title: Variation in nitrogen use efficiencies on Dutch dairy farms.
abstract: BACKGROUND
  On dairy farms, the input of nutrients including nitrogen is higher than the output in products such as milk and meat. This causes losses of nitrogen to the environment. One of the indicators for the losses of nitrogen is the nitrogen use efficiency. In the Dutch Minerals Policy Monitoring Program (LMM), many data on nutrients of a few hundred farms are collected which can be processed by the instrument Annual Nutrient Cycle Assessment (ANCA, in Dutch: Kringloopwijzer) in order to provide nitrogen use efficiencies.
  
  
  RESULTS
  After dividing the dairy farms (available in the LMM program) according to soil type and in different classes for milk production ha(-1) , it is shown that considerable differences in nitrogen use efficiency exist between farms on the same soil type and with the same level of milk production ha(-1) .
  
  
  CONCLUSIONS
  This offers opportunities for improvement of the nitrogen use efficiency on many dairy farms. Benchmarking will be a useful first step in this process.
authors.affiliation: LEI Wageningen UR, The Hague, The Netherlands.
authors.forename: Co Hg
authors.initials: CH
authors.lastname: Daatselaar
authors.affiliation: LEI Wageningen UR, The Hague, The Netherlands.
authors.forename: Joan R
authors.initials: JR
authors.lastname: Reijs
authors.affiliation: Wageningen UR, Plant Research International, Wageningen, The Netherlands.
authors.forename: Jouke
authors.initials: J
authors.lastname: Oenema
authors.affiliation: LEI Wageningen UR, The Hague, The Netherlands.
authors.forename: Gerben J
authors.initials: GJ
authors.lastname: Doornewaard
authors.affiliation: Wageningen UR, Plant Research International, Wageningen, The Netherlands.
authors.forename: H Frans M
authors.initials: HF
authors.lastname: Aarts
mesh_terms: D000818:Animals; D003612:Dairying; D005308:Fertilizers; D006801:Humans; D008892:Milk / Q000378:metabolism*; D009426:Netherlands; D009584:Nitrogen / Q000378:metabolism*; D012987:Soil
chemical_list: D005308:Fertilizers; D012987:Soil; D009584:Nitrogen
keywords: dairy farms; efficiency; nitrogen use efficiency; variation