Extreme season proves modeling nitrogen pays

The 2019 growing season was certainly memorable, but it may be one that many would like to forget. Despite the stress it put on both growers and input suppliers, I feel there are many lessons to be learned in such an extreme year.

Last year, MFA used a new nitrogen-modeling tool called Nutri-Track N. It was certainly an interesting year to roll out this new technology. While we had been experimenting and demon­strating Nutri-Track N since 2016, last year was the first time we had such extreme potential for nitrogen loss. Previously, we had seen this recommendation tool help improve nitrogen use efficiency to 0.8 pound of nitrogen for every bushel of corn yield in many areas. That wasn’t possible in 2019, with excess rainfall pushing nitrogen below the root zone of the corn crop before it could be utilized.

During the past growing season, it took significantly more nitrogen to raise a bushel of corn than it did in previous years. For example, in one field where a check strip was left with no top-dress application, there was a 40-bushel per acre yield penalty. Nutri-Track N let us see the trend developing and respond appropriately, which is exactly what we hoped would happen. This recommendation system allows us to tailor nitrogen applications to the current weather pattern.

What makes the Nutri-Track N system different? It is based on years of university research that explains and models nitrogen’s life cycle in a field. It collects rainfall, tempera­ture, soil data and all the agronomic field practices we can provide, and then it estimates the amount of N that is available when the crop needs it most and models the need moving forward. Not only does it track what nitrogen is applied but also estimates what has been min­eralized from soil organic matter (OM). The more information we can feed to the program, the better the recommendation.

The best recs are achieved with the combination of grid sampling to provide OM levels and historic yield data to give us variable yield potential. By evaluating all these factors, Nutri-Track N shows the current status of the field and where it is expected to be at the end of the season—assuming typical weather patterns. The model is constantly improving by updating every night with new adjustments based on the previous day’s actual recorded weather.

In practice last year, this tech­nology worked as we had hoped. In mid-May, the MFA Precision Agronomy team started to send out alerts to our staff, warning that fields with unprotected fall nitrogen applications were at extreme risk of running short of this essential plant nutrient. By late May, we began to see more fields—even some that had received spring applications— that would benefit from topping off the nitrogen mid-season. The windows were tight to get that N applied, but it paid dividends when the combines rolled this past fall. In my estimation, nitrogen manage­ment was second only to stand es­tablishment in terms of importance to overall yields in 2019.

So, what did we learn from last year?

• While we’ve always understood that using split applications with a planned top-dress application could improve nitrogen use efficiency, this past season, the system paid big yield dividends as well.
• The later we can wait to make our overall total nitrogen invest­ment, the better off we are. The more information we have about our growing season, the better N rate decisions we can make.
• Protecting your nitrogen with proven stabilizers pays. Any­thing we can do to maintain nitrogen in the ammonium form in the soil for a longer period is critical, not only to protect your investment but also keeping that nitrate out of surface waters.
• There is no single right rate or application method for all of our nitrogen needs. It is a system with many variables. However, with the right tools we can con­tinue to improve efficiency and yields as we gain experience and knowledge.

I’m excited to see the results from those producers who used Nutri-Track N last year. While no two years are the same, I feel confi­dent that we are managing nitrogen better today and will continue to improve into the future.