A deep dive into the 4Rs starts where the original Nitrogen Smart ends with a detailed discussion on N rate, the contributions from soil and the stress from climate factors.

The 4Rs promote a nutrient management approach that balances crop productivity with environmental preservation:

  • Right rate – Nitrogen rates have the potential to make the largest impact on both crop production and the environment. The key to optimizing rates is to follow university N guidelines, use soil nitrate-N tests when appropriate, and scout for deficiencies.
  • Right source – Once in a plant-available form, the plant doesn't distinguish one N source from another. However, there are differences in how N fertilizers interact with the environment, which can affect both availability and loss.
  • Right time – The nutrient supply should be synchronized with crop demand and uptake. Several factors influence N availability, including fertilizer source, the use of stabilizers or inhibitors, and field conditions. Together they help determine when it's most appropriate for that particular N source to be applied.
  • Right place - Nutrients should be placed where the crop can use them. Consequently, the application method is important for optimum fertilizer efficiency.
Nutrient Management
Online Course


Self Paced
Training Type
Online Learning

United States


This course is free, but it requires registering through the University of Minnesota