Field evaluation of a model for predicting nitrogen losses from drained lands

J Environ Qual. 2006 Oct 27;35(6):2026-42. doi: 10.2134/jeq2005.0249. Print Nov-Dec 2006.


The N simulation model, DRAINMOD-N II, was field-tested using a 6-yr data set from an artificially drained agricultural site located in eastern North Carolina. The test site is on a nearly flat sandy loam soil which is very poorly drained under natural conditions. Four experimental plots, planted to a corn (Zea mays)-wheat (Triticum aestivum L.)-soybean (Glycine max.) rotation and managed using conventional and controlled drainage, were used in model testing. Water table depth, subsurface drainage, and N concentration in drain flow were measured and meteorological data were recorded continuously. DRAINMOD-N II was calibrated using the data from one plot; data sets from the other three plots were used for model validation. Simulation results showed an excellent agreement between observed and predicted nitrate-nitrogen (NO(3)-N) losses in drainage water over the 6-yr period and a reasonable agreement on an annual basis. The agreement on a monthly basis was not as good. The Nash-Sutcliffe modeling efficiency (EF) for monthly predictions was 0.48 for the calibration plot and 0.19, 0.01, and -0.02 for the validation plots. The value of the EF for yearly predictions was 0.92 for the calibration plot and 0.73, 0.62, and -0.10 for the validation plots. Errors in predicting cumulative NO(3)-N losses over the 6-yr period were remarkably small; -1.3% for the calibration plot, -8.1%, -2.8%, and 4.0% for the validation plots. Results of this study showed the potential of DRAINMOD-N II for predicting N losses from drained agricultural lands. Further research is needed to test the model for different management practices and soil and climatological conditions.

Publication types

  • Evaluation Study
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Agriculture*
  • Calibration
  • Environmental Monitoring*
  • Fertilizers
  • Forecasting
  • Models, Biological
  • Nitrates / analysis
  • Nitrogen / analysis*
  • North Carolina
  • Soil Pollutants / analysis*
  • Soybeans
  • Time Factors
  • Triticum
  • Water Pollutants / analysis*
  • Water Supply*
  • Zea mays


  • Fertilizers
  • Nitrates
  • Soil Pollutants
  • Water Pollutants
  • Nitrogen