N surplus and handling of WFD in the Netherlands

Gerard Velthof

Outline of presentation

WFD in the Netherlands

Soil types, groundwater levels and land use

Legislation

Studies on clay and peat sites

Conclusions

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

Current standards for water quality in the Netherlands

Groundwater: 50 mg NO3 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)

Legislation in the Netherlands: fertiliser act Loss standards (surplus): MINAS (1998 –

2005)

Application standards: from 1st January 2006

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

N and P surplus of agriculture in NL

Fraters et al., 2005

Nitrate concentration groundwater

Fraters et al., 2005

Fraters et al., 2005

Fraters et al., 2005

Fraters et al., 2005

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

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

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

Methodology to underpin N application rates Relation between N surplus and NO3-

concentration [NO3] = N surplus x leaching fraction/precipitation surplus

NO3 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)

Leaching fractions

0

20

40

60

80

100

120

Clay Sand Sand Sand Peat Clay Sand Sand Sand

leaching fraction, % N surplus

grasslandarable land

wet dryintermediate wet dryintermediate

Schröder et al. (2004 & 2005)

Input Manure 275 275Fertiliser 171 171Deposition 31 31Mineral N in spring 30Crop residue t= -1 yr 121Manure t = -1 yr 69TOTAL 697

Output Harvest 324 324Ammonia volatilisation 19 19

Mineral N end winter 30Crop residue t =+1 yr 121Manure t= +1 yr 69TOTAL 563

N surplus 134 134Leaching fraction, % 28Precipitation Surplus, mm 329

NO3 concentration, mg N/l 11,3

An example

Schröder et al. (2005)

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

N budget of grassland on a clay soil, kg N ha-1 yr-1

    2003 2004

Input Slurry (after NH3 emission) 321 206

Fertilizer 139 189

Grazing 44 21

Deposition 34 34

Output Uptake cattle 96 32

Cutting 285 388

Drainage; trenches 4 19

Drainage; tile drains 2 7

Leaching groundwater 0 0

  Denitrification 127 143

Input - Output 24 -139

Van der Salm et al. (submitted)

Composition of drainage water; clay soil

Van der Salm et al., unpublished

0

2

4

6

8

10

12

27 N

ov

3 Dec

17 D

ec

22 D

ec

29 D

ec5

Jan

12 J

an

19 J

an

26 J

an

2 Feb

9 Feb

16 F

eb

23 F

eb

23 M

arch

29 M

arch

organic N

NO3

NH4

To

tal n

itro

ge

n,

mg

N L

-1

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

Quality of ditch water in peat areas

Total N and P concentration frequently exceeds standard of 2.2 mg N l-1

NO3: < 1 mg N l-1

NH4 and organic N up to 20 mg N l-1

Contribution of N sources to loading of ditch

0%

25%

50%

75%

100%

Winter season Summer season

Peat mineralisation

Fertilizers and manures

Inlet water

Atmospheric deposition

Van der Beek et al., 2004

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

Additional measures required?

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

© Wageningen UR

Thank you!

MINAS: allowable nitrogen surplus (kg N per ha)  Grassland Arable land

  All Clay/peat Sand/loess

1998-1999 300 175 175

2000 275 150 150

2001 250 150 125

2002-2005 220/190 150 110/100

Examples of N application standards in 2009Crop N rate, kg available N ha-1 yr-1

Sand Clay

Mown grassland 340 350

Grazed grassland

260 310

Potato ….. 250

Sugar beet ….. 220

Maize 150 160

Wheat …… 220