The Netherlands. Nitrate problem in the Netherlands. Compare California and the Netherlands

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1 The Netherlands National Institute for Public Health and the Environment Dico Fraters and Leo Boumans (RIVM) Joan Reijs and Ton van Leeuwen (LEI) Relationship between surplus and nitrate on sandy soils - Temperate marine climate - West: Holocene river and marine deposits - East: Pleistocene wind deposits Nitrogen surplus and nitrate 2 Compare California and the Netherlands Intensive agriculture in NL Compare California The Netherlands Area (1 km 2 ) Population (million) Agricultural land (million ha) 1 2 Cattle (million heads) Dairy cows Pigs (million heads).2 12 Nitrate problem in the Netherlands Exceedance of EU nitrate target value in root zone leachate Region >5 mg NO 3 /l Sand 65% Loess 85% Clay 3% Peat < 5% statistical model using monitoring data nitrate (mg/l) not relevant or no data > 15 Nitrogen surplus and nitrate Nitrogen surplus and nitrate 4 Nitrogen surplus to high? soil root zone balance [1] Nitrogen surplus to high? soil root zone balance [2] Application of Fertiliser &M Manure NH 4 emission N fixation Plant uptake Application of Fertiliser &M Manure NH 4 emission N fixation Plant uptake Atmospheric N deposition Atmospheric N deposition Root zone Nitrogen surplus and nitrate 5 Soil N+P Mineralization Fixation Root zone Nitrogen surplus and nitrate 6

2 Destiny of surplus Problem definition and solution N2, NO2 Root zone Problem How much can be applied without exceeding the EU nitrate target value (5 mg/l) Denitrification NO3 Unsaturated zone Upper meter of groundwater Solution: black box empirical model Use existing data to derive relationships between N fertilization and (agricultural research) and (trend monitoring network) and nitrate concentration (environmental research) Nitrogen surplus and nitrate 7 Nitrogen surplus and nitrate 8 Deriving fertilization standards Deriving a (NLF) Farm N Fertilization input / output i standard d Field N input / output Farm Accountancy Field N input / output Data Model A2 Model A2 Model B2 Model B2 Nitrate target value Field measurement Nitrogen surplus and nitrate 9 Nitrogen surplus and nitrate 1 Relation between and Deriving a (NLF) Use of data from Mineral Policy Monitoring Programme = Nitrogen surplus and nitrate 11 Nitrogen surplus and nitrate 12

3 Minerals Policy Monitoring Programme Sand region of the Netherlands 1. Monitoring water quality 2. Registering of farm practices with Farm Accountancy Data Network Sand region (yellow) farms, sampled 1-6 years 21 (2.5 years) 7 (2.2 2 years) 8 pig and crop-livestock farms (1.8 years) heath old ag field sandy soils (podzol) Nitrogen surplus and nitrate 13 Nitrogen surplus and nitrate 14 Sampling of upper meter of groundwater sampling probe Deriving a (NLF) Collar Øout = 1 mm,1 m,4 m Tube pvc Øout = 16 mm borehole Ø=7mm tube PE, Øin = 4 mm Øout = 6 mm groundwater level = screen PVC, Øin=13 mm Øout=16 mm split width =.3 mm.3 m.5 m 16 boreholes per farm Nitrogen surplus and nitrate 15 Nitrogen surplus and nitrate 16 versus Nitrogen (kg/ha/year) / 25 2 versus Nitrogen (kg/ha/year) 25 Average of all in one year years 1 13 years Nitrogen surplus (kg/ha/year) Nitrogen surplus and nitrate Nitrogen surplus (kg/ha/year) Nitrogen surplus and nitrate 18

4 versus Nitrogen (kg/ha/year) / no grassland y =,58 x + 42 R 2 =,41 8% grassland y=64x-27,64 R 2 =, Nitrogen surplus (kg/ha/year) Nitrogen surplus and nitrate 19 Nitrogen (NLF) Soil type Drainage type Arable land Grassland Sand Well and deep.89 ±.1.46 ±.6 Moderately.58.3 Poor and shallow.38.2 Clay.36 ± ±.3 Peat -.4 ±.2 NLF is indication for the influence of denitrification NLF =. full denitrification NLF = 1. no denitrification Nitrogen surplus and nitrate 2 Nitrogen (NLF) Question Is there an effect of time lag? - decreased with time - we related to the of only the previous year - this might overestimate the NLF Trend in and N (kg/ha/year) [ or ] Nitrogen surplus and nitrate Agricultural year Nitrogen surplus and nitrate 22 Trend in and N (kg/ha/year) [ or ] 4 Farm practices in Accounting for time lag N (kg/ha/year) [ or ] /3/2/1 NLF: -7% 5/3/2: NLF -5% Nitrate-N in groundwater in summer Agricultural year Nitrogen surplus and nitrate Agricultural year Nitrogen surplus and nitrate 24

5 Findings Consequences for policy makers Leaching (NLF) from arable land is higher than from grassland Leaching (NLF) for well drained soils is higher than from poor drained soils Accounting for time lag gives 5-7%-points lower values for NLF s Integration of monitoring farm practices and the quality of the environment has many advantages Data acquired by trend monitoring networks may be used for underpinning i policy decisions i Small investment in additional measurements to underpin models may pay off Nitrogen surplus and nitrate 25 Nitrogen surplus and nitrate 26 Validation of NLFs with special project data Field N input / output Model A2 1 research-supported commercial 1 research farms Thank you for your attention Nitrogen Leaching Fraction Compare: - observed - calculated Model B2 NO 3 concentration calculated Nitrogen surplus and nitrate 27 Nitrogen surplus and nitrate 28 Validation of NLFs with special project data Conclusion: model slightly overestimates s Observed in upper meter of groundwater (mg/l) NLFs should be lower? - local rainfall? - immobilization? Calculated l ti in upper meter of groundwater (mg/l) Nitrogen surplus and nitrate 29 NLF versus NLF (-) surplus (kg/ha/year) Nitrogen surplus and nitrate 3

6 NLF versus precipitation surplus NLF (-) precipitation surplus (mm/year) Nitrogen surplus and nitrate 31