1. N surplus and handling of WFD in the Netherlands Gerard Velthof

2. Outline of presentation WFD in the Netherlands Soil types, groundwater levels and land use Legislation Studies on clay and peat sites Conclusions

3. Water Framework Directive in the Netherlands Four river basins: Rhine, Meuse, Scheldt and Ems Targets and measures are set in 2009 2015: good ecological condition achieved N and P application according to action plan Nitrate Directive

4. Current standards for water quality in the Netherlands Groundwater: 50 mg NO 3 per liter Surface waters (sensitive for eutrophication): 2.2 mg total N per liter (in summer) 0.15 mg total P per liter (in summer)

5. Legislation in the Netherlands: fertiliser act Loss standards (surplus): MINAS (1998 – 2005) Application standards: from 1st January 2006

6. MINAS: N and P balance on farm scale Inputs: fertilizer, manure, feed, …. Outputs: crops, milk, meat, eggs, manure …. Surplus should be less than an allowable surplus levies when surplus exceeded allowable surplus

7. N and P surplus of agriculture in NL Fraters et al., 2005

8. Nitrate concentration groundwater Fraters et al., 2005

12. Conclusions MINAS (1998 – 2005) Decrease in N and P surplus Decrease in nitrate concentration groundwater Decrease in total N concentration surface water No effect on P concentration surface water

13. European Court (October 2003) Shortcomings MINAS: evaluation of past season instead of required planning of next season poorly documented default values and missing terms high allowable surpluses levies not prohibitive In 2006 nutrient application standards introduced

14. Three types application standards N fertilizer recommendation except when nitrate concentration is exceeded Animal manure 170 kg N per ha, except for dairy farming systems (derogation of 250 kg N per ha) Phosphorus: in 2015 equilibrium

15. Methodology to underpin N application rates Relation between N surplus and NO 3 - concentration [NO 3 ] = N surplus x leaching fraction/precipitation surplus NO 3 leaching fraction = f (soil type, crop type) Relation between N-input, N-output, N-surplus Inputs: fertiliser, manure, deposition, residues, … Outputs: volatilisation, harvest, residues, …. Harvest: available N, recovery and harvest index Schröder et al. (2004 & 2005)

16. Leaching fractions Schröder et al. (2004 & 2005)

17. InputManure 275 Fertiliser 171 Deposition 31 Mineral N in spring 30 Crop residue t= -1 yr 121 Manure t = -1 yr 69 TOTAL 697 OutputHarvest 324 Ammonia volatilisation 19 Mineral N end winter 30 Crop residue t =+1 yr 121 Manure t= +1 yr 69 TOTAL 563 N surplus 134 Leaching fraction, % 28 Precipitation Surplus, mm 329 NO 3 concentration, mg N/l 11,3 An example Schröder et al. (2005)

18. Experiment on a heavy clay Field balances of nitrogen and phosphorus Two years monitoring: Denitrification (acetylene inhibition) Leaching of N and P to surface water: Trenches Tile drains

19. N budget of grassland on a clay soil, kg N ha -1 yr -1 20032004 InputSlurry (after NH 3 emission)321206 Fertilizer139189 Grazing4421 Deposition34 OutputUptake cattle9632 Cutting285388 Drainage; trenches 419 Drainage; tile drains27 Leaching groundwater00 Denitrification127143 Input - Output24-139 Van der Salm et al. (submitted)

20. Composition of drainage water; clay soil Van der Salm et al., unpublished 0 2 4 6 8 10 12 27 Nov 3 Dec 17 Dec22 Dec29 Dec 5 Jan 12 Jan19 Jan26 Jan 2 Feb9 Feb 16 Feb23 Feb 23 March29 March organic N NO 3 NH 4 Total nitrogen, mg N L -1

21. Grassland on peat soils Drained peat soils frequently used as managed grassland Nitrogen input via fertilizer and manure High mineralisation of peat High groundwater levels High density of ditches

22. Quality of ditch water in peat areas Total N and P concentration frequently exceeds standard of 2.2 mg N l -1 NO 3 : < 1 mg N l -1 NH 4 and organic N up to 20 mg N l -1

23. Contribution of N sources to loading of ditch Van der Beek et al., 2004

24. Conclusions N concentration in ground and surface waters decrease No changes in P concentration in surface water Standards sufficient to meet the targets of the WFD? Targets in WFD not yet set P leaching important Role of soluble organic N? Other sources Peak events: surface run-off Respons time

25. Additional measures required? Timing of manure and fertilizer application Bufferstrips near surface waters Hydrological measures Cleaning of ditches Negative surplus for P: mining

26. © Wageningen UR Thank you!

27. MINAS: allowable nitrogen surplus (kg N per ha) GrasslandArable land AllClay/peatSand/loess 1998-1999300175 2000275150 2001250150125 2002-2005220/190150110/100

28. Examples of N application standards in 2009 CropN rate, kg available N ha -1 yr -1 SandClay Mown grassland340350 Grazed grassland260310 Potato…..250 Sugar beet…..220 Maize150160 Wheat……220