Jason Richters
I had a desire to improve my nitrogen use efficiency, so I decided to try the Sentinel Ag nitrogen management system three years ago. The ability to know if the crop needs a nitrogen application based on satellite imagery is a game changer, and we have learned that we can better manage and reduce our nitrogen application rates while maintaining yields. This is good for our bottom line and may eventually reduce nitrate levels in our groundwater.
Using a nitrogen management system is a management change, but more importantly, it’s been a management improvement. I encourage other farmers to try this technology, especially if they are already split applying their nitrogen.
Tyler Smith
My experience is a little different than most producers because I was able to be a part of the development of the concept that grew into Sentinel Ag with my role at UNL. As far as my personal farm operation, I had started fertigating about 15 years ago and had seen the benefits of spreading out my nitrogen applications, but there were years where I wondered if I needed that last fertigation.
After Sentinel became commercially available, I could see the promise of the method and I enrolled a couple of fields in 2022 and 2023. I was realizing nitrogen savings without losing yield. In 2024 and 2025, I’ve had all of my irrigated corn acres enrolled and I’ve been able to lower my nitrogen use by 10-40% while achieving several new field best yields.
What I’ve observed is that nitrogen availability is so variable, in both total growing season need and the timing of that need, that I don’t know how I can ever hope to accurately predict it. It’s much easier to let the corn tell me when it needs it and, at the end of the season, I’ll know what the total need was, not at the beginning. We don’t decide how much irrigation we will need for the next growing season in November or March; it’s a real-time decision that we make as we go through growing season that accounts for changes in weather, yield potential, ROI, etc. We have the ability to manage nitrogen the same way that accounts for all of the unknowns in real-time with a sensor-based approach.
Scott Richert
I started my in-season nitrogen a while ago with the N-Sense program, using sensors on a Hagie sprayer. I had been sidedressing for years but wanted to see if I could get better. What I found was I was close. I was putting on enough to have a good yield, but the sensors had better ROI. From there, we kept adjusting, and when the Sentinel program came out, I put two fields in.
I found the same thing that I was getting a good yield, but the sensors were having a better ROI. So, ROI is great, but the other thing that means is that I was overapplying nitrogen. In the Upper Big Blue NRD, I live in one of the areas that has not moved up on the list for testing and reporting. Looking at how the numbers have been moving, though, it’s just a matter of time.
For my soil, it takes 30 years for the nitrate to make it to the water table. It basically takes most of a farming career for the nitrogen you apply to make it to the aquifer. If we want to make things better for the people who come behind us, we need to make changes now.
With in-season application, I have nitrogen in the system only when my crop is there and using it. I have the nitrogen that the crop needs now, not for the whole season. If we have adverse weather, I can adjust to that. If it is hailed out, I save the balance of my fertilizer and don’t let it leach away. If the plant is telling me it needs more, I can put it on. If the mineralization is really good, the plant will tell me it is happy and I can save an application.
There are some issues to work through. You don’t really know how much nitrogen you are going to use on each farm each year. You may need to purchase more later in the season, or you may need to store some until next year. Sometimes it has been hard to apply when you want. It can rain at an inopportune time, but I’ve never not gotten the application done. The sensors have a seven-day window of time to make an application.
Todd Schmieding
Sentinel has allowed me to manage nitrogen as it is needed on the field. It accounts for release from cover crops in a way that gives me the full credit when it is available. It does add challenges in timing and changing when my work occurs, as it is not predictable. I have also seen changes in status before I applied the nitrogen, creating additional questions as to what is happening in the field.
If you’re considering adding this to your program, start on one field at first and then expand from there.
Jesse Williams
Using in-season nitrogen application through the pivot allows you to spread the applications out and “spoon-feed” the crop. Adding a sensor system such as Sentinel provides an additional tool to monitor crop needs. The big benefit to this, in my mind, is the ability to apply nitrogen based on crop needs and potential throughout the season. Applying a full rate upfront of 1-1.2lb per expected bushel can prove to be extremely wasteful if you encounter weather-related issues such as hail, heavy rainfall or wind damage.
Using the spoon-feed approach with fertigation for the last three years, I have typically been able to keep my nitrogen use under 0.8lb per bushel.
Challenges for me have been gaps in imagery due to cloud cover/smoke. This year, I probably shot from the hip more on applications due to the fact that I was going a week or more between imagery updates and trying to time applications between rainfalls.
Source : unl.edu