Description calculation of ammonia emission in the Netherlands
1. Gerard Velthof, National Emission Model Agriculture NEMA
2. Cor van Bruggen, Livestock manure production
3. Karin Groenestein, Ammonia emission from housing and manure storage
4. Jan Huijsmans, Ammonia emission from manure application
5. Gerard Velthof, Ammonia emission from grazing
6. Gerard Velthof, Ammonia emission from other sources
1
1. National Emission Model Agriculture NEMA
Gerard Velthof, Alterra WUR
Introduction
In 2009 an ammonia-inventory model for the Netherlands based on TAN (Total Ammoniacal
Nitrogen) was developed: NEMA (National Emission Model for Ammonia; Velthof et al., 2009).
In 2013, this model was extended with N2O, CH4, NOx, and fine particles (the name has been
changed into National Emission Model for Agriculture). The focus of this paper is on the
methodology to calculate ammonia emissions. NEMA calculates emissions at a national scale.
The emissions calculated using NEMA are reported by the Netherlands to the European
Commission (NEC Directive), UNECE (Gothenborg protocol), and UNFCCC (Kyoto protocol).
Method
The NEMA model is a TAN-based N flow model using emission factors (Figure 1; note that the
NEMA model was extended with ammonia emissions from compost, sewage sludge, crop
residues, and ripening of crops in 2014). The EMEP/EEA air pollutant emission inventory
guidebook recommends using a TAN-based approach (Tier 2 method) for calculation of
ammonia emission. NEMA uses a country specific TAN-based approach to calculate ammonia
emissions (Tier 3).
A TAN-based approach requires information on the excretion of TAN and changes in TAN
during storage of manure because of mineralization and immobilization of N. In NEMA, the
total N excretion and the fraction of TAN in the excreted N are calculated from the feed
composition and N digestibility of the feed components (see 2 pager Van Bruggen). This
annual calculation of the TAN excretion based on feed composition (derived from surveys) is a
main difference between NEMA and other TAN-based models, in which generally a fixed TAN
fraction in total N excretion is used.
TAN-based emission factors for ammonia have been derived or updated for housing systems
and manure storage outside housing (see 2 pager Groenestein; Groenestein et al., 2012),
manure application techniques (see 2 pager Huijsmans; Huijsmans et al., 2012), N fertilizer
types (see 2 pager Velthof), and grazing (see 2 pager Velthof).
Figure 1. General set-up of the NEMA model. The numbers indicate the flows of TAN and N
and the gaseous emissions in Gg N per year in 2009 (Velthof et al., 2009).
2
The NEMA working group of the Scientific Committee of the Manure Act calculates the
ammonia emissions yearly. Also they collect the data and emission factors needed for these
calculations. The NEMA working group includes experts from Statistics Netherlands, WUR
Livestock Research, PBL, RIVM, LEI WUR, Plant Sciences Group WUR, and Alterra-WUR. The
calculations are carried out by Statistics Netherlands. All input data and results are reported
annually (see the report series of Van Bruggen et al., 2011a&b, 2012, 2013, 2014; note that
the report Van Bruggen et al. (2012) is also available in English). The Netherlands Pollutant
Release and Transfer Register (PRTR) who is responsible for the emission data, publishes the
emissions and reports these emissions to European Commission and UN.
Results
Table 1 shows the total emissions in 2013 calculated with NEMA. Figure 1 shows the trend in
emission from 1990. Cleary, housing and manure application are the largest sources of
ammonia. The ammonia emission from manure application has strongly decreased in the
nineties, which is largely due to the obligation of low ammonia emission application
techniques.
Tabel 1. NH3 emission from agriculture in 2013 in
the Netherlands (mln kg NH3) calculated with
NEMA.
Housing
50.2
Outside storage of manure
3.0
Grazing
1.3
Manure application
39.7
Mineral fertilizer
13.6
Sewage sludge
0.1
Compost
0.4
Crop residues
2.3
Ripening crops
1.8
Total
112.3
Figure 1. Trend in ammonia emission from agriculture in the Netherlands in
the period 1990 – 2013 calculated with NEMA.
References
Velthof, G.L., C. van Bruggen, C.M. Groenestein, B.J. de Haan, M.W. Hoogeveen, J.F.M. Huijsmans
(2012) A model for inventory of ammonia emissions from agriculture in the Netherlands.
Atmospheric Environment 46, 248-255
Groenestein, C.M., Van Bruggen, C., De Haan, B.J., Hoogeveen, M.W., Huijsmans, J.F.M., Van De
Sluis, S.M., Velthof, G.L. 2012. Nema: dutch inventory of ammonia emissions from livestock
production and focus on housing and storage. Proceedings of EMILI, International Symposium
on Emission of Gas and Dust from Livestock, Saint-Malo, France – June 10-13–2012. 392-395.
Huijsmans, J.F.M., Vermeulen , G.D., Bussink, D.W., Groenestein, C.M. and Velthof, G.L., 2012.
Improved assessment of ammonia emission factors for field applied manure, fertilizers and
grazing in the Netherlands. Proceedings of EMILI, International Symposium on Emission of Gas
and Dust from Livestock, Saint-Malo, France – June 10-13–2012. 134 – 138.
Bruggen, van C., C.M. Groenestein, B.J. de Haan, M.W. Hoogeveen, J.F.M. Huijsmans, S.M. van der
Sluis& G.L. Velthof (2012) Ammonia emissions from animal manure and inorganic fertilisers in
2009. Calculated with the Dutch National Emissions Model for Ammonia (NEMA). Wettelijke
Onderzoekstaken Natuur & Milieu, WOt-werkdocument 302.
Velthof, G.L., C. van Bruggen, C.M. Groenestein, B.J. de Haan, M.W. Hoogeveen en J.F.M.
Huijsmans 2009. Methodiek voor berekening van ammoniakemissie uit de landbouw in
Nederland , Wageningen, Wettelijke Onderzoekstaken Natuur & Milieu, WOt-rapport 70. 180 blz
(In Dutch)
Annual report of emissions Van Bruggen et al. (2011a&b, 2012, 2013, 2014) In Dutch :. See:
http://www.wageningenur.nl/nl/Onderzoek-Resultaten/Projecten/Commissie-van-DeskundigenMeststoffenwet-CDM/Documenten/Ammoniakemissies.htm
3
2. Livestock manure production
Cor van Bruggen, Statistics Netherlands
Introduction
Since the early 1990s, the working group on livestock manure calculations (WUM) has been
identifying standard factors for manure production and nutrient excretions per livestock
category. The working group was established following the need for standardised data on
livestock manure production. Since 2006, the WUM has been part of the Pollutant Release and
Transfer Register (PRTR), a project in which a large number of organisations collaborate to
annually gather and determine emissions of pollutants to air, water and soil.
Method
Nitrogen and phosphate excretion factors are calculated annually based on a nutrient balance
per animal:
(nutrient excretion, kg/head.year) = (nutrient uptake from feed, kg/head.year) – (nutrient
fixation in animal products, kg/head.year).
The calculation methodology is based on Coppoolse et al. (1990). The basis of the calculation
of excretion factors consists of data on feed use (quantities of compound feed and roughage)
and animal production (milk, eggs, animal growth, and numbers of animal births). In addition,
data is required on N and P content in feed and in animal products. A distinction is made
between annually updated data such as milk yield and N and P content of feed and data that
remain steady for a number of years such as live weight of livestock categories. Annually
updated data are derived as much as possible from statistics and technical administrations of
the year in question. Other data have been updated regularly based on studies within the
framework of manure policy (Van der Hoek, 1987; Tamminga et al., 2000, 2004 and 2009;
Jongbloed and Kemme, 2005; Kemme et al., 2005a and 2005b) or other studies
commissioned by the WUM (Heeres-van der Tol, 2001; Evers et al., 2011).
A complete overview of the methodology and the results of 1990-2008 are described in WUM
(2010).
The nutrient excretion factors represent average factors for the Netherlands as a whole. The
only exception is cattle, for which calculations differentiate between two regions based on the
availability of grass silage and maize silage. Furthermore, a distinction is made between
housing and grazing time considering ammonia emissions.
The TAN excretion is calculated annually based on the nitrogen digestibility of roughage and
compound feed (Velthof et al., 2009, annex 7-9; Bikker et al., 2011) except for small
categories such as mink and rabbits.
Total excretion (N, TAN, P2O5, kg) per animal category is calculated as:
(number of animals in the agricultural census) x (excretion factor, kg/head.year).
In 2012 the methodology was reviewed by the Commission of Experts on the Manure act
(CDM, 2012). The overall conclusion was that the methodology together with corresponding
data sources make a complex model which generates accurate excretion factors for most
livestock categories which are representative for the Netherlands as a whole. For some small
livestock categories, the excretion factors are less accurate because of uncertainties in
farming systems, feed use and N and P content of live weight.
4
Results
Nitrogen excretion (kg/head.year) and TAN (%)
2000
N
TAN
Dairy cows
136.5
o.w.
housing season
71.0
62
grazing season-housing time
26.2
71
grazing season-grazing time
39.8
71
Fattening pigs
12.3
68
Sows
30.9
67
Laying hens
0.67
76
Broilers
0.51
70
2010
2013
N
130.2
TAN
N
128.7
TAN
68.1
39.8
22.3
12.2
30.2
0.80
0.50
59
64
64
68
66
74
67
67.9
41.3
19.5
12.0
29.3
0.75
0.45
58
65
65
68
63
77
63
References
Bikker, P., M.M. van Krimpen, G.J. Remmelink. (2010). Stikstofverteerbaarheid in voeders voor
Landbouwhuisdieren. Intern rapport. Livestock Research - Wageningen UR. Lelystad.
CBS (2011). Dierlijke mest en mineralen 2009 (C. van Bruggen). CBS, Den Haag/Heerlen.
http://www.cbs.nl/NR/rdonlyres/DAC00920-82AC-4E9F-8C01122F5721D627/0/20110c72pub.pdf
CBS (2012a). Dierlijke mest en mineralen 2010 (C. van Bruggen). CBS, Den Haag/Heerlen.
http://www.cbs.nl/NR/rdonlyres/67671376-6115-4267-A684-D5527431F528/0/2010c72pub.pdf
CBS (2012b). Dierlijke mest en mineralen 2011 (C. van Bruggen). CBS, Den Haag/Heerlen.
http://www.cbs.nl/NR/rdonlyres/C29000F7-4722-474E-BF26-82321CA55F1C/0/2012c72pub.pdf
CBS (2013). Dierlijke mest en mineralen 2012 (C. van Bruggen). CBS, Den Haag/Heerlen.
http://www.cbs.nl/NR/rdonlyres/39039B38-1E75-45E7-ABDFC74C213C224C/0/2013c72pub.pdf
Coppoolse, J., A.M. van Vuuren, J. Huisman, W.M.M.A. Janssen, A.W. Jongbloed, N.P. Lenis, P.C.M.
Simons. (1990). De uitscheiding van stikstof, fosfor en kalium door landbouwhuisdieren, Nu en
Morgen [excretions of nitrogen, phosphorus and potassium from domesticated farm animals,
present and future]. Wageningen, Dienst Landbouwkundig Onderzoek
Evers, A., B. Bosma, J. Heeres, H. Luesink, E. Schuiling, I. Vermeij. (2011). Update kengetallen
voor WUM. Rapport opdrachtgever 276. Wageningen UR Livestock Research. Lelystad.
Heeres-van der Tol, J.J. (2001). Vaste kengetallen rundvee, schapen en geiten herzien [revised
fixed index numbers cattle, sheep and goats]. Intern rapport 455. In opdracht van de
Werkgroep Berekening Mest- en Mineralencijfers (WUM). Praktijkonderzoek Veehouderij.
Lelystad.
Hoek, K.W. van der, (1987). Fosfaatproductienormen voor rundvee, varkens, kippen en kalkoenen
[phosphate production standards for cattle, pigs, chickens and turkeys]. Consulentschap in
Algemene Dienst voor Bodem, Water en Bemestingszaken in de Veehouderij.
Jongbloed A.W., P.A. Kemme, J.Th.M. van Diepen and J. Kogut, 2002a. De gehalten aan stikstof,
fosfor en kalium in varkens vanaf geboorte tot ca. 120 kg lichaamsgewicht en van opfokzeugen
[content of nitrogen, phosphorus and potassium in pigs from birth up to ca 120 kg body weight
and in gilts]. ID-Lelystad rapport no. 2222.
Jongbloed, A.W., P.A. Kemme, 2002b. Oriëntatie omtrent de gehalten aan stikstof, fosfor en kalium
in landbouwhuisdieren [orientation regarding the content of nitrogen, phosphorus and
potassium in domesticated farm animals]. ID-Lelystad rapport no. 2178.
Jongbloed, A.W., P.A. Kemme. (2005). De uitscheiding van stikstof en fosfor door varkens, kippen,
kalkoenen, pelsdieren, eenden, konijnen en parelhoenders in 2002 en 2006 [excretion of
nitrogen and phosphorus from pigs, chickens, turkeys, ducks, rabbits and guinea fowls in 2002
and 2006]. Rapport 05/I01077. Animal Sciences Group - Nutrition and Food, Lelystad.
Tamminga, S., A.W. Jongbloed, M.M. van Eerdt, H.F.M. Aarts, F. Mandersloot, N.J.P. Hoogervorst
and H. Westhoek. (2000). De forfaitaire excretie van stikstof door landbouwhuisdieren [fixed
nitrogen excretion from domesticated farm animals]. Rapport ID Lelystad 00-2040R.
Tamminga, S., F. Aarts, A. Bannink, O. Oenema, G.J. Monteny. (2004). Actualisering van geschatte
N en P excreties door rundvee [update of estimated N and P excretion from cattle]. Reeks Milieu
en Landelijk gebied 25. Wageningen.
Tamminga, S. A.W. Jongbloed, P. Bikker, L. Šebek, C. van Bruggen, O. Oenema. (2009).
Actualisatie excretiecijfers landbouwhuisdieren voor forfaits regeling Meststoffenwet [update of
data on excretions from domesticated farm animals for the regulation on fixed amounts under
5
the Fertiliser Act]. Werkdocument 156 Wageningen, 2009.
http://www.wageningenur.nl/upload_mm/6/1/1/d1059e4e-27de-4cc9-9b3c-9995f89a9582_12444.pdf
Velthof, G.L., van Bruggen, C., Groenestein, C.M., de Haan, B.J. Hoogeveen, M.W., Huijsmans,
J.F.M. (2009). Methodiek voor berekening van ammoniakemissie uit de landbouw in Nederland.
WOt-rapport 70, Wageningen. http://www.wageningenur.nl/upload_mm/d/d/4/97c587ef-c79d-4ac9-94e48d2dfb38431d_5140.pdf
WUM (2010). Standardised calculation methods for animal manure and nutrients. Standard data
1990–2008. working group on livestock manure calculations (edited by C. van Bruggen). CBS,
PBL, LEI-Wageningen UR, Wageningen UR-Livestock Research, Ministry of Agriculture and RIVM.
CBS, The Hague. http://www.cbs.nl/nlnl/menu/themas/landbouw/publicaties/publicaties/archief/2012/2012-standarised-caculationanimal-manure-2008.htm
6
3. Ammonia emission from housing and manure storage
Karin Groenestein, WUR Livestock Research
Introduction
As pointed out by Gerard Velthof NEMA is a TAN-flow model which is a Tier 3 model, as are
the models of Germany, Switzerland, Austria, Denmark and the United Kingdom. By and large
this comes down to an estimation of the amount of TAN excreted by the animals (explained
by Cor van Bruggen) and the emission factor, being the fraction of N lost as aerial compound
during housing, storage and application of fertilizer. The Eager working group compares the
different European Tier 3 ammonia emission models and concluded that with the same
activity data the models gave similar results (Reidy et al., 2007) and the differences between
countries are mainly caused by differences in TAN-excretion and the emission factors as a
percentage of TAN. The quality of the data determines the quality of the estimates. This
chapter focuses on the ammonia emission factors during storage and animal housing and how
these factors are estimated in the Netherlands.
Method
Storage
We distinguish emissions from manure storage in livestock buildings (housing) and storages
outside the livestock building (storage). Outside the building manure is stored in silos or,
when it is solid, on heaps. So we defined emission factors for stored slurry and solid manure
in the house and stored outside. The slurry silos are obligatory covered, and therefore the
emission factor has decreased 90% compared to the early nineties, when efforts to reduce
ammonia emission started. The emission factor is derived from a study on mini silos from de
Bode (1990). In the Netherlands cattle and pig produce mainly slurry, while poultry produces
solid manure. The latter is hardly stored outside. Manure stored outside in the Netherlands is
thus mainly slurry in covered silos and the share of slurry storage outside compared to
storage in the house is approximately 25%.
The ammonia-emission factor of the outside storage is expressed as the amount of TAN
leaving the house, so excluding all the N-losses in the house and considering mineralization of
organic N and/or immobilisation of TAN.
Housing
The manure in the house is stored on the floor (e.g. poultry) or underneath slatted floors in
slurry pits (e.g. cattle and pigs). The Netherlands have a legal Regulation ammonia and
livestock husbandry, which comprise in total 12 animal categories, from cattle to horses and
ostriches. Within these categories, subcategories are defined. For example in cattle there are
seven subcategories, from dairy to young cattle and suckling cows, for pigs five and for
poultry also five, including layers, broilers and parental animals. In total 38 animal
subcategories are defined.
Per animal subcategory a reference housing system is defined. When a housing type or
technique is considered low enough in ammonia emission (ca 50% of the reference), it is
adopted with an emission factor in the Regulatory. So, in 1990 we started with 30 emission
factors for the three main animal categories cattle, pigs and poultry, we now have more than
400 emission factors for 11 animal categories (Infomil, 2015)
Over the years we have had several measurement campaigns to establish emission factors for
housing systems and other reducing techniques (e.g. scrapers, scrubbers, drying tunnels). To
measure effectively and representatively, we developed a measuring protocol in 1996. This
protocol included long-term measurements during summer and winter on one farm given
certain livestock management standards. After 10 years, numerous measurements and
improved knowledge on the factors and processes involved in production and volatilisation of
ammonia, we could analyse our data statistically to develop a new, better protocol. This
included six 24 hour-measurements during a year, (semi)randomly picked, covering all
seasons and growth phases) at four different farms. Mosquera et al. (2014) give elaborate
information on available and preferred measurement methods.
7
Because it is too costly to measure all farming systems, some emissions in the Regulatory
were deduced from the measured ones. Factors considered to support deduction were mainly
TAN, (fouled) surface area, urea, aeration, temperature and grazing period. Improved
knowledge on influencing factors and changes of animal and manure management were
reasons to update emission data. Therefore new measurements were done in 2010 and new
deductions were made resulting in revised emissions in the Regulatory for cattle (Ogink etal.,
2014) and pigs (Groenestein etal., 2014). In 2015 we will finish the update of the poultry
data.
NEMA uses the emissions in the Regulation ammonia and husbandry to calculate the emission
factor of the housing unless better scientific data are available. The NH3-N emission is then
expressed as a percentage of the average TAN of the animal subcategorie in the year the
measurements were done.
The degree of implementation of the different housing systems is derived from an annual
census and from environmental permits based on ammonia emission farmers have to apply
for, referring to an administrative number as published at Infomil (2015). For example, the
permit with the number D 3.2.9.2 defines housing for fatteners with a chemical air scrubber
with an efficiency of ammonia removal of 70% and a living surface area of more than 0.8 m2
per animal.
Results
The annual census to determine implied housing systems in the Netherlands is not a sample
survey, but actually comprises all Dutch farms. The implementation degree is estimated by a
sample, but this sample comprises almost half of the Netherlands. It is safe to state that the
estimates of these activity data are rather accurate.
The emission factors are measured or deduced based on expert knowledge. As mentioned in
the 2 pager of Velthof, NEMA is updated yearly, as are the emission factors and the share of
the various housing and storage systems in the Netherlands. The resulting emission factors
are published yearly, like in Bruggen et al., 2012 (Table 4.1) or more recent (but in Dutch):
Bruggen et al., 2014 (Table 2.9 en 2.11). The Tables 2.5-2.8 give respectively the share of
housing systems for cattle, pigs, poultry and additional techniques to reduce emissions like
drying tunnels.
Housing and storage contribute ca 50% to the total NH3 emission in the Netherlands, of which
5% is from storage and 95% from housing (Table 4.2 in Bruggen et al (2012) and Table 6.1
in Bruggen et al. (2014).
Since 1990 total ammonia emission in the Netherlands reduced with 70%. Ammonia emission
from housing and storage reduced with only 40%. Of cattle, pigs and poultry, pigs housing
and storage emission reduced the most (57%), partly by reducing the area of the emitting
surface and because of air scrubbers (ca 40% of the pigs). Cattle’s housing and storage
emission reduced 28%, not as much with housing techniques, but mainly because of
reduction of TAN excretion (incentive was Nitrates Directive). For poultry housing and storage
emission reduced 27% mainly because of techniques to dry the manure.
References
Bode, M.J.C. de (1990) Emissie van ammoniak en geur uit mestsilo’s en de vermindering van
emissie door afdekking. Nota IMAG nr 465.
Bruggen, van C., C.M. Groenestein, B.J. de Haan, M.W. Hoogeveen, J.F.M. Huijsmans, S.M. van der
Sluis& G.L. Velthof (2012) Ammonia emissions from animal manure and inorganic fertilisers in
2009. Calculated with the Dutch National Emissions Model for Ammonia (NEMA). Wettelijke
Onderzoekstaken Natuur & Milieu, WOt-werkdocument 302.
Bruggen, C. van; Bannink, A.; Groenestein, C.M.; Haan, B.J. de; Huijsmans, J.F.M.; Luesink, H.H.;
Sluis, S.M.; Velthof, G.L.; Vonk, J., 2014. Emissies naar lucht uit de landbouw in 2012 :
8
berekeningen van ammoniak, stikstofoxide, lachgas, methaan en fijn stof met het model NEMA,
Wettelijke Onderzoekstaken Natuur & Milieu, Wageningen. http://edepot.wur.nl/299687
Groenestein, C.M., Aarnink, A.J.A., Ogink, N.W.M. (2014) Actualisering ammoniakemissiefactoren
vleesvarkens en biggen : advies herberekening op basis van welzijnseisen Wageningen UR
Livestock Research Report 786 - p. 24. http://edepot.wur.nl/318846
Mosquera, J., N. Edouard, F. Guiziou, R.W. Melse, A.L. Riis, S. Sommer, E. Brusselman (2014).
Decision document on the revision of the VERA protocol on air cleaning technologies. Measuring
techniques for the determination of the removal efficiency for ammonia. Wageningen UR Livestock
Research Report 767 – p. 51 http://edepot.wur.nl/311017
Ogink, N.W.M., C.M. Groenestein, J. Mosquera, (2014) Effects of changes in management and
feeding practices on the ammonia emission factor of dairy cattle in the Netherlands
In: Proceedings International Conference of Agricultural Engineering. - European Society of
Agricultural Engineers (EurAgEng), AgEng 2014, Zurich, Switzerland, 2014-07-06/ 2014-07-10 - p.
1 - 7. http://www.geyseco.es/geystiona/adjs/comunicaciones/304/C04990001.pdf
Infomil, 2015. Knowledge Centre of the Ministry of Infrastructure and Environment,
http://www.infomil.nl/onderwerpen/landbouw-tuinbouw/ammoniak/rav/stalbeschrijvingen/
B. Reidy, B., U. Dämmgen, H. Döhler, B. Eurich-Menden, F.K. van Evert, N.J. Hutchings, H.H.
Luesink, H. Menzi, T.H. Misselbrook, G.-J. Monteny, 2007. Comparison of models used for national
agricultural ammonia emission inventories in Europe: Liquid manure systems. Atmospheric
Environment 42, (14): 3452–3464
http://www.sciencedirect.com/science/article/pii/S1352231007003469
9
4. Ammonia emission factors for manure application in the Netherlands
Jan Huijsmans, Plant Research WUR
Introduction
In the NEMA model, the NH3 emission from each source is described by an emission factor
(EF). For manure application, EF is defined as the amount of total ammoniacal nitrogen (TAN)
lost by volatilization expressed in percentage of the total field-applied TAN in the manure.
Before and in the beginning of the 1990’s the EF for manure application was estimated on
expert judgement. Since the 1990’s data from field experiments on grassland and arable land
in the Netherlands became available and EF’s were derived for various manure application
methods. Field studies were mainly carried out with the micro meteorological mass balance
method (also named IHF).
Method and EF derivation
In field studies the NH3 emission reduction was assessed for various technical methods to
reduce the volatilization of field-applied manure on grassland and arable land. These methods
included acidifying, use of additives, diluting, irrigating manure and different methods for
placement of the manure in or on top of the crop or soil. The ammonia emission from
broadcast surface spreading of manure was included as the reference in these experiments.
From 1995 onwards legally accepted low-emission methods in the Netherlands were grouped
into application methods with similar positioning of the manure on or into the soil. For manure
application on grassland these legally accepted methods were narrow-band application and
shallow injection and for manure application on arable land (direct) surface incorporation,
shallow injection and deep placement (mostly carried out by injection).
Since the introduction of the legal policies for manure application methods still some
measurements on ammonia emission were carried out for further underpinning of EF’s.
Results
Grassland
The first emission results of the experiments on grassland were internationally presented and
published in 1994-1997 including data from nitric acid treated slurry (1) and deep injection on
grassland (2). In 2001 the set of data at that moment was analysed and published (3). The
emission data from the Dutch experiments on grassland (3) were used in a European context
for an analysis of all European data on ammonia emission to reveal effects of methods of
application, weather, soil and manure characteristics and measurement techniques used (EUALFAM project 4). At a later stage joint research between Belgium and the Netherlands was
carried out to assess ammonia emissions from common application techniques in both
countries (5).
Arable land
The data of the emission experiments with various manure application methods on arable land
were published in 2003 (6). The emission for surface incorporation was based on the emission
data for surface-spreading, directly followed by incorporation of the manure into the topsoil by
various cultivators, i.e. with rigid tines, spring tines or discs. However, as high volatilization
rates occur shortly after application, the reduction achieved by incorporation highly depends on
the time-lag between surface spreading and incorporation (7). For this reason, the EF’s for
incorporation in two passes were estimated as the average EF’s for surface spreading and direct
incorporation.
EF’s
The publications for manure application on grassland and arable land were also published as
PhD thesis (8). The data were partly used to determine the EF’s in inventory studies till 2007
and it became clear that the EF’s needed to be reassessed (9). In 2008-2009 a reassessment
of all EF’s from agricultural sources was carried out for a national evaluation of low emission
manure application and the occasion of the introduction of the NEMA model for the
assessment of national emissions. The most recent EF’s for manure application on grassland
are based on an extended set of experimental data, including those after 1997. Also, both for
grassland as for arable land, possible trends in the emission with time are accounted for and
10
the statistical method applied to determine the EF’s for the different application methods has
been improved (10). The total number of observations used for the reassessment of the EF’s
was 199 on grassland, of which 81 for surface spreading, 29 for narrow band application and
89 for shallow injection. Similarly, 58 observations were used for arable land, of which 26 for
surface spreading, 25 for surface incorporation and 7 for deep placement.
For the contribution of manure application to the national emissions, the implementation of
the share of different application techniques is derived from the Farm Structure Survey (FSS)
2010.
Discussion and on-going research and developments
Single average EF’s per application method were justified, as all NH3 emission experiments
were carried out during the usual manure application periods, using manure as available; the
experimental conditions were considered representative for the conditions in practise in the
Netherlands.
The average EF’s are used in national inventories and decision making without distinction
between manure and field characteristics or weather conditions, despite their demonstrated
effects (3, 6). It is interesting to note that the years during which the low-emission techniques
became compulsory in the Netherlands, coincided with the establishment of a spreading ban
during autumn and winter in order to reduce leaching losses of N. This shifted the spreading
times to the warmer and drier growing season which may, as such, have stimulated the
emission of NH3 (3, 6).
International discussions on the accuracy of measuring methods and on the understanding of
the variation in emissions from field-applied manure let to an international review in 2013 on
EF’s for manure application in the Netherlands. This review was followed up by the initiation of
new research in which the accuracy of the measuring method is discussed, but moreover the
addressing of a quantitative understanding of the variations in the height of the emissions.
The latter is taken aboard in a joint research of RIVM and WUR addressing mechanistic and
empirical modelling of the emission process. For the mechanistic modelling the Volt’air
approach is considered and is now in discussion with INRA France with the first results ( 11).
The empirical modelling is carried out on the national data of all field experiments and also in
a joint international collaboration (“ALFAM 2 consortium”). Preliminary runs with the empirical
model for the weather conditions over the past 20 years clearly show the different EF’s per
month (with their variations over the years) and effects of manure characteristics and soil on
the EF. The quantitative understanding of the variations in the height of the emissions may
lead to a differentiation of EF’s to for instance soil type, manure characteristics and weather
conditions during common manure application periods. This differentiation may lead to an EF
at farm scale, and to weighted EF’s on national scale. The latter is only feasible if data on
manure application practices is available or can be estimated. In the FSS 2015 special
attention is given to the implementation of manure application methods in relation to the soil
type and land use. Presently, narrow band application on sandy grassland, and the application
and incorporation of liquid manure in two passes is not allowed anymore in the Netherlands.
References
1. Bussink, D.W., J.F.M. Huijsmans & J.J.M.H. Ketelaars, 1994. Ammonia volatilization from
nitric-acid-treated cattle slurry, (surface) applied to grassland. Netherlands Journal of
Agricultural Science 42: 293-309.
2. Huijsmans, J.F.M., J.M.G. Hol & B.W. Bussink, 1997. Reduction of Ammonia Emission by
New Slurry Application Techniques on Grassland. In: S.C. Jarvis & B.F. Pain (Eds.) Gaseous
Nitrogen Emissions from Grasslands. CAB International, Wallingford, pp. 281-285.
3. Huijsmans, J.F.M., J.M.G. Hol & M.M.W.B. Hendriks, 2001. Effect of application technique,
manure characteristics, weather and field conditions on ammonia volatilization from
manure applied to grassland. Netherlands Journal of Agricultural Science 49: 323-342.
http://dx.doi.org/10.1016/s1573-5214(01)80021-x
4. Søgaard, H.T., S.G. Sommer, N.J. Hutchings, J.F.M. Huijsmans, D.W. Bussink & F.
Nicholson, 2002. Ammonia volatilization from field-applied animal slurry - the ALFAM
model. Atmospheric Environment 36: 3309-3319.
11
5. Huijsmans, J.F.M., G.D. Vermeulen, J.M.G. Hol, H. Cnockaert & P. Demeyer, 2007. Effect of
application method on ammonia volatilization from manure applied to grassland in the
Netherlands and Belgium. In: G.J. Monteny and E. Hartung (Eds.) Ammonia emissions in
agriculture. Wageningen Academic Publishers, The Netherlands, pp. 191-193.
6. Huijsmans, J.F.M., J.M.G. Hol & G.D. Vermeulen, 2003. Effect of application method,
manure characteristics, weather and field conditions on ammonia volatilization from
manure applied to arable land. Atmospheric Environment 37: 3669-3680.
7. Huijsmans, J.F.M. & R.M. De Mol, 1999. A model for ammonia volatilization after surface
application and subsequent incorporation of manure on arable land. Journal of Agricultural
Engineering Research 74: 73-82. http://dx.doi.org/10.1006/jaer.1999.0438
8. Huijsmans, J.F.M. 2003. Manure application and ammonia volatilization. PhD thesis
Wageningen University with summaries in English and Dutch, Wageningen, The
Netherlands, ISBN 90-5808-937-1, pp 160.
9. Aarnink, J.A., H.H. Ellen, J.F.M. Huijsmans, M.C.J. Smits & D.A.J. Starmans, 2007.
Emission abatement in practical situations, paragraph Emissions after manure application.
In: D.A.J. Starmans and K.W. van der Hoek (Eds.) Ammonia, the case of The Netherlands.
Wageningen Academic Publishers, The Netherlands, pp. 87-92.
10. Huijsmans, J.F.M. & R.L.M. Schils (2009). Ammonia and nitrous oxide emissions
following field-application of manure: state of the art measurements in the
Netherlands, Proceedings 655, International Fertiliser Society, 35 pp.
11. Huijsmans, J.F.M. Holterman, H.J., Vermeulen, G.D., Stolk, A.J. & Pul, W.A.J. van,
2014. Simulating emission of ammonia after liquid manure applicaton on arable
land: Preliminary performance assessment of the Volt'air model for manure
application conditions in the Netherlands, Wageningen UR, Wageningen, The
Netherlands, 42 pp.
12
5. Ammonia emission from grazing
Gerard Velthof, Alterra WUR
Introduction
This paper describes the method to calculate the ammonia emission from grazing. Based on
the measurements of Bussink (1992, 1994, 1996), a fixed emission factor of 8% of total N for
grazing was used until recently. A similar value is used in inventory models used by other
countries. However, because of the decreasing N application rates (implementation Nitrates
Directive), the N content of grazed grass has decreased strongly (from 32.9 to 24.9 g N kg-1
dry matter in the 1992-2013 period). This will also lead to smaller NH3 emission from grazed
grassland. There are no recent measurements for NH3 emission during grazing at low N
application rates.
Method
The results of the experiments of Bussink at different application rates have been used to
derive a TAN-based emission factor for grazing. The data by Bussink were reprocessed to
correct for the NH3 emission caused by the applied fertilizer, to correct for the change from
continuous to restrictive grazing, and to derive an empirical model to estimate the emission
factor for grazing in dependence of the feed N content and the cation exchange capacity (CEC
of the soil (Table 1).
Currently, grazing is mostly restricted to daytime in the Netherlands. Based on measured
emission fluxes of Bussink (1992), for continuous and restricted grazing it was estimated that
restricted grazing results in a 1.2 times higher emission factor than continuous grazing,
resulting in emission factors for restricted grazing of 4.0-11.7%. Corrections for soil type were
made using correction factors of Bussink (1996) for CEC, and the Dutch soil map (15% of the
grassland is on peat, 47% on sand and 39% on clay and loess). An empirical relationship
between N content in the feed and NH3 emission factors has been derived and applied to
calculate the emission factor using the data of feed composition yearly (Figure 1).
Table 1. Emission factors for grazing on calcareous soil based on Bussink (1992,
1994). Table from Huijsmans et al., 2012)
However, the current N (24.9 g N kg-1 dry matter in 2013) is in the extrapolated area of the
empirical expression in Figure 1. Therefore, the emission factor is (arbitrarily) fixed at a 2.6%
for N contents of the less than 25 g N kg-1 dry matter. In the Netherlands no measurement data
are available for NH3 emission from grazing in other grazing animal species (other cattle, horses,
ponies and sheep). The formula for dairy cattle are also used for other grazing animals.
13
Figure 1. Relation between N content grass and emission factor, based on Bussink (1992,
1994, 1996)
Results
Application of the formula indicated in Figure 1, using the average N content of feed during
grazing (see 2 pager Van Bruggen) results in a strongly decreasing emission factor for
grazing, which is kept at 2.6 % during the recent year (Figure 2). This emission factor is
much smaller than emission factors for grazing used in other models, which are generally also
derived from the studies of Bussink.
Figure 2. Trend in emission factor for grazing.
References
Bussink, D.W., 1996. Ammonia volatilization from intensively managed dairy pastures. PhD thesis
Wageningen University, 177 pp. http://edepot.wur.nl/202219 (including the papers:
Bussink, D.W., 1992. Ammonia volatilisation from grassland receiving nitrogen fertiliser and
rotationally grazed by dairy cattle. Fertiliser Research 33, 257-265.
Bussink, D.W., 1994. Relationship between ammonia volatilisation and nitrogen fertiliser
application rate, intake and excretion of herbage N by cattle on grazed swards. Fertiliser
Research 38, 111-121.
Huijsmans, J.F.M., Vermeulen , G.D., Bussink, D.W., Groenestein, C.M. and Velthof, G.L., 2012.
Improved assessment of ammonia emission factors for field applied manure, fertilizers and
grazing in the Netherlands. Proceedings of EMILI, International Symposium on Emission of Gas
and Dust from Livestock, Saint-Malo, France – June 10-13–2012. 134 – 138.
14
6. Ammonia emission from other sources
Gerard Velthof, Alterra WUR
Introduction
Field data on NH3 emission after fertilizer application in the Netherlands are insufficient to
derive emission factors. Therefore, the emission factors for average conditions in the
Netherlands were based on analysis of international data for fertilizers and the derived
statistical model by Bouwman et al. (2002). Bouwman et al. (2002) used 148 studies (1,667
ammonia measurements) from all over the world to quantify the effect of fertilizer type, crop,
N addition, application method, temperature, soil characteristics (cation exchange capacity
(CEC), pH, organic matter content) and location. There are no data of NH3 emission from
compost and sewage sludge and therefore assumptions are made to estimate NH3 emissions.
Ammonia emission from crop residues and ripening crops are derived from studies of De
Ruijter and Huijsmans (2012) and De Ruijter et al. (2013).
Method
Mineral fertilizers
Main factors affecting the NH3 emission from fertilizers in the Netherlands are land use,
fertiliser type, pH of the soil and CEC of the various soil types (Huijsmans et al., 2012; Velthof
et al., 2009). Bouwman et al. (2002) distinguish land uses as “grassland” and “upland crops”
and various pH classes of the soil. Arable land and maize land were defined as “upland crop”.
For the Netherlands, low CaCO3 (pH < 7.3) and rich CaCO3 (calcareous) soils (pH > 7.3) were
distinguished using the soil map, which showed that 13% of grassland soils, 9% of maize
land, and 49% of arable land are calcareous. Of all agricultural land, 24% is calcareous. To
match the categories with the pH categories of Bouwman et al. (2002), it was assumed that
half of the low CaCO3 soils had a pH lower than 5.5, and the other half had a pH of 5.5-7.3,
and the calcareous soils had a pH of 7.3-8.5. Based on soil analytical data over the 20072008 period, mean CEC was 70 mmolc kg-1 for sandy soils, 180 mmolc kg-1 for clay and loess
soils and 300 mmolc kg-1 for peat and reclaimed peat soils. Based on the relative areas of the
soil types in the Netherlands, the area weighted CEC for grassland was 146 mmolc kg-1 and
for arable land 134 mmolc kg-1. Using these estimates, the emission factors of various
fertilizer types used in the Netherlands were derived.
Compost and sewage sludge
Amounts of organic (household) waste and green refuse compost and sewage sludge are
available from Statistics Netherlands (CBS). The percentage of TAN in total N of compost
(9%) is taken from the data used for Fertilizer recommendations (www.kennisakker.nl). The
percentage of TAN in sewage sludge is calculated from German data on N and TAN contents of
liquid and solid sewage sludge (Anonymous, 2007). All compost is assumed to be applied to
cropland, using surface spreading. The liquid sewage sludge in applied with sod-injector and
solid sewage sludge is surface-applied and incorporated in a second track. The corresponding
emission factor for manure application (see 2 pager Huijsmans) is used.
Crop residues and ripening of crops
To calculate the percentage of N that volatilizes from crop residues, a regression model has
been derived from literature describing the relationship between ammonia emission and the N
content of residues (De Ruijter and Huijsmans, 2012): % volatilization = 0.40 * N content 5.08. The N content is the N contained in crop residue per crop in g/kg dry matter. No
emission occurs if N content is below 12.7 g/kg and the model assumes complete exposure to
air, both in amounts of residue and time. Areas of cultivated crops have been derived from
the agricultural census. For the N contents of crop residues for grass data of the working
group on livestock manure calculations (WUM; see Van Bruggen) have been used. Crop
residues also occur in the cutting, drying and collection of grass for the production of silage or
hay and an average loss of 1,000 kg dry matter/ha/year is assumed. Pasture topping is not
considered separately, but is accounted for in the emission factor for grazing (De Ruijter et
al., 2013).
15
For calculation of ripening standing crops a resistance model (DEPAC) was used, taking
regional differences in weather conditions and atmospheric conditions into account. This
includes the total NH3 emission from crops from sowing to harvesting.
Results
Table 1 shows the emission factor for major mineral N fertilizer used in the Netherlands.
Table 1. Average emission factors (% of N applied) for the major fertilizers in
the Netherlands, calculated with the method by Bouwman et al. (2002).
For compost and sewage sludge the emission factor for manure is used (see 2 pager
Huijsmans). Table 2 shows the emissions factors for crop residues for a selection of crops.
The total NH3 emission in the Netherlands from standing ripening crops was calculated by De
Ruijter et al. (2013) at 1.5 million kg NH3.
Table 2. N content and NH3 emission factors in crop residues for selected crops.
Crop
Green peas
Seed potatoes
Consumption and starch potatoes
Sugar beet
Endive
Asparagus
Cauliflower
Broccoli
Lettuce
Leek
Dpinach
Brussels Sprouts
Carrots
N in crop residue,
kg N per ha
47
85
31.5
120
40
27
132
156
37
82
30
170
9
Emission factor NH3-N,
% of N in crop residue
4.92
5.79
0.84
1.44
1.63
6.52
5.59
5.83
2.2
7.32
1.21
3.32
0.14
References
Anonymous. 2007. Hühnertrockenkot entlastet Düngerkonto (in German). Landwirtschaftliches
Wochenblatt 28. p. 24-26
Bouwman A.F.. L.J.M. Bouman & N.H. Batjes. 2002. Estimation of global NH3 volatilization loss
from synthetic fertilizers and animal manure applied to arable lands and grasslands. Glob.
Biogeochem. Cycl.. vol.16. No.2. 1024
De Ruijter. F.J. & 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. http://edepot.wur.nl/213704
De Ruijter. F.J.. 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. http://edepot.wur.nl/290558
Huijsmans. J.F.M.. Vermeulen . G.D.. Bussink. D.W.. Groenestein. C.M. and Velthof. G.L.. 2012.
Improved assessment of ammonia emission factors for field applied manure. fertilizers and
grazing in the Netherlands. Proceedings of EMILI. International Symposium on Emission of Gas
and Dust from Livestock. Saint-Malo. France – June 10-13–2012. 134 – 138.
Velthof. G.L.. C. van Bruggen. C.M. Groenestein. B.J. de Haan. M.W. Hoogeveen en J.F.M.
Huijsmans 2009. Methodiek voor berekening van ammoniakemissie uit de landbouw in
Nederland . Wageningen. Wettelijke Onderzoekstaken Natuur & Milieu. WOt-rapport 70. 180 blz
(In Dutch)
16