An integrated assessment of nitrogen source, transformation and fate within an intensive dairy system to inform management change

PLoS One. 2019 Jul 23;14(7):e0219479. doi: 10.1371/journal.pone.0219479. eCollection 2019.

Abstract

From an environmental perspective optimised dairy systems, which follow current regulations, still have low nitrogen (N) use efficiency, high N surplus (kg N ha-1) and enable ad-hoc delivery of direct and indirect reactive N losses to water and the atmosphere. The objective of the present study was to divide an intensive dairy farm into N attenuation capacity areas based on this ad-hoc delivery. Historical and current spatial and temporal multi-level datasets (stable isotope and dissolved gas) were combined and interpreted. Results showed that the farm had four distinct attenuation areas: high N attenuation: characterised by ammonium-N (NH4+-N) below 0.23 mg NH4+-N l-1 and nitrate (NO3--N) below 5.65 mg NO3--N l-1 in surface, drainage and groundwater, located on imperfectly to moderately-well drained soils with high denitrification potential and low nitrous oxide (N2O) emissions (av. 0.0032 mg N2O-N l-1); moderate N attenuation: characterised by low NO3--N concentration in drainage water but high N2O production (0.0317 mg N2O-N l-1) and denitrification potential lower than group 1 (av. δ15N-NO3-: 16.4‰, av. δ18O-NO3-: 9.2‰), on well to moderately drained soils; low N attenuation-area 1: characterised by high NO3--N (av. 6.90 mg NO3--N l-1) in drainage water from well to moderately-well drained soils, with low denitrification potential (av. δ15N-NO3-: 9.5‰, av. δ18O-NO3-: 5.9‰) and high N2O emissions (0.0319 mg N2O l-1); and low N attenuation-area 2: characterised by high NH4+-N (av. 3.93 mg NH4+-N l-1 and high N2O emissions (av. 0.0521 mg N2O l-1) from well to imperfectly drained soil. N loads on site should be moved away from low attenuation areas and emissions to air and water should be assessed.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Agriculture
  • Ammonium Compounds / analysis
  • Dairying*
  • Geography
  • Nitrogen / analysis*
  • Nitrous Oxide / analysis
  • Oxygen Isotopes / analysis
  • Oxygen Radioisotopes / analysis
  • Soil
  • Time Factors
  • Waste Management*
  • Water / chemistry

Substances

  • Ammonium Compounds
  • Oxygen Isotopes
  • Oxygen Radioisotopes
  • Oxygen-15
  • Oxygen-18
  • Soil
  • Water
  • Nitrous Oxide
  • Nitrogen

Grants and funding

S.F.T., S.A.R., K.K., K.D., M.G.H., G.E., J.v.C. and O.F. gratefully acknowledge the financial support from the European Commission Union through Marie Skłodowska-Curie scholarship provided in the framework of the INSPIRATION Innovative Training Network. E.C., J.M. and P.T. acknowledge funding under the Teagasc Walsh Fellowship Programme. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.