Feedback and Global Changes in N 2 O and CH 4 emissions from natural and managed land

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1 Feedback and Global Changes in N 2 O and CH 4 emissions from natural and managed land Klaus Butterbach-Bahl Institute of Meteorology and Climate Research, Karlsruhe Institute of Technology, Garmisch-Partenkirchen, Germany

2 Why to look at soils when talking about atmospheric C and N-trace gases and global change? Fossil fuel burning CO 2 Land use change Industrial sources Rice paddies, wetlands, ruminants CH 4 Industrial sources N 2 O Agriculture, forests, ozeans Soils: 6-7% Forster et al., 27, In: Climate Change 27

3 Global Changes and soil N 2 O and CH 4 exchange Land use Climate change Atmosph. Compos. Change Manag. Temp. Precip. CO 2 N-Dep. (O 3, ) Physico-chemical environment (radiat., soil T& - moist., compact., O 2, C/N avail.) Soil C and N turnover Soil microbial community Plant litter (QA/QN) & Exudation Plant species composition Plant Physiology (WUE, Photosynthesis) Nitrification Denitrification CH 4 -Prod. CH 4 -Oxid. Biospere-Atmosphere Exchange of CH 4 & N 2 O

4 CH 4 -exchange is the result of simultaneous microbial production and consumption processes CH 4 -flux = CH 4 -Production CH 4 -Oxidation Methanogenic bacteria Methanotrophic bacteria Dunfield, 27, Cabi.org

5 +5 N 2 O-exchange is the result of simultaneous microbial production and consumption processes NO NO 2 +3 NO NO +1 N 2 O ± N 2 Wrage et al. 21, Soil Biol. Biochem. -1 NH 2 OH -2-3 NH 3 NH + 4 Nitrification Denitrification DNRA, ANAMMOX Abiological

6 Tilled versus no-tilled systems Land use Change Manag. Climate change Temp. Precip. Atmosph. Compos. CO 2 N-Dep. (O 3, ) SOC SOC ( cult.) SOC ( no-till) Time [yr]

7 Tilled versus no-tilled systems No-till - tilled [kg N 2 O-N ha -1 yr -1 ] humid climate dry climate Years Six et al., 24, Global Change Biol.

8 Understanding the coupling between C and N cycling +soil microbial activity Increased SOC -O 2 avail. +soil N- cycling +DOC avail. simulated annual N2O flux (kg N/ha/yr) SOC (kg C/kg soil) Increased N 2 O observed annual N2O flux (kg N/ha/yr) Li et al., 25, Climatic Change

9 Feedback of SOC increase on total GHG balance N 2 O or CH 4 exchange [kg N or kg C ha -1 yr -1 ] C-sequestration [kg C ha -1 yr -1 ] standard alternative Iowa Hebei Bavaria Li et al., 25, Climatic Change Iowa Hebei Bavaria Maize/wheat -residue -> +residue Maize/soybean till -> no-till Barley -manure -> +manure

10 Feedback of SOC increase on total GHG balance Change in net-ghg emissions, alternative - standard (kg CO 2 -equivalents ha -1 yr -1 ) Iowa Hebei Bavaria CH 4 N 2 O C-sequestration in soil Total Li et al., 25, Climatic Change

11 Grazed versus non-grazed steppe systems Land use Change Manag. Climate change Temp. Precip. Atmosph. Compos. CO 2 N-Dep. (O 3, )

12 Grazed versus non-grazed steppe systems: N 2 O Soil T & moisture N 2 O-flux Soil N 2 O-concentr

13 Grazed versus non-grazed steppe systems: N 2 O Extremely high N 2 O-fluxes during freeze-thaw from ungrazed steppe >7% of annual fluxes 27 28

14 Do natural steppe systems emit more N 2 O than grazed systems? NO On a regional scale nutrient management overrides site scale effects Upland steppe Riparian area Urine patches Sheepfold Dung heap Stocking rate [sheep ha -1 ] N2 O-flux [g N ha-1 vegetation period] Daily air temperature ( C) Jul Aug Sep Oct Mar Mar Apr May Jun N2 O flux (N 2 O-N mg m-2 h -1 ) Sep Aug Jul Jun May Holst et al., 27, Plant and Soil

15 Grazed versus non-grazed steppe systems: CH 4 UG WG Texture sl sl ph 6.8±.3 6.7±.3 SOC [%] 2.5±.6 2.6±.5 Bulk dens. [g cm -3 ] Gas Perm. -3kPa [cm d-1] 1.9±.1 1.9± ± ±38

16 Do natural steppe systems take up more CH 4 than grazed systems? CH 4 flux (µg CH 4 -C m -2 h -1 ) H1 H2 H3 H4 H5 H6 H7 H µg CH 4 -C m -2 h -1 2 kg C ha -1 growing season x.98 = kg C ha -1 CH 4 uptake (µg CH 4 -C m -2 h NO CH 4 emission from riparian areas and from sheep are more important as CH 4 uptake by steppe soils X1 X2 X3 X4 X5 X6 X7 X8 1.1 mg CH 4 -C m -2 h -1 7 kg C ha -1 growing season X.2 = 1.4 kg C ha -1 Sheep CH 4 emissions g CH 4 -C sheep day kg C ha -1 growing season X2 = 2.2 kg C ha -1

17 Nitrogen cycling changes during the past two centuries Land use Change Manag NO y N NH x Climate change Atmosph. Compos. Temp. Precip. CO 2 N-Dep. (O 3, ) mid-199s 2 1 NO 25 y N N 2 + 3H 2 2NH NH x Galloway et al., 23,Biogeochemistry

18 Nitrogen depostion past and present Holland et al., 1999, Biogeochemistry, EMEP, 22

19 Nitrogen oxide emissions from Forests in Europe (NOFRETETE) 25 NO-Emission [µg NO-N m -2 h -1 ] Mean: µg N m -2 h -1 N 2 O-Emission [µg N 2 O-N m -2 h -1 ] 1 5 Mean: µg N m -2 h

20 Nitrogen oxide emissions from Forests in Europe (NOFRETETE) Stimulation of N-oxide emissions from soils at sites with high N- deposition and narrow C/N ratios Pilegaard et al., 26, Biogeosciences

21 Nitrogen oxide emissions from Forests in Europe (NOFRETETE) Cultivated Area Forest Area N 2 O Emission (kg N 2 O-N ha -1 a -1 ) % of agricultural soils 2 Kesik et al., 25, Biogeosciences

22 Forest management, N deposition and N 2 O fluxes (Höglwald) Land use Change Manag. Climate change Temp. Precip. Spruce control Selective cutting 2/26 Höglwald Clear cut 2 Atmosph. Compos. CO 2 N-Dep. (O 3, )

23 Clear-cutting enhances N 2 O emissions for years N 2 O emission [µg N m -2 h -1 ] Cutting Annual N 2 O emission [kg N ha -1 yr -1 ] Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan

24 Clear-cutting reduces CH 4 uptake for decades 45 CH 4 flux [µg CH 4 -C m -2 h -1 ] Annual CH 4 fluxes [kg C ha -1 yr -1 ], -,5-1, -1, Years 2-27 N 2 O CH 4 N 2 O+CH 4-3 Kg N ha -1 Kg CO 2eq ha -1 Kg C ha -1 Kg CO 2eq ha -1 Kg CO 2eq ha -1 Control Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Jul Jan Selected cutting Clear-cut

25 Combined N-/ CO 2 -effects on CH 4 -exchange in rice paddies Land use Change Manag. Climate change Temp. Precip. Atmosph. Compos. CO 2 N-Dep. (O 3, ) b

26 Combined N-/ CO 2 -effects on CH 4 -exchange in rice paddies (a) 21, N25-HR 6 Elevated 4 Ambient (b) 22, N25-MR (c) 23, N25-MR Methane emission flux (mg CH4 m -2 h -1 ) 2 (d) 21, N15-HR (g) 23, N15-HR 6 4 (e) 22, N15-MR (h) 23, N15-ZR (f) 23, N15-MR Days after rice transplanting (d) Zheng et al., 24, Global Change Biol.

27 Combined N-/ CO 2 -effects on CH 4 -exchange in rice paddies Change in seasonal accumulative methane emission (%) N15 N25 N Application rate of crop residues (kg C ha -1 ) CO 2 effect diminish with increasing rates of residue application Zheng et al., 24, Global Change Biol.

28 Combined N-/ CO 2 -effects on CH 4 -exchange in rice paddies 27 Change in seasonal accumulative methane emission (%) Annual nitrogen application rate (kg N ha -1 ) CO 2 effect is further stimulated by additions of nitrogen fertilizer Zheng et al., 24, Global Change Biol.

29 Combined N-/ CO 2 -effects on CH 4 -exchange in rice paddies Elevated CO 2 + CH 4 emission + + Added nitrogen Aerenchyma Plant growth + + Residues Root exudation Microbial activity CH 4 production Decomposition Soil nitrogen availability + Zheng et al., 24, Global Change Biol. N/C CH 4 oxidation Schimel, 2, Nature

30 Climate change and the variability of fluxes - Höglwald Land use Change Manag. Climate change Temp. Precip. Atmosph. Compos. CO 2 N-Dep. (O 3, ) Continuous measurements of N 2 O emissions and 1999-present N deposition 2-3 kg N Loamy soil texture

31 Climate change and the variability of fluxes - Höglwald Temperature [ C] N 2 O-emission [g N 2 O-N ha -1 d -1 ] NO-emission [g NO-N ha -1 d -1 ] A B C Precipitation [mm] Jan Apr Jul Oct Jan Apr Jul Oct Jan Apr Jul Oct Papen & Butterbach-Bahl, J Geophys. Res, 1999; Butterbach-Bahl et al.,j. Geophys. Res. 21

32 Climate change and the variability of fluxes - Höglwald 3.5 Annual N 2 O flux [kg N ha -1 yr -1 ] non-freeze/thaw fluxes freeze/thaw fluxes n.d n.d.

33 TERENO Alpine Observatory for studying Global Change Impacts Land use Change Manag. Climate change Temp. Precip. Atmosph. Compos. CO 2 N-Dep. (O 3, )

34 TERENO Climate Feedback Station Ammer Catchment

35 TERENO Climate Feedback Station Ammer Catchment

36 Towards full N balance studies Höglwald, spruce forest (Germany) Plant N turnover 9 15 NH 3 /NO 2 1 N-Deposition 4 NH 3 /NH 4 NO 2 /NO 3 DON Volatilisation 1 N 2 O ~ 1 NO ~ Microbial N turnover 5 Leaching

37 Summary and questions no simple solutions 1) New technologies? Closed nutrient cycles, especially with regard to N and P (not new!) Use of residues for bioenergy production (not new!) Huge reduction potentials at hotspots (approx. 5-9%) 2) Energy source? Bioenergy production. Adverse effects (N 2 O/biodiv/food production) 3) Research opportunities? Landscape/ regional analysis of nutrient cycling and associated non- CO 2 and CO 2 GHG exchange at identified hotspots (e.g. China) 4) Process understanding to allow manipulation? Holistic view of GHG exchange long-term measurements 5) Reductions and efficient energy use? Integrated landscape management, optimization of land use and management integrated measuring and modeling studies

38 Thank you

39 Forest management, N deposition and N 2 O fluxes (Höglwald) Ammonium NH 4 Control Selective cutting Clearcut Nitrate NO kg N ha -1 yr kg N ha -1 yr Treatment Average Control Selected cutting Clear-cut Huber et al., 24, Plant and Soil

40 Human drivers Land use change + Fossil fuel burning + + Industrial N 2 fixation Biogeochemical Cycles Atmospheric drivers Atmospheric CO 2? + Primary production Carbon Cycle Gruber & Galloway, Nature 28 +? + Climate warming???? C/N ratio + N 2 fixation + Denitrification Atmospheric reactive N? N-Cycle + + Biologically Available N +? +

41 Forest management, N deposition and N 2 O fluxes (Höglwald) Spruce control Selective cutting Clearcut Control site without treatment (last thinning 1975) Area of 1 ha with selective cutting in 2 and 26 (removal of c. 2 % of the trees each time) Area of 1 ha, clearcut in 2 and planted with beech Start of the experiment: July 1999 (pre-treatment phase) Cutting: End of February 2, 26