Assessment of agricultural nitrogen balances for municipalities – Example Baden-Wuerttemberg martin.bach@agrar.uni-giessen.de EEA Agri-water Expert meeting, Copenhagen, 21-22 Feb 2005

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)

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)

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

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“

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

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

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

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 144 – 53 * 0,36 – 15 = 110  used for calculation of mineral fertilizing of individual municipalities

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

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)

Groundwater NO3-concentration measurement / model (%) Baden-Wuerttemberg: NO3-conc. in aquifers measured vs. modelled Groundwater NO3-concentration Relation measurement / model (%) <= 40 % 41 - 60 % 61 - 80 % 81 - 125 % 126 - 150 % > 150 % Source: J. Ruf, Environment Agency Baden-Wuerttemberg, 2004

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.

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

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

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

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

Schätzung NO3-Konz. in GW-Messstellen Regressionsansatz log (CNO3) = a0 + a1*Wald% + a2*Siedl% + a3*Grünl% + a4*(Acker%*N-Saldo) + a5*Tiefe + a6*SWS CNO3 = 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)

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)

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)

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

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

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

Nitrogen Surplus - Soil surface balance - of the Agricultural Area (AA) 1999 - Germany, NUTS 3 level (counties) - kg N / hectare AA 21 - 50 51 - 80 81 - 110 111 - 150 151 - 200 201 - 260

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 5 - 20 21 - 50 51 - 80 81 - 110 111 - 150 151 - 200 201 - 210 *) AA: N soil surface surplus of the agricultural land; other uses (forest; urban and traffic areas): 5 kg N/ha N surplus

Überschuss Stickstoff-Flächenbilanz N-Bilanzüberschuss Baden-Württemberg MONERIS Ergebnisse (Behrendt et al.) Überschuss Stickstoff-Flächenbilanz <= 70 kg kg N/ha 71 – 80 kg N/ha 81 – 90 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

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

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

Überschuss der Stickstoff- Flächenbilanz der Gemeinden in Hessen 1999 kg N / ha LF 20 - 40 41 - 60 61 - 80 81 - 100 101 - 115 115 - 130 Bach und Frede (2002)

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)