title: Monitoring nitrogen leaching for the evaluation of the Dutch minerals policy for agriculture in clay regions.
abstract: This paper presents the results of the Dutch monitoring program for agriculture in the clay regions for the period 1996-2000 and evaluates the monitoring strategy. A wide range of farms (25 to 85%) had a NO3--N concentration in tile drainwater higher than the EU standard of 11.3 mg/l. The low figure is related to wet winters; the high, to dry winters. Arable farms are more prone to NO3- leaching than dairy farms. On arable farms, about 25% of the N surplus leached to groundwater and tile drainwater, on dairy farms this was about 15%. N in tile drainwater has shown to be the best indicator for monitoring the effects of farming practice changes in the clay regions. The average NO3--N concentration in tile drainwater was 18.8 and 3.2 mg/l in borehole water on farms where both were monitored. It is known that N use has a relationship with NO3- in tile drainwater and not with NH4+ and organic N. The presented results indicate that crop rotation and precipitation strongly influence NO3- concentration in tile drainwater.
authors.affiliation: National Institute of Public Health and the Environment, Bilthoven, The Netherlands. B.Fraters@rivm.nl
authors.forename: D
authors.initials: D
authors.lastname: Fraters
authors.forename: L J
authors.initials: LJ
authors.lastname: Boumans
authors.forename: T C
authors.initials: TC
authors.lastname: van Leeuwen
authors.forename: W D
authors.initials: WD
authors.lastname: de Hoop
mesh_terms: D000383:Agriculture / Q000331:legislation & jurisprudence* / Q000592:standards / Q000706:statistics & numerical data / Q000639:trends; D000538:Aluminum Silicates / Q000032:analysis*; D000818:Animals; D002417:Cattle; D000077215:Clay; D003612:Dairying / Q000331:legislation & jurisprudence / Q000592:standards / Q000706:statistics & numerical data / Q000639:trends; D004784:Environmental Monitoring / Q000331:legislation & jurisprudence* / Q000379:methods / Q000592:standards* / Q000706:statistics & numerical data; D006801:Humans; D008903:Minerals / Q000378:metabolism* / Q000592:standards*; D009426:Netherlands; D009566:Nitrates / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D011640:Public Policy; D012987:Soil / Q000032:analysis; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000592:standards; D014877:Water Pollution, Chemical / Q000331:legislation & jurisprudence / Q000517:prevention & control / Q000706:statistics & numerical data
chemical_list: D000538:Aluminum Silicates; D008903:Minerals; D009566:Nitrates; D012987:Soil; D014874:Water Pollutants, Chemical; D009584:Nitrogen; D000077215:Clay