Measuring and modelling nitrogen transformations in a tile-drained Fragiaqualf under arable cropping 2. Leaching losses of nitrogen in a barley — oats rotation

Abstract

Nitrogen (N) transformations in 2 field plots under a barley — oats rotation (one with and one without N fertiliser) were simulated over 2 years with a modified version of the crop - season N model described in the first paper in this series. The predicted N loads and concentrations in tile drainage from the plots agreed well with the measured values. Nitrate concentrations in tile effluent often exceeded 10 mg N/litre on the plot that received no N fertiliser. Fertiliser urea at 100 kg N/ha increased nitrate levels to about 50 mg N/litre, but only for a short time. Simulations suggest that N leaching losses from the soil could be 50070 lower under crop than under fallow. Simulations of this kind could be used to assess environmental pollution in catchments fed by tile drain discharges.

Keywords:

• models
• nitrogen
• fertilisers
• barley
• oats
• rotational cropping
• irrigation
• tile drainage