FAQ about N-Time technology: Leaf firing, cloud cover, base rates, and more

With all the new technology making its way into agriculture, it’s only natural to have some skepticism around new products. Not every software or tool works the way it’s supposed to. Not every innovation is helpful. Not every variable can be controlled, no matter how fancy the tech. 

We’ve even experienced some of this (valid!) skepticism from Sentinel customers. When they first learn about N-Time — or even after they’ve integrated it onto their acres — some common questions about the technology tend to pop up. 

The good news is: these “gotchas” about N-Time are ones we’ve probably heard before — and have answers to.  

Here’s a look at some of the top hesitations or concerns about N-Time we hear from customers, plus how we approach solving them: 

1. Why is my bottom leaf firing? 

Every year, without fail, customers come to us with concerns about bottom-leaf firing. And that’s only natural: If this is happening in your fields, it could be a sign something is wrong. 

When customers see this, their first reaction is often: does this mean N-Time didn’t work? Is my crop nitrogen deficient? 

But don’t worry. Leaf firing does not mean the technology isn’t working.

When this happens, we have to question: Is this symptom truly because of nitrogen deficiency, or are other factors causing it? Here are some other possibilities: 

• Not enough water in the field (in this case, applying more nitrogen wouldn’t actually solve the problem)

• A problem with another nutrient (sometimes other nutrient deficiencies harm nitrogen availability)

• Sometimes, leaf firing might not actually impact yield. It might not look pretty — but it doesn’t always harm your bottom line.

In the reproductive growth stages — even at optimal nitrogen efficiency — we do anticipate there would be some leaf firing at the very lowest leaves of the canopy. Not a lot of light makes it down to those leaves, so there isn’t as much photosynthesis happening. But that’s okay. It’s better to have nitrogen at other places in the crop, rather than the bottom.  

What happens if there are gaps in imagery for several days?

N-Time technology relies on satellite imagery to monitor crop health and detect early signs of nitrogen deficiency. So it’s only natural to ask: okay, so what happens when you can’t get imagery? 

Typically, we get satellite images three to four times a week that are quality enough to use to make nitrogen application recommendations. 

But just like any other aspect of farming, we at least partially depend on the weather. In most years, there will be a few-day stretch where we don’t get imagery because of cloud cover. This is a known concern. But here’s how we deal with fluctuating weather and cloud cover (especially in regions with more moisture): 

• We offer a crop nitrogen model that can be used to inform nitrogen rates for one week or more. We calibrate our model with imagery to make its recommendations as similar to imagery as possible.

• We create nitrogen prescriptions based on the most recent imagery readings. Often, this means prescribing a smaller nitrogen application to sustain the crop for a few days until imagery clears up and N-Time can create the next full recommendation. 

• We’re also exploring alternative data sources (from drones or handheld sensors, for example) when satellite imagery is unavailable. 

Using satellite imagery to inform your nitrogen application strategy is no different from any other farming practice. Just like with irrigation, hybrid selection, or harvesting technology, it’s important to have a plan B if the situation fluctuates. 

Your nitrogen management backup plan might include: 

• Planning for a small, flat-rate application to keep you comfortable until imagery comes in

• Scouting to assess crop needs

• Collecting tissue samples to temporarily inform your action

How do I choose an appropriate base rate? 

Your nitrogen base rate is one of the most important early-season decisions you’ll make. But it’s never an easy choice. 

N-Time is designed to give in-season nitrogen application recommendations, and we don’t currently give base rate recommendations to producers.

Some producers will apply a low amount of nitrogen (or even none) prior to emergence, then wait for N-Time to give early-season recommendations. However, there’s not a lot of crop biomass at this point in the season, which means there is some risk to waiting until more emerges. This could potentially lead to a nitrogen deficiency before N-Time imagery is able to appropriately measure crop needs.

To counteract this risk, here are a couple of pathways we suggest for first-time customers: 

• Option #1: Stick with a base rate that’s below your current base rate and you’re confident will sustain the crop until the mid-vegetative stages. Then leverage N-Time from the V7 stage and beyond to make future applications.

Option #2: Take a stairstep approach before making a wholesale change at your operation. Keep your base application rate, but integrate a few Sentinel plots in order to build trust in the system within the first year. We can work together to gradually reduce your base rate in subsequent years — and save you future input costs. 

Every farm is different. But in general, we support base rates between 60 and 120 lb-N/ac, depending on your soil type and post-emergence application plans.

Coming soon: We’re working on a new base rate simulator to help farmers decide their best base rate under different weather scenarios. (Remember: too low of a base rate could lead to higher risk exposure.)

How to leverage Sentinel for more certainty, efficiency, and money saved 

There is no certainty in agriculture — especially in nitrogen management. But there are steps you can take to increase your level of certainty and mitigate your risk. 

That’s where N-Time comes in. If you’re curious how to integrate this technology onto your acres to optimize your nitrogen applications, improve your nitrogen use efficiency, save input costs, and yield a healthier crop, reach out to the Sentinel Fertigation team today.