1. Ammonia emission from standing crops and crop residues TFEIP Agriculture and Nature expert panel meeting Ghent, 2014 Jan Vonk MSc (RIVM) The Netherlands Ammonia emission from standing crops and crop residues | May 13th, 2014

2. Contents 1.Introduction 2.Ammonia emissions from: a) standing crops b) crop residues c) grassland 3.Estimated emissions in the Netherlands 4.Discussion/conclusions Ammonia emission from standing crops and crop residues | May 13th, 2014

3. Acknowledgement ●Contents based on the research of De Ruijter et al., 2013 –Conducted by: ›Plant Research International of Wageningen UR (PRI-WUR) ›National Institute for Public Health and Environment (RIVM) –Funded by: ›Ministry of Infrastructure and Environment (IeM) ●Presentation co-authors –J.F.M. Huijsmans (PRI-WUR) –F.J. de Ruijter (PRI-WUR) –W.A.J. van Pul (RIVM) Ammonia emission from standing crops and crop residues | May 13th, 2014 3

4. Introduction ●EMEP 2009 Guidelines –Standing crops/crop residues recognized as NH 3 emission sources –However extremely uncertain: ›Type of crop ›Environmental conditions ›Success of harvest ›Fertilizer amount ›Seasonal/diurnal variations ›Ambient NH 3 concentration –As a result no default method is given Ammonia emission from standing crops and crop residues | May 13th, 2014 4

5. Ammonia emission from standing crops (1) ●Resistance model, DEPAC (Van Zanten et al., 2010) –Atmospheric transport –Layer above canopy –Canopy surface ›External ›Vertical transport ›Stomatal/mesophyll Ammonia emission from standing crops and crop residues | May 13th, 2014 5

6. Ammonia emission from standing crops (2) Ammonia emission from standing crops and crop residues | May 13th, 2014 6

7. Ammonia emission from standing crops (3) ● Γ s values obtained from extensive literature review *no experimental data, conservative defaults used Ammonia emission from standing crops and crop residues | May 13th, 2014 7 CropArea NL (* 1,000 ha) Γ lower Γ medium Γ upper Grassland intensive 5235002,0004,000 Maize2622001,5004,000 Potatoes*1545001,0002,000 Cereal crops1915002,0004,000 Sugar beet*765001,0002,000

8. Ammonia emission from crop residues (1) ●Regression model (De Ruijter and Huijsmans, 2012) –Relationship of ammonia emission and N content of residues ›NH 3 -N volatilization (%) = 0.40 * N content – 5.08 (R 2 = 0.50) ●No emission if N content is below 12.7 g/kg ●Assumes complete exposure to air, both in the amounts of residue and in time ●Current study: –Amount of crop residues and N content derived from literature –Expert opinions on degree of incorporation Ammonia emission from standing crops and crop residues | May 13th, 2014 8

9. Ammonia emission from crop residues (2) ●Averages (and range) per crop of: –Residue dry matter –N in crop residue –Contributing fraction ●Including green manure crops, when killed by frost or herbicides Ammonia emission from standing crops and crop residues | May 13th, 2014 9

10. Ammonia emission from grassland ●Already included in the inventory: –Emissions after application of manure and fertilizer –Emissions during grazing ●Not yet included: –Emissions from non-grazed grassland between applications of manure and fertilizer ›Standing crops –Emissions from crop residues ›Pasture topping ›Losses during silage/hay production ›Grassland renovation Ammonia emission from standing crops and crop residues | May 13th, 2014 10

11. Estimated emissions in the Netherlands ●Standing crops –Hourly emission fluxes based on weather data (Royal Netherlands Meteorological Institute, KNMI) and ambient air ammonia concentrations (National Air Quality Network of RIVM) –Integral over growing season of the crop ›Always emission if ambient ammonia concentration is below 5 µg/m 3, between 5-12 µg/m 3 depending on Γ s value, emission stops above 12 µg/m 3 ›Emission between 0 and 6 Gg NH 3 -N, best estimate: 1.5 Gg ●Crop residues –Emission between 0.3 and 3.8 Gg NH 3 -N, best estimate: 1.9 Gg Ammonia emission from standing crops and crop residues | May 13th, 2014 11

12. Discussion/conclusions (1) ●Large uncertainty in emission of standing crops ●Two parameters dominate the estimate: –Ambient ammonia concentration (uncertainty < 10%) –Stomatal compensation point › Γ s values can range up to a factor of ten ●Focus should be on improving the Γ s values being used –Differences in agricultural management (N fertilization) –Climate effects (temperature) ●Abatement techniques, for instance on animal housing, could partly be countered by higher emissions from standing crops Ammonia emission from standing crops and crop residues | May 13th, 2014 12

13. Discussion/conclusions (2) ●Ammonia emission from crop residues starts after a few days and peaks between 1 to 4 weeks –Because emission is more pronounced, less effect of ambient ammonia concentration –Emission can be prevented by incorporation into the soil as much/soon as possible ›Notable exceptions: potatoes, grassland ●Decreases in fertilization leads to lower N contents of crop residues and volatilization rates (non-linear) –Developments in N contents need further study Ammonia emission from standing crops and crop residues | May 13th, 2014 13

14. Literature ●Ruijter, F.J. de, J.F.M. Huijsmans, M.C. van Zanten, W.A.H. Asman & W.A.J. van Pul (2013). Ammonia emission from standing crops and crop residues. Contribution to total ammonia emission in the Netherlands. Plant Research International report 535, Wageningen, the Netherlands. ●Zanten, M.C. van, F.J. Sauter, R.J. Wichink Kruit, J.A. van Jaarsveld & W.A.J. van Pul (2010). Description of the DEPAC module. Dry deposition modelling with DEPAC_GCN2010. RIVM report 680180001, Bilthoven, the Netherlands. ●Ruijter, F.J. de & J.F.M. Huijsmans (2012). Ammonia emission from crop residues. Quantification of ammonia volatilization based on crop residue properties. Plant Research International report 470, Wageningen, the Netherlands. Ammonia emission from standing crops and crop residues | May 13th, 2014 14

15. One sentence summary Ammonia emissions from standing crops and crop residues are likely to be considerable, but depend on several factors (crop type, N fertilization, climate and ambient ammonia concentration) and therefore the variation and uncertainty will be large. Wanted: Γ s values, got any? Please let us know at jan.vonk@rivm.nl Ammonia emission from standing crops and crop residues | May 13th, 2014 15