Illinois Fertilizer & Chemical Association
Supply · Service · Stewardship

Fall Ammonia Application Guidelines

The Illinois Nutrient Research & Education Council (NREC) is now in its 7th year, and the projects that NREC has invested in relative to nitrogen management are resulting in a much greater understanding of nitrogen movement in the soil and uptake by the crop.  
It has long been a challenge to assure widespread compliance with voluntary standards when it comes to the application of anhydrous ammonia in the fall.  But thanks to extensive research and tracking of nitrogen movement in the soil as well as agronomic response to various nitrogen timing and rate studies, we have a much better understanding of what is occurring in Illinois soils. 
When it comes to determining a judicious time begin fall ammonia application, IFCA has worked closely with the University of Illinois to engage in on-farm research that helps give us a better idea of when it's appropriate to being fall application based on soil temperature, soil conditions and the weather outlook.  As our members plan for a successful fall that embraces the 4Rs, watch for a bulletin from the UI that will provide guidance on when it is appropriate to begin fall application this year.  IFCA will communicate this information to you as well when it become available.  It will coincide with falling soil temperatures.    
The IFCA 4R Code of Practice stresses the inclusion of a labeled nitrification inhibitor in all fall applied ammonia. You should also consult the Nitrogen Calculator as you work with your customers to determine the rate for your region of the state.  The Calculator is also available as an app, just type "mrtn" in the App Store on your smart phone.  The Calculator includes all of the results from NREC funded nitrogen rate research trials in Illinois, conducted in all regions of the state.  The rates recommended by the calculator reflect the maximum return to nitrogen (MRTN) that assures optimum agronomic results, economic return and environmental stewardship.  The 4R Code of Practice also encourages splitting the nitrogen rate to help mitigate risk of nitrogen loss from uncontrollable weather events.  If you have questions about nitrogen management and the 4Rs please contact Dan Schaefer at