1. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 1 Methodology for calculating N 2 O emissions from agricultural soils in Sweden – remarks on national emission factors Håkan Staaf Swedish Environmental Protection Agency Natural Resources Department SE -106 48 Stockholm, Sweden prepared for the Expert meeting on improving the quality of greenhouse gas emission inventories for category 4 D, 21-22 October 2004, Ispra, Italy

2. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 2 N 2 0 emissions from agricultural soils - Sweden 2002

3. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 3 Nitrous oxide emissions from agricultural soils – Emission factors used by Sweden (2003 submission) Emission factorSource Direct soil emissions Mineral fertiliser0,8 %National Manure2,5 %National Crop residues; N fixing crops1,25 %IPCC Cultivation of histosols8 kg N 2 O-N/ha yrIPCC Animal production Animal excretion - arable land2 %IPCC Animal excretion - pasture1 %National Indirect emissions from soil Atmospheric deposition1%IPCC N leaching and runoff2,5 %IPCC Other Cultivation of mineral soils0,5 kg N 2 O-N/ha yrNational

4. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 4 Emission factors for N 2 O emission from cultivation of soils Emission factors for emission from cultivation of agricultural soils CropEF (kg N 2 O-N/ha) Exp.data NIR Mineral soils All crops0,5 Organic soils Annual crops68 Perennial crops (grass/pasture) 1 For organic soils ; - experimental data suggests different emission factors for annual and perennial crops - IPCC standard value still used For mineral soils ; - half the background value according o Bowman (1996) considered to be caused by cultivation

5. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 5 Sources of N 2 O background emission in soil? A. 1) N - mineralisation of SOM 2) Mineralisation of dead roots 3) Crop residues ------------------------------------------------------- N-mineralisation of SOM in Swedish cultivated mineral soils Mean N content of soil (0-25 cm) = 0,30 % (Eriksson et al 1997) 2,4 M ha x 10 ton N/ha = 24 Mton organic N Assumptions: a) Mineralised fraction = 1 % / yr (Steinek et al 2000); b) fraction of mineralised N emitted as N 2 O-N = 1,25 % Estimated total N 2 0 emission from arable soil = 3,8 kton/yr

6. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 6 Sources of N 2 O background emission in soil? B. This rough estimate indicates: -Emission from crop residues probably lower than background -Decomposition of roots may be included in mineralisation of SOM -The emission from cultivation of mineral soils reported by Sweden is almost identical to 50% of the estimated emission caused by net mineralisation of N from SOM Emissions yr 2002Kton N2O Cultivation of min. soils1,92 Crop residues1,27 Decomposition of roots ? Mineralisation of SOM3,8 Miner. of SOM x 0,51,9

7. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 7 Emission factor for mineral fertilizer – experimental data from mineral soils National emission factor 0,8 % Experimental data for organic fertilizers applied to grassland. NW Europe N=55. (Data from: Ambus & Christensen 1995, Allen et al. 1996, Christensen 1983, Clayton et al. 1997, Dobbie et al. 1999, Duyzer 1996, Flessa et al. 1998, Heinemeyer et al. 1996, Jörgensen et al. 1997, Kaiser et al. 1998, Mogge et al. 1999, Poggeman et al. 1997, Schmädeke et al. 1997, Smith et al. 1998, Velthof et al. 1996, Vermoesen et al. 1996)

8. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 8 Emission factor for manure applied to mineral soils – Experimental data National emission factor, 2,5 %, based on experimental data on organic fertilizers to grain crops and grasslands, until yr 1999 N. Europa and Canada. N=16. (Data from: Ambus m.fl. subm. Chang et al. 1998. Clayton et al. 1997. Heinemeyer et al. 1996. Kasimir-Klemedtsson et al. In prep. Mogge et al. 1999. Poggemann et al. 1999.

9. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 9 N 2 O from grazing animals In Sweden; about 500 000 ha of extensively used, non-fertilized pastures Most available emission data pertain to intensely managed grassland Data from unfertilized grassland in N. Zealand indicate en emission factor of 0,2 – 1% (see Revised 1996 IPPC Guidelines) We use the following EFs; 1 % for extensively used grassland (pasture) and 2 % for intensively used grassland (ley) The weighted EF is about 1,8 %

10. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 10 Comparison of N 2 O emissions from agricultural soils calculated for 1990 – 2002 using national and IPCC standard EFs

11. NATURVÅRDSVERKET/SWEDISH ENVIRONMENTAL PROTECTION AGENCY Ispra, 21-22 October 2004 11 Summary - some remarks on the present methodology for calculating N 2 O emissions from agricultural soils EFs do not include long-term effects of manure application More relevant for mineral fertilizers to crops (no N accumulation) Mitigation effects (reduced fertilization) are overestimated Includes both net N additions and internal circulation Risk for double-counting Biologically sound to include elevated background emissions in surveys but may lead to double-counting (background, crop residues, manure) The emission from cultivation of mineral soil as reported by Sweden may be explained by mineralisation of SOM For Sweden, use of national EF gives higher N2O emission from soil than default; the temporal trend is unaffected