N and P balances in Denmark 1985-2005 on national and regional scale Finn P. Vinther and Arne Kyllingsbæk   UNIVERSITY OF AARHUS Faculty of Agricultural Sciences Dept. of Agroecology and Environment Blichers Allé 20, P.O. BOX 50 DK-8830 Tjele Former; Danish Institute of Agricultural Sciences (DIAS)

Danish Institute of Agricultural Sciences Foulum Faculty of Agricultural Sciences Flakkebjerg Årslev

Inst. of Agroecology and Environment

Methodology The balances have been calculated according to methodologies described in the OECD/EUROSTAT handbooks on Gross Nitrogen Balances (Dec. 2003) and Phosphorus Balances (March 2004), respectively.

Input: Inorganic fertilisers: Directly from Statistics Denmark. Organic fertilisers (excl. livestock manure): The amount of sewage sludge and industrial waste products is estimated based on data from Danish Environmental Protection Agency along with information on content of N and P. Livestock manure: Number of animals in the OECD categories is provided by Statistics Denmark. Manure coefficients (ex animal) for each animal category [kg N and P/head/year] are each year updated by Inst. of Animal Health, Welfare and Nutrition, University of Aarhus. N2 fixation by grass-clover and legumes: Area with leguminous crops is provided by Statistics Denmark and N2 fixation coefficients for a given crop [kg N/ha] are estimated using an empirical model Høgh-Jensen et al. (2003, 2004). Atmospheric deposition: Based on annual estimates from NERI Seeds: Amount from Statistics Denmark and concentrations of N and P are obtained from a ‘Feed stuff’ database providing this information for a large number of feed stuff and crops. The database is updated at regular intervals (latest 2005). Cereals are analysed for N and P content annually.

Output: Harvested and fodder crops: Area and yield of various crops, such as cereals, oil seed crops and fodder crops are obtained from Statistics Denmark and concentrations of N and P are obtained from the ‘Feed stuff’ database; see above.

Balance: Field balance (National level) Field N surplus: Volatilisation Field balance (National level) Field N surplus: - NH3 volatilisation Standard coefficients - Denitrification An empirical model SIMDEN = N leaching

Results 1985 - 2005

Results 1985 - 2005 Total Dairy cows Cattle Pigs Total Fattening pigs

Nitrogen input Total Fertilisers Animal manure N2 fixation, deposition and seed

Crop yields

Crop yields - 0.8 kg N/ha/year

Nitrogen Use Efficiency 0.6 % per year

N surplus - 4 kg N/ha/year

Improvements in NUE resulting in reduced N surplus are primarily the result of legislations concerning: Maximum limits on application of fertilisers for individual crops Statutory norms for the proportion of manure N assumed to be plant available, e.g. pig slurry 70% Obligatory fertiliser plans

Phosphorus Total Animal manure Fertilisers Deposition and seed

Regional balances ?

Administrative units Communes

Administrative units Counties Units at Statistics Denmark until 2007

Administrative units Regions

Units at Statistics Denmark from 2007

Thank you for your attention !!!

N2 fixation: N2 fixation (kg N/ha) = Høgh-Jensen, H., Loges, R., Jensen, E.S., Jørgensen, F.V. & Vinther, F.P. (1998) Empirisk model til kvantificering af symbiotisk kvælstoffiksering i bælgplanter. I Kristensen, E.S. & Olesen, J.E. (eds.) Kvælstofudvaskning og -balancer i konventionelle og økologiske produktionssystemer. FØJO-rapport nr. 2, 69-82. Høgh-Jensen, H., Loges, R., Jørgensen, F.V., Jensen, E.S. and Vinther, F. P. (2004) An empirical model for quantification of symbiotic nitrogen fixation in grass-clover mixtures. Agricultural Systems 82, 181-194. N2 fixation (kg N/ha) = Harvested legume DM (kg/ha) * N% * Pfix * (1 + Proot+stuble + Ptrans-soil + Ptrans-animal + Pimmobil)

Denitrification & N2O emission: Vinther, F. P. and Hansen, S. (2004) SIMDEN – a simple model for quantification of N2O emission and denitrification. DJF report 104, 1-47 (In Danish) Input variables: Amount of N applied Clay content of the soil SIMDEN

SimDen compared to measured values: Danish measurements

Spain (Vallejo et al., 2004)

The Netherlands (Zwart et al., 2004)