CH4
Improvement options Increased N efficiency Reduced N application: 140 to 115 kg N/ha Import of N reduced by 8,000 kg Crop yield at same level
Total farm GHG reduced by 5% IMPORT 14% ENERGY EMISSIONs 13% 73% 284 139 150 458 1159 Basic Seed Feed Diesel El N 2 O at fields CH 4 from herd 0 500 1000 1500 2000 Klimabelastning (tons CO 2 ækv./bedrift per year)
Conclusion Farm GHG can be calculated based on typical farm data Improvement in farm GHG in the present case: 5% of total Farm GWP only one of several impact categories in a LCA (acidification, nutrient enrichment, land use etc.)