Assessment of agricultural nitrogen balances for municipalities – Example Baden-Wuerttemberg martin.bach@agrar.uni-giessen.de EEA Agri-water Expert meeting,

Präsentation zum Thema: "Assessment of agricultural nitrogen balances for municipalities – Example Baden-Wuerttemberg martin.bach@agrar.uni-giessen.de EEA Agri-water Expert meeting,"—  Präsentation transkript:

1 Assessment of agricultural nitrogen balances for municipalities – Example Baden-Wuerttemberg
EEA Agri-water Expert meeting, Copenhagen, Feb 2005

2 Usage of ‚nitrogen balance surplus‘
EU, OECD: Agri-sustainability indicator environmental pressures (water, atmosphere) waste of resources  Effectiveness of policies: EU Nitrate Directive, national action programmes  Verification of supra-national treaties, e.g. OSPARCOM  Sustainability Strategy Program of the German Gouvernment: DUX-Indicator (‚German Environment Index‘) „Trend of the national nitrogen surplus“  Component of „National Gross Environmental Budget“ (UGR, Umwelt ökonomische Gesamtrechnung), indicating the external costs of nitrogen losses into air, terrestrial ecosystems, surface waters, groundwater, sea  WFD implementation: source appointment, prediction of efficiency of reduction measures  Farm level: Optimization of N-management (tools e.g.: EMA in the UK; REPRO, QSL in Germany)

3 Nitrogen soil surface surplus in the WFD context
„Best available indicator“ for water quality eutrophication by non-point source N losses e.g. Modelling approaches of EUROHARP models, especially MONERIS WFD: ‚10 km² basin units‘  spatially differentiated calculation of N surplus max resolution of ag-census based N balance Germany: municipalities (EU LAU level 2)

4 Ag-census based calculation of nitrogen soil surface surplus
Problems  Lack of data (data secrecy)  Estimation of N mineral fertilizing quantities

5 Missing data of the Agricultural Census
Background Data secrecy policy: a statistical data won‘t be published when based on three or less individual values Replacement by estimated figures: missing data recalculted as the difference between „sum over a county“ and „sum over all muncipalities with published data“

6 Fraction of municipalities* Missing quantity % of state total
Missing data of the Agricultural Census - Crop acreage Crop (acreage) No. of missing data Fraction of municipalities* Missing quantity % of state total Agricultural land total 9 0,8 % 0,1 % Arable land 31 1,4 % Pasture 16 26,6 % Orchards 295 n.d. 2,3 % Vineyards 2,9 % Wheat 53 4,8 % Barley 117 10,5 % 0,7 % Legumes 326 29,3 % 12,6 % Potatoes 139 12,5 % 1,9 % Sugar beet 143 12,9 % 4,0 % Fodder maise 163 14,7 % 1,7% Oilseed rape 232 20,9 % 2,8 % Vegetable 340 30,6 % 12,1 % *) n = 1112 municipalities

7 Fraction of municipalities* Missing quantity % of state total
Missing data of the Agricultural Census - Livestock Livestock (heads) No. of missing data Fraction of municipalities* Missing quantity % of state total Bovines total 113 10,2 % 0,6 % - therefore cows 172 15,5 % 1,4 % Pigs total 235 21,2 % 2,4 % - therefore souws 339 30,5 % 7,6 % Sheep 442 39,8 % 32,1 % Poltry 284 25,6 % 42,1 % *) n = 1112 municipalities

8 Estimation approch of nitrogen mineral fertilization
„farmer‘s N fertilization scheme“: N plant demand = N mineral fertilization + N organic fertilizer*efficiency factor + other N supply N plant demand: crop specific N demand for optimal harvest yield (table values) N organic fertilizing: N supply to the field with farm produced manure; N supply = N excretion of livestock minus volatilzation losses Efficiency factor: fraction of N in manure which is availabe for the field crop, according to farmers fertilization calculation Other N supply: N-fixation by legumes, secondary organic fertilizers N mineral fertilization = N plant demand – N organic fertilizer*efficiency factor – other N supply

9 Estimation approach of nitrogen mineral fertilization
„Validation“ of the assessment: Estimated N mineral fertilizer amounts summed up over all crops and all counties in Germany  mineral fertilizer consumption of agriculture in total (census based) Best calibration with an efficiency factor = 36 % (average Germany 1998/2000).  Farmers do not accounted for 64 % of N in their manure (= potential losses when planning crop fertilization schemes) Figures (kg N/ha AA, average Germany 1998/2000): plant demand – organic fertilizer*efficiency factor – other supply = mineral fertilizer – * , – =  used for calculation of mineral fertilizing of individual municipalities

10 Nitrogen surplus Results for Municipalities* Baden-Wuerttemberg 1999
Nitrogen soil surface surplus kg N/ha AA Nitrogen surplus Results for Municipalities* Baden-Wuerttemberg 1999 *) EU LAU level 2, NUTS 5 no agriculture no data Lake Contance

11 Quality check of nitrogen soil surface surplus results
40 80 120 160 200 1 : 1-Line r² = 0,45 Comparison of Ag-Census based vs. empirical N budgets (mainly farm based data) Database: Literature review, 8 studies with together 32 municipalities (in 5 German states) (Bach et al.,1996) Nitrogen surplus based on Agricultural Census (kg N/ha AA) Nitrogen surplus acc. to empirical data (kg N/ha AA)

12 Groundwater NO3-concentration measurement / model (%)
Baden-Wuerttemberg: NO3-conc. in aquifers measured vs. modelled Groundwater NO3-concentration Relation measurement / model (%) <= 40 % % % % % > 150 % Source: J. Ruf, Environment Agency Baden-Wuerttemberg, 2004

13 Resume  Assessment of nitrogen balances for municipalities yields reasonable, quantitative figures with high spatially resolution  Results are an operational tool for the WFD status reports (‚at risk‘ vs. ‘not at risk‘; source apportionment) But: Farm-gate balances are methodologically more precise and the results indicate the problem closer to its origin (farms with huge livestock density) Outlook: Prediction of effectiveness (and efficiency) of nitrogen loss reduction measures in ag production systems needs process oriented nitrogen models (e.g. SWAT, DNDC and others) ‚nitrogen surplus‘ is not sufficient for this purpose.

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15 Thank you for your attention! You are a great audience!

16 Source: Landesanstalt fuer Umwelt- schutz Baden-Württemberg, 2000
MONERIS (Behrendt et al., 1999) Results Baden-Wuerttemberg Total Nitrogen emissions from: • Groundwater • Tile drainage • Erosion • Surface runoff • WWTP • Urbans areas • Atmospheric deposition Source: Landesanstalt fuer Umwelt- schutz Baden-Württemberg, 2000

17 National (farm-gate) balance Soil surface (crop production) balance
Nitrogen balance of German agriculture 2000 Balance Position National (farm-gate) balance Soil surface (crop production) balance kg N/hectare AA Mineral (chemical) fertilizier +109 Secondary organic fertilizer (sewage sludge, compost) + 4 Imported fodder + 22 Fodder from domestic processing + 14 Organic fertilizing (manure) + 50 Atmospheric deposition (netto) NH3-deposition on ag area + 10 + 12 Legume nitrogen fixation + 11 Market export of crop products - 35 Market export of livestock products - 19 Harvest withdrawal -121 Balance surplus = 117 = 75

18 Bsp. Hessen: Auswertung WSG
WSG-Zonen Zone I Zone II Zone III Zone IIIA Zone IIIB Wasserschutz- gebietszonen Landnutzung N-Saldo Hydrogeolog. Einheiten Boden (NAG), Niederschlag

19 Schätzung NO3-Konz. in GW-Messstellen Regressionsansatz
log (CNO3) = a0 + a1*Wald% + a2*Siedl% + a3*Grünl% + a4*(Acker%*N-Saldo) + a5*Tiefe + a6*SWS CNO = Mittlere Nitratkonz. des Rohwassers (mg NO3/l) Wald% = Anteil des Waldes an der Gesamtfläche (%) Grünl% = Anteil des Grünlands an der Gesamtfläche (%) Siedl% = Anteil der Siedlung an der Gesamtfläche (%) Acker%*N-Saldo = Produkt aus Ackerlandanteil und mittlerem N-Bilanzüberschuss Tiefe = Mittlere Rohwasserentnahmetiefe (m) SWS = Geschätzte mittlere Sickerwasserspende (mm/a)

20 NO3-Konz. (mg/l) (gemessen)
Bsp. Hessen: Regressionsgleichung - Brunnen Alle Brunnen-Messstellen (Hessen gesamt), n = 811 log (CNO3) = 1,964 – 7,04E-03*Wald% – 4,15E-03*Grünl% – 2,43E-03*Tiefe – 6,19E-04*SWS 100 Modellschritt r2 Korrigiertes r2 1. Wald% ,259 ,258 2. Grünl% ,341 ,339 3. Tiefe ,397 ,395 4. SWS ,418 ,415 75 NO3-Konz. (mg/l) (gemessen) 50 25 25 50 75 100 NO3-Konz. (mg/l) (berechnet)

21 NO3-Konz. (mg/l) (gemessen)
Bsp. Hessen: Regressionsgleichung - Quellen (‚SQS‘) Einheit: Nordhessisches Buntsandsteingebiet , n = 82 log (CNO3) = 1,889 – 8,57E-03*Wald% – 5,97E-04*SWS SQS r2 Korrigiertes r2 Wald% ,697 ,694 SWS ,716 ,709 NO3-Konz. (mg/l) (gemessen) NO3-Konz. (mg/l) (berechnet)

22 Bsp. Hessen: Ergebnisse (r²)
Hydrogeologische Großeinheiten Brunnen Quellen (SQS) n r2 Hessen gesamt 811 ,415 1057 ,406 Nordhessisches Buntsandsteingebiet 91 ,569 82 ,709 Niederh. Senke und Röt-Muschelkalk 25 ,607 43 ,469 Rheinisches Schiefergebirge 211 ,329 276 ,474 Basaltgebiete 138 ,358 83 ,367 Osthessisches Buntsandstein-Gebiet 192 ,424 228 ,552 Quartär und Tertiär des Untermain 49 ,327 7 n.s. Kristallin und Rotliegendes 71 ,274 238 ,280 Quartär des Oberrheingrabens 12 20 Buntsandstein-Gebiet des Odenwaldes 22 ,560 80 ,423

23 Quelle: J. Ruf, LfU Baden-Württemberg, 2003
Bsp. Baden-Württemberg: Berechnete Denitrifikationsraten Modellberechnung* Messung Grundwasserleiter Kluftgrundwasser Karst Sonstige *) Denitrifikationsrate = f{N-Überschuss LF, N-Deposition Wald, Nutzungsanteile, Sickerwassermenge, c(NO3)-GW gemess. } Quelle: J. Ruf, LfU Baden-Württemberg, 2003

24 Nitrogen surplus (kg N/ha AA) National balance („farm gate“)
Nitrogen balance surplus Germany 1950 to 2002* 50 100 150 1950 1960 1970 1980 1990 2000 50 100 150 Nitrogen surplus (kg N/ha AA) National balance („farm gate“) Soil surface balance *) 2002: preliminary results

25 Nitrogen Surplus - Soil surface balance -
of the Agricultural Area (AA) 1999 - Germany, NUTS 3 level (counties) - kg N / hectare AA

26 Nitrogen Surplus related to the total land area of the counties (all land uses*) 1999 - Germany, NUTS 3 level (counties) - kg N / hectare total area *) AA: N soil surface surplus of the agricultural land; other uses (forest; urban and traffic areas): 5 kg N/ha N surplus

27 Überschuss Stickstoff-Flächenbilanz
N-Bilanzüberschuss Baden-Württemberg MONERIS Ergebnisse (Behrendt et al.) Überschuss Stickstoff-Flächenbilanz <= 70 kg kg N/ha 71 – kg N/ha 81 – kg N/ha 91 – 100 kg N/ha 101 – 110 kg N/ha 111 – 120 kg N/ha 121 – 130 kg N/ha >130 kg N/ha Quelle: Landesanstalt für Umwelt- schutz Baden-Württemberg, 2000

28 Nährstoffbilanzierung Baden-Württemberg - MONERIS Baden-Württemberg -
Stickstoff-Flächenbilanzüberschuss Landwirtschaft (Bach / 1995) Stickstoff-Hoftorbilanzüberschuss Landwirtschaft (Zeddies / 2001) Quelle: LfU – Landesanstalt für Umweltschutz Baden-Württemberg – Sachgeb. 41.1

29 Nährstoffbilanzierung Baden-Württemberg - MONERIS Baden-Württemberg -
Gesamte spezifische Stickstoff-Emissionen nach MONERIS: • Grundwasser • Drainagen • Erosion • Abschwemmung • Kläranlagen • Urbane Flächen • Atmosphär. Deposition Quelle: LfU – Landesanstalt für Umweltschutz Baden-Württemberg– Sachgeb. 41.1

30 Überschuss der Stickstoff- Flächenbilanz der Gemeinden in Hessen 1999
kg N / ha LF Bach und Frede (2002)

31 Usage of ‚nitrogen balance surplus‘
EU, OECD: Agri-sustainability indicator environmental pressures (water, atmosphere) waste of resources  Effectiveness of policies: EU Nitrate Directive, national action programmes  Verification of supra-national treaties, e.g. OSPARCOM  Sustainability Strategy Program of the German Gouvernment: DUX-Indicator (‚German Environment Index‘) „Trend of the national nitrogen surplus“  Component of „National Gross Environmental Budget“ (UGR, Umwelt ökonomische Gesamtrechnung), indicating the external costs of nitrogen losses into air, terrestrial ecosystems, surface waters, groundwater, sea  WFD implementation: source appointment, prediction of efficiency of reduction measures  Farm level: Optimization of N-management (tools e.g.: EMA in the UK; REPRO, QSL in Germany)