8.2 FIELD SCALE MEASUREMENTS OF NH3 EMISSIONS AFTER ORGANIC FERTILIZER APPLICATION: COMPARISON OF DIFFERENT METHODS

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1 8.2 FIELD SCALE MEASUREMENTS OF NH3 EMISSIONS AFTER ORGANIC FERTILIZER APPLICATION: COMPARISON OF DIFFERENT METHODS Christoph Spirig 1,2, *, Jörg Sintermnn 1, Christof Ammnn 1, Uwe Kuhn 1, nd Albrecht Neftel 1 1) Agroscope Reckenholz-Tänikon Reserch Sttion ART, Zurich, Switzerlnd 2) Federl Office for Meteorology nd Climtology MeteoSwiss, Zurich, Switzerlnd 1. INTRODUCTION As prt of the EU 6 th frmework project NitroEurope ( we imed t mesuring the complete set of nitrogen exchnge bove mnged grsslnd site in Switzerlnd. In this frmework we monitored the mmoni (NH 3 ) exchnge over two growing sesons with the erodynmic grdient method using two AiRRmoni monitors (Spirig et l., 21). The mesurements covered lso six pplictions of liquid cttle slurry by brod spreding, cusing high NH 3 emissions which ultimtely dominted the yerly mmoni exchnge t this site (Flechrd et l., 21). Still, the cumultive emissions fter slurry ppliction (in the order of 15% of pplied mmonicl nitrogen) were roughly three times lower thn the emission fctors in the ntionl emission inventory (Reidy et l., 28). A wide rnge (5-7% of pplied nitrogen), of emission fctors hs been reported, depending on meteorologicl conditions, the chrcteristics of the mnure, nd the technique used for ppliction (e.g. Pin et l., 1989, Søgrd et l. 22, Misselbrook et l., 25, Rochette et l., 28). But even for similr conditions, lrge rnge of emission fctors cn be found in the literture, reflecting considerble uncertinty. Prt of the uncertinty is relted to the lck of NH 3 flux mesurements fter fertiliztion t the scle of whole griculturl fields. Such mesurements still represent chllenge, minly becuse of the sticky nture of the NH 3 molecule, which complictes mesurements t high time resolution tht re needed for observing the highly dynmic chrcter of these emission events. Due to the difficulties of directly mesuring these NH 3 fluxes t the scle of whole griculturl fields, previous emission studies re * Corresponding uthor ddress: Christoph Spirig, MeteoSwiss, Krähbühlstr. 58, CH-844 Zurich, Switzerlnd; e-mil: christoph.spirig@meteoswiss.ch dominted by experiments on smller plots using pproches requiring NH 3 mesurements only t low time resolutions. However, it hs been shown tht the emissions from fertilized surfce scle with its extension, similr to evportion being lrger over n osis s compred to tht over lrger wter bodies (Génermont nd Cellier, 1997). As consequence, it is importnt to quntify NH3 emissions fter fertiliztion on representtive field sizes. Here we report on n experiment performed in summer 29, iming t quntifying emissions of NH 3 fter fertiliztion using different mesurement pproches. 2. EXPERIMENTAL 2.1 Field site nd fertiliztion The experiments were performed in August 29 t the NitroEurope site in Oensingen, Switzerlnd (Ammnn et l., 27). Liquid cttle slurry ws pplied on previously hrvested whet field on nd on grss field on (lso cut shortly before fertilizing). Six (whet field) nd three tnks(grss field) of slurry were spred with splsh plte device. The refilling nd trnsport of the liquid mnure triler from the frm to the field took 15-2 minutes. Hence it took bout 2.5 nd bit more thn one hour, respectively, to completely fertilize the fields. 2.2 Eddy covrince mesurements with etr-ms An electron trnsfer rection mss spectrometer (etr-ms) ws used for fst mesurements of NH 3. While it hs previously been reported tht this instrument is cpble of ccurtely mesuring NH 3 over wide rnge of concentrtions, it hs lso been noted tht time resolution ws limited nd fr wy for pplictions in eddy covrince mesurements

2 due to bsorptive effects of NH 3 within the instrument (Normn et l., 27, 29). A new vrint of the instrument ws used here, consisting of drift tube with PEEK (polyetherethylketone) insted of PFA teflon, llowing the heting of ll inner surfces of the mss spectrometer to 18 C. Operting the instrument t this temperture significntly improved the time response for NH 3 mesurements (Sintermnn et l., 21), potentilly fst enough for eddy covrince (EC) pplictions. etr-ms is lso cpble of mesuring wter vpor t sufficient time resolution for EC mesurements, s demonstrted by Ammnn et l. (26). The etr-ms ws operted in n ir-conditioned triler, thus requiring more thn 2m long tube for smpling ir directly below sonic nemometer (HS, Gill instruments, Lymington, UK). In order to reduce the ttenution of fst concentrtion chnges, ½ OD PFA Teflon tube with flow of 1 STP l min -1 ws used, nd we equipped it with custom mde heter to control it t temperture of 15 C. Detils bout the clcultion of fluxes from the etr-ms mesurements using the EC technique re described in Sintermnn et l. (to be submitted to Atmos. Mes. Tech. Discuss.). In short, the dt processing followed the methods pplied by Spirig et l. (25) nd Ammnn et l. (26, 21), llowing n integrl quntifiction nd correction of high frequency losses bsed on comprison of the cospectr (ogive nlysis) of verticl wind speed with temperture nd NH 3, respectively. 2.3 Aerodynmic Grdient mesurements Two Airrmoni (Mechtronics, NL) monitors were operted in grdient configurtion for simultneously mesuring NH 3 t heights of.45 nd 1.5 m t hlf hourly time resolution. These mesurements were used to derive fluxes using the erodynmic grdient method (AGM). Detils bout this system nd the flux clcultions re discussed in Spirig et l. (21). The AGM system ws operted on smll wgon tht could be wheeled onto the field immeditely fter the pssge of the slurry tnk. Still, the mesurement of initil fluxes ws usully not possible with this instrument due to sensor sturtion effects nd violtion of the homogenous footprint requirement during the slurry spreding. 2.4 Open pth FTIR mesurements On contrctul bsis n independent mss blnce pproch using three identiclly configured open-pth FTIR-spectrometers (K3; Kyser- Threde) ws pplied to mesure NH 3 concentrtions t three heights (,8 m, 1,85 m nd 3, m) t the downwind side of the field. This system delivered line concentrtions t time resolution of 2 min., further detils re described in Gärtner et l. (28). Emissions from the fertilized field were clculted by multiplying concentrtion nd wind profiles nd djusting geometriclly for the prt of the emissions pssing beyond the mesuring pth. 3. RESULTS AND DISCUSSION 3.1 Eddy covrince mesurements After the spreding of slurry, NH 3 concentrtions s recorded by etr-ms immeditely rose to more thn 1 ppm. Short term vritions between 1 ppb nd more thn 2 ppm were observed nd cler fluxes could be detected s reflected in the covrince functions (Fig. 1). The integrl dmping losses (dominted by tube effects) s determined by ogive nlysis were only bout 1% higher for NH 3 s compred to wter fluxes, suggesting tht the smpling nd mesurement setup ws successful. The emissions showed fst decrese with time tht could be described by n exponentil decy. E( t) t t F1 exp F2 exp 1 2 (Eq. 1) with two time constnts ( 1 nd 2 ) nd prmeters F 1 nd F 2 describing initil fluxes. Fig. 2 presents comprison of EC fluxes with those obtined by the erodynmic grdient, showing good greement. 3.2 Field Scle Emissions Due to the sequentil ppliction of the mnure (refilling of slurry tnks) nd the fst decrese of NH 3 voltiliztion, detiled footprint clcultions nd corrections with high temporl resolution were crucil for obtining representtive emission fluxes. Figure 3 illustrtes the sitution on the whet field indicting the loction of the EC sensors nd the six slurry trcks tht there were fertilized sequentilly (refilling of the tnks fter spreding).

3 For deriving the emission fluxes of the whole field, it ws ssumed tht the emissions of ech of the six trcks exhibited 1) the sme initil emission flux nd 2) the sme temporl decy. Next, the contribution of ech trck to the footprint of the EC mesurement ws clculted with n nlyticl footprint model (Kormnn nd Meixner, 21, Neftel et l., 28). At ny time, the flux s mesured by the EC system is thus given by F (Eq. 2) EC FPi Ei i with FP i being the footprint frctions (detils see Ammnn et l., 21) nd E i the emissions of ech trck. Using the mesured time series of fluxes nd the reltionships described by Eq.1 nd Eq.2 llowed finding best pproximtions for the constnts in Eq.1 nd thus deriving the integrl emissions of the whole field. Figure 4 shows both the emissions from individul trcks (dshed lines) nd the overll fluxes from the freshly fertilized field for the experiment on 4 th of August. Also shown re the overll emissions s obtined from mss blnce pproch using the open pth FTIR-mesurements. The good greement with this independent method supports the vlidity of the flux mesurement nd the footprint clcultions. A detiled evlution of this field intercomprison exercise will be given in forthcoming pper. 4. CONCLUSIONS An etr-ms system ws successfully pplied for EC mesurements of NH 3 emissions from griculturl fields following the ppliction of liquid cttle slurry. The key for chieving sufficiently fst time resolution ws heting both the inner surfces of the NH 3 instrument s well s the smpling line to t lest 15 C. The comprison of ll pplied methods showed good greement on the mgnitude of observed emission fluxes, confirming erlier mesurements t this field site being rther t the low end of emission fctors in the literture (15-2% losses of pplied nitrogen). ACKNOWLEDGEMENTS Funding for this work ws provided by the Swiss Federl Office for the Environment nd the Swiss Federl Office of Agriculture (project Vlidierung von Ammonikverlusten nch Ausbringung von Gülle uf Feldebene ), the EU project NitroEurope (IP) (contrct no ), the Swiss Ntionl Science Foundtion (project TERMS, /1) nd the Mrie Curie project CORN (PIEF-GA ). We thnk Andre Gärtner (Lndesmt für Ntur, Umwelt und Verbrucherschutz NRW, D Recklinghusen) nd Riner Hirschberger (Ingenieurgesellschft Niemnn & Prtner D Bochum) for providing the results of the Mss blnce pproch. REFERENCES Ammnn, C., Brunner, A., Spirig, C., nd Neftel, A.: Technicl Note: Wter vpour concentrtion nd flux mesurements with PTR-MS, Atmos. Chem. Phys., 6, , 26. Ammnn, C., Flechrd, C. R., Leifeld, J., Neftel, A., nd Fuhrer, J.: The crbon budget of newly estblished temperte grsslnd depends on mngement intensity, Agr. Ecosyst. Environ., doi:1.116/j.gee , 27. Ammnn, C., Spirig, C., Neftel, A: Vlidtion of simple footprint tool for trce gs flux mesurements bove griculturl fields. Proceedings of the 29th Conference on Agriculturl nd Forest Meteorology, Keystone CO, AMS, Boston. Flechrd, C. R., Spirig, C., Neftel, A., nd Ammnn, C.: The nnul mmoni budget of fertilised cut grsslnd Prt 2: Sesonl vritions nd compenstion point modeling, Biogeosciences, 7, , 21. Gertner, A., Hirschberger, R., nd Kotzin, F.: Estimtion of diffuse NH3 emissions during nd fter slurry spreding, Gefhrstoffe Reinhltung der Luft, 68, , 28. Génermont, S., nd Cellier, P.: A mechnistic model for estimting mmoni voltiliztion from slurry pplied to bre soil, Agr. Forest Meteorol., 88, , Pin, B. F., Phillips, V. R., Clrkson, C. R., nd Klrenbeek, J. V.: Loss of Nitrogen through Ammoni Voltiliztion During nd Following the Appliction of Pig or Cttle Slurry to Grsslnd, J. Sci. Food Agr., 47, 1-12, Misselbrook, T. H., Nicholson, F. A., nd Chmbers, B. J.: Predicting mmoni losses following the ppliction of livestock mnure to lnd, Bioresource Technology, 96, , 25.

4 Neftel A., Spirig C. nd Ammnn C., Appliction nd test of simple tool for opertionl footprint evlutions, Environmentl Pollution, 152, 3, , 28. Normn, M., Hnsel, A., nd Wisthler, A.: O2+ s regent ion in the PTR-MS instrument: Detection of gs-phse mmoni, Int. J. Mss Spectrom., 265, , 27. Normn, M., Spirig, C.,Wolff, V., Trebs, I., Flechrd, C.,Wisthler, A., Schnitzhofer, R., Hnsel, A., nd Neftel, A.: Intercomprison of mmoni mesurement techniques t n intensively mnged grsslnd site (Oensingen, Switzerlnd), Atmos. Chem. Phys., 9, , 29. Reidy, B., Rhimb, B., nd Menzi, H.: A new Swiss inventory of mmoni emissions from griculture bsed on survey on frm nd mnure mngement nd frm-specific model clcultions, Atmos. Environ., 42, , 28. Rochette, P., Guilmette, D., Chntigny, M. H., Angers, D. A., McDonld, J. D., Bertrnd, N., Prent, L. E., Cote, D., nd Gsser, M. O.: Ammoni voltiliztion following ppliction of pig slurry increses with slurry interception by grss folige, Cn. J. Soil Sci., 88, , 28. Sintermnn J., C. Spirig, A. Jordn, U. Kuhn, C. Ammnn nd A. Neftel, Eddy covrince flux mesurements of mmoni by mens of electron trnsfer rection mss spectrometry, to be submitted to Atmos. Mes. Tech. Diss., 21. Søgrd, H. T., Sommer, S. G., Hutchings, N. J., Huijsmns, J. F. M., Bussink, D. W., nd Nicholson, F.: Ammoni voltiliztion from field-pplied niml slurry - the ALFAM model, Atmos. Environ., 36, , 22. Spirig, C., Neftel, A., Ammnn, C., Dommen, J., Grbmer, W., Thielmnn, A., Schub, A., Beuchmp, J., Wisthler, A., nd Hnsel, A.: Eddy covrince flux mesurements of biogenic VOCs during ECHO 23 using proton trnsfer rection mss spectrometry, Atmos. Chem. Phys, 5, , 25. Spirig, C., Flechrd, C.R., Ammnn, C., nd Neftel, A.: The nnul mmoni budget of fertilised cut grsslnd Prt 1: Micrometeorologicl flux mesurements nd emissions fter slurry ppliction, Biogeosciences, 7, , 21. Figures.12 5.e+4 5.e+4 w't'.12 w'nh 3 ' 4.e+4 4.e+4 8 w'h 2 O' 8 w't' [ C ms -1 ] w't' [ C ms -1 ] w'nh 3 ' [ng m -2 s -1 ] 3.e+4 2.e+4 1.e+4-1.e+4 3.e+4 2.e+4 1.e+4-1.e+4-2.e+4-2.e+4 w'nh 3 ' [ng m -2 s -1 ] w'nh 3 ' [mmol mol -1 ms -1 ] dely time [s] dely time [s] dely time [s] Fig. 1: Covrince functions of verticl wind speed with temperture, mmoni nd wter vpor w'h 2 O' [mmol mol -1 ms -1 ]

5 p ( ) 12 EC - ETRMS 2 EC - ETRMS 1 AGM cont 16 AGM cont NH 3 flux [ng m -2 s -1 ] : : : : : : : : : : : dte, time [MEZ] dte, time [CET] Fig. 2: Comprison of mmoni fluxes s mesured by eddy covrince nd erodynmic grdient methods Fig. 3: Appliction of liquid cttle slurry on Aug-4 by sequentil spreding of six tnks (trcks # 1-6) nd position of EC system (cross). 15' Eddy Covrince Mesurements, 4 Aug ' Eddy Covrince Mesurements, 4 Aug surfce emission (fitted) for trck #1...#6 vg. emission of entire field (ll trcks) vg. emission of entire field (ll trcks) mss blnce method ] -1 s 1' -2 m g [n x flu H 3 5' N fertilized re 1..5 ] [h re d e rtiliz fe ] -1 s 1' -2 m g [n x f lu H 3 5' N fertilized re 1..5 ] [h re d e rtiliz fe 12: 13: 14: 15: 16: 17: 18: 19: 2: time of the dy [CET] (mid intervl) 12: 13: 14: 15: 16: 17: 18: 19: 2: time of the dy [CET] (mid intervl) Fig. 4: Determintion of the overll fluxes of the entire field; emissions of individul slurry trcks (left) nd comprison to open pth FTIR-results (right).