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

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

Contents

1. Introduction2. Ammonia emissions from:

a) standing cropsb) crop residuesc) grassland

3. Estimated emissions in the Netherlands

4. Discussion/conclusions


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)


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Introduction● EMEP 2009 Guidelines

– Standing crops/crop residues recognized as NH3 emission sources

– However extremely uncertain:› Type of crop› Environmental conditions› Success of harvest› Fertilizer amount› Seasonal/diurnal variations› Ambient NH3 concentration

– As a result no default method is given


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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


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Ammonia emission from standing crops (2)● Emission calculation

– , with:

› xa atmospheric concentration

› xs stomatal compensation point

– , with:

› Γs ratio between ammonium concentration and pH in the apoplast of the mesophyll


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Ammonia emission from standing crops (3)● Γs values obtained from extensive literature review

*no experimental data, conservative defaults used


Crop Area NL(* 1,000 ha)

Γlower Γmedium Γupper

Grassland intensive

523 500 2,000 4,000

Maize 262 200 1,500 4,000

Potatoes* 154 500 1,000 2,000

Cereal crops 191 500 2,000 4,000

Sugar beet* 76 500 1,000 2,000

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Ammonia emission from crop residues (1)● Regression model (De Ruijter and Huijsmans, 2012)

– Relationship of ammonia emission and N content of residues

› NH3-N volatilization (%) = 0.40 * N content – 5.08 (R2 = 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


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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


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


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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/m3, between 5-12 µg/m3 depending on Γs value, emission stops above 12 µg/m3

› Emission between 0 and 6 Gg NH3-N, best estimate: 1.5 Gg

● Crop residues– Emission between 0.3 and 3.8 Gg NH3-N, best estimate: 1.9 Gg


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Discussion/conclusions (1)● Large uncertainty in emission of standing crops● Two parameters dominate the estimate:

– Ambient ammonia concentration (uncertainty < 10%)– Stomatal compensation point

› Γs values can range up to a factor of ten

● Focus should be on improving the Γs 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


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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


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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.


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One sentence summaryAmmonia 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: Γs values, got any?

Please let us know [email protected]


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

Documents

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