N-FACT leverages on-farm nitrogen rate trial data from the Iowa Nitrogen Initiative to refine millions of simulated data points in the Agricultural Production Systems Simulator, or APSIM.

For this version of N-FACT, our team selected inputs that make the most difference to the optimum N rate as supported by existing data. Future versions will incorporate additional management options.

In the current version of N-FACT, there are over 23,000 possible scenarios. Each input (field location, weather, residual nitrogen, planting date, prices) represents a range of data points. If your new combination doesn't result in a different optimum nitrogen rate, the change you made may still fall within the range of your previous selection. With additional years of on-farm trial data, we can further refine those ranges to allow more specific selections, resulting in even more possible scenarios.

The economic optimum N rate and yield are influenced by complex interactions between soil, weather, and crop management. N-FACT targets several of the most influential interactions but cannot feasibly capture all of them. If values aren’t what you’d expect, it could be due to differences on your farm compared to our statewide assumptions. In this version of the tool, we assume the state had the same crop residue management, plant populations, and hybrid, which could differ on your field. It also assumes that other yield limiting factors like pests, soils, pH, and other nutrients are appropriately managed.

We anticipate releasing new versions every 12-18 months, for as long as this program remains funded. New features will be developed based on discoveries through our on-farm trials and the needs of Iowa's farmers.

Any farmer in Iowa who can apply nitrogen using a variable rate prescription and has a combine with a yield monitor. Enrollments are accepted year-round; contact us to learn more.

The standard trial uses five replicate blocks of five N rates. Our precision agronomists work with the farmer to determine which rates to test, based on the farmer's nitrogen program (timing, source, and applicator capabilities). The agronomist then designs the trial as a variable rate prescription that is applied during that farmer's regular nitrogen application. The participant sends the as-applied nitrogen data and the harvest data (yield file) to our data analysts.

About five to ten acres, depending on the size of your equipment and the capabilities of your applicator. Each individual rate block is about .25 - .33 acre, and there are up to 25 rate blocks in a trial.

We collect a vast amount of management data for each trial. As more trials are conducted, we will be able to analyze the impact of different management practices on optimum nitrogen rate. While we don't conduct product trials, we are happy to help farmers design their own product trials as part of their INI trial.

The INI is funded on a year-by-year basis. There is currently no sunset date on the on-farm trials. As long as farmers are innovating and the weather changes, we can improve our understanding of nitrogen science.