gross nutrient balances: german experiences volker appel, bmelv-425 working party "agriculture...
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WP Agriculture and environment, Dec, Calculation of regional nutrient balances The following results come from …. SCANUBA = Scale dependent nutrient balances German TAPAS 2007 action on calculating regional soil surface N balances (Julius Kühn-Institute / University of Gießen, 2008)TRANSCRIPT
Gross nutrient balances: German experiences
Volker Appel, BMELV-425
WORKING PARTY "AGRICULTURE AND ENVIRONMENT"
OF THE STANDING COMMITTEE FOR AGRICULTURAL STATISTICS
WP Agriculture and environment, 11-12 Dec, 2008
2
IntroductionNutrient use in agriculture high importance for understanding interactions between agriculture and environment
Plant production requires an adequate supply of nutrients in the soil↨
Concerns about the environmental effects of nutrient surpluses (NO3
- in ground water, emission of trace gases, P concentrations in surface waters)
Nitrogen balance = indicator in National Sustainability Strategy
WP Agriculture and environment, 11-12 Dec, 2008
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Calculation of regional nutrient balances
The following results come from ….SCANUBA = Scale dependent nutrient balancesGerman TAPAS 2007 action on calculating regional soil surface N balances(Julius Kühn-Institute / University of Gießen, 2008)
WP Agriculture and environment, 11-12 Dec, 2008
4
Input and output variables of the national German N balance average 2000 - 2005
NITROGEN INPUTS [%]
Mineral fertilisers
Organic fertilisers
Livestock manure
Atmospheric deposition
Biological nitrogen fixation
Seeds and planting material
NITROGEN OUTPUTS [%]
Cereals
Oil cropsLegumes
Industrial cropsOther crops
Harvested fodder crops
Pasture
WP Agriculture and environment, 11-12 Dec, 2008
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Assumptions1. Nitrogen pool in the soil will remain unchanged.
2. Nitrogen losses by soil erosion / nitrogen enrichment due to sedimented material are unaccounted for.
3. Gaseous NO und N2 emissions from nitrification and denitrification processes in soils are not included in the balance.
4. Non biotic nitrogen fixation from the atmosphere will not be considered.
WP Agriculture and environment, 11-12 Dec, 2008
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Data sources1. land use data, yield/ha, livestock numbers: agricultural
statistics
2. milk yield, regional share of different animal housing systems, volatilised NH3 and N2O: National Inventory Report 2006
3. nitrogen input by deposition : „National implementation of the UNECE Convention on Long-range Transboundary Air Pollution“ 2007
4. N-coefficients: Ordinance on Fertilisation (Düngeverordnung) and publications by Association for Technology and Structures in Agriculture (KTBL)
WP Agriculture and environment, 11-12 Dec, 2008
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Computation procedure I
Data on mineral fertilizer: reliable only at national level (and for large NUTS 1 regions) 1st step:
calculation of Total N demand of crops at NUTS 3 = f (acreage, yield)
2nd step:
Mineral N fertilisation =Total N demand of crops - livestock manure*deduction factor - organic fertilizer - legume N fixation(Assumption: farmers account for 100 % of N supplied, except livestock manure)
WP Agriculture and environment, 11-12 Dec, 2008
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Computation procedure II
3rd step:
Compute deduction factor at national level, solving the last equation in reverse direction ↔ values between 0.15 and 0.4 (for different years)
4th step:
Insert deduction factor into above equation to compute mineral fertilzer quantities at NUTS 3 level
5th step:
Insert these data into the nitrogen balance
WP Agriculture and environment, 11-12 Dec, 2008
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Gross N balance 2003 Net N balance 2003
WP Agriculture and environment, 11-12 Dec, 2008
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Problems within this approachData gaps relevant at regional level:• mineral fertiliser • imports / exports of livestock manure• organic secondary raw material• yield of several field crops and permanent crops
Assumption of optimal (100 %) use of mineral fertiliser transfer of environmental problems to livestock manure.
Uniform deduction factor for livestock manure!
WP Agriculture and environment, 11-12 Dec, 2008
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Possible ways forwardImprove quality and remove uncertainties of single elements of the balance equation:• site conditions ↔ N demand of crops• check „top-down-approach“ with „bottom-up-approach“ using farm accountancy data → derive input/output coefficients and transfer functions (OSTERBURG/SCHMIDT/GAY, 2004; OSTERBURG/SCHMIDT, 2008)_______________________________________
Keep in mind: cost-benefit-ratio!
WP Agriculture and environment, 11-12 Dec, 2008
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N balance surplus for Germany sector balance, kg/ha UAA (3 year moving average)
Source: Destatis, Sustainable Development in Germany - Indicator Report 2008 for the National Sustainability Strategy