csu extensions
csu nutrient

Best Management Practices – Irrigation Water Nitrogen Credits

Quick fact sheet to support irrigation water nitrogen crediting.

  • Nitrogen credits are part of the Right Rate in 4R nutrient management.
  • Irrigation water in some parts of Colorado contains significant nitrate-nitrogen
  • Nitrate in irrigation water is immediately available for crop uptake
  • Nitrate concentrations greater than 10 ppm are most likely to have reduced N fertilizer requirements
  • Irrigation water should be sampled for nitrate as part of any nitrogen recommendation in areas of high groundwater nitrate
  • Nitrate-N ppm x 0.23 x inches of water applied = N credit (lbs/acre) or an acre-inch of water contains 0.23 lbs of N for each ppm of nitrate-N