September 29, 2025 (AMES, Iowa) — The Iowa Nitrogen Initiative (INI) team announced updates to N-FACT, Iowa State University’s dynamic nitrogen fertilizer decision support tool. The updates incorporate user feedback and are intended to improve ease-of-use and deeper understanding of the tool and its outputs.
Since release in February 2025, N-FACT has been used by nearly 4,500 unique visitors wanting to learn more about optimum nitrogen rates for corn in Iowa. INI staff and partner organizations have met with hundreds of farmers, crop advisers, industry representatives and government staff to demonstrate the tool and engage in discussion about its usability.
Key improvements include:
- On-farm trials: updates to this page are focused on data visualization. The graphs for economic optimum N rate, yield at the economic optimum N rate, and lbsN/bu at the bottom of the page now update based on the filters applied to the table. When users sort by year, region, or previous crop, they will immediately see the results reflected in these figures.
- Future updates will include the ability to filter by N application timing, planting data, and annual/location specific precipitation (dry/average/wet). Data from 2025 trials will be uploaded in March 2026.
- Estimate your optimum N: after location is selected, a pop-up box provides average values for soil organic matter (SOM) and local precipitation for spring and summer. These values drive the location-to-location differences in calculator results for optimum N rate and modeled yield. If a user knows that their SOM or precipitation is much different than the values used in the model, they should consider the results in context of their operation.
- Additionally, this pop-up includes guidance about selecting dry, average, or wet precipitation during the weather input selection of the tool. The full list of county precipitation and SOM data is also available on the FAQ page.
- A future version of N-FACT may allow for users to input user-specific SOM into the tool.
The INI team encourages users to continue to provide feedback as they use the tool for 2026 N fertilizer recommendations.