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University of Minnesota Extension

Advanced Nitrogen Smart: A deep dive into the 4Rs

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.



Thanks to the generous support of the Minnesota Corn Growers, there is no charge for the Nitrogen Smart course.


This is a self-paced course. If you need to leave the course before you finish, you may come back anytime. Your progress is automatically saved and you should return where you left off.

Online enrollment instructions

  1. When you click on the "Enroll in Nitrogen Smart" button below, you will go to the enrollment page. Pick the Deep dive: 4Rs section and select "Add to cart." Proceed to "Checkout."
  2. After you have clicked "Checkout," you will either log in or create a new University of Minnesota guest account to access the course.
    • Note that your email address will be used as your UMN "internet ID" for this course. Please also note that University passwords must be 16 characters long. We recommend using a phrase you can remember.
  3. After creating your course login information, you will be directed back to the enrollment checkout process. Fill in only the required information as indicated by an asterisk (*) and "Continue checkout."
  4. You're now enrolled in the course! You will receive a confirmation email with a link to access the course.

Go to the course page

The Nitrogen Smart workshops are also offered at locations around the state throughout the year. Visit the course page for more information.

Course page

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