Satellite Imagery Can Test, Check and Confirm: A Farmer’s Perspective

Sally Krueger

Apr 24, 2019

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Brian Petty farms in Alexandria, Indiana, and he’s using satellite imagery from the FBN network to:

  • Help gauge overall crop health

  • Test corn hybrid performance based on different management practices

  • Confirm if spray applications are working post-application

  • Check on any suspected problem areas in fields

  • Be another, broader “set of eyes” on things he cannot see happening in his fields

“I'm looking for differences in the crop from the image and often these differences are not visible in the field. The neat thing about this is you can relate it to data you have and things you know. For example, with an application you likely have the data from the applicator to correlate to something you might see from the satellite. This is great and you can answer many questions and gauge crop response and allow you to experiment.

But the other often not discussed aspect is the things you do know, or think you know....maybe you have always known a poorly drained area of a field is hurting your production. What the satellite image does is tell the story from above, that maybe that area is bigger than you realize, or that it should be addressed sooner on your priority list.”

Here’s how Brian used satellite imagery specifically around a fungicide application on corn this season.

He shared a little bit about it on Twitter, and we’re breaking it down with him even further here.

How have you used satellite imagery around your in-season corn fungicide applications?

“This is ongoing, but our expectation was to apply fungicide and hopefully be able to detect a crop response at some point—but our expectation was that through the imagery it would be barely distinguishable from a non-applied area. What has blown us away so far has been the very clear defining lines in crop health that have appeared in an applied area of the image compared to a non-applied area. And these responses have shown up at around 10 days post-application time, showing how quickly the product began to work and what all we could see.

Additionally, as the satellite images will continue to come in for the rest of the season we get to follow this crop response to crop maturity so it’s not a "one off" event. Another interesting facet is in a couple of fields where we have applied differing products with differing modes of action, and now with the satellite images we get to gauge crop response and how long that response lasts.”

How does satellite imagery help you manage practices on the different hybrids you plant?

“We plant many different corn hybrids on our farm with varying amounts of resistance to Gray Leaf Spot (GLS) from one variety to another. When it comes to the decision whether to apply fungicide, we look at many factors such as presence of disease, are conditions supportive to the disease propagating, and other factors. One of the most important points we look at is how resistant a hybrid might be to disease pressure and will it be profitable to apply a fungicide to it? In what I labeled the “GLS hybrid test” [in the images], this particular hybrid is very resistant to GLS, and we only sprayed fungicide in strips on a small percentage of the field. Our goal was to look for a crop response, despite the known factor that this disease is less likely to easily propagate through this variety. The response was rather shocking from the satellite imagery showing clearly defined "healthier" areas that the test strips were applied on.”

When you first looked at this relative image layer, what did it indicate to you?

“I immediately recognized where the sprayer applied product and where he did not. Visually, on the ground around the time this image was taken, you could walk that dividing line between the green and yellow/red and see no real crop response. The EVI imagery from the satellite is showing a clear, healthy response from the crop right down to the last pass where the applicator ran out of product.”

What does this application layer image tell you that you didn't know before?

“This is the as-applied map from the sprayer that shows exactly where fungicide was applied. You can cycle between this map and the satellite image and see the crop response to applied product, even down to the end row or headland on the west end of the field. Interestingly, the last pass from the sprayer (north side), he [operating the sprayer] ran out of product as he got within a couple hundred feet of the west end row. This gap is clearly visible on the satellite health index as well.”

What does this image tell you is happening in those high-biomass, green areas of the image versus the others?

“This is the hybrid that we expected almost no response from. Generally, the data from this hybrid suggests that versus some others we grow that fungicide is not likely to be economical to apply due to its genetic resistance to GLS. We chose to only run test strips of product on this field specifically to gauge crop response. To our surprise, this image clearly shows those applied strips. It makes us question the other unknowns in positive plant health from fungicide applications— what other diseases might be present that perhaps we overlooked? We don't know all the exact answers yet, but look forward to more images as they come in over time.”

What does this next image tell you about whether a particular practice is working well?

“This is the as-applied map for the ‘test strips’ for the satellite image above. It is interesting to see on the eastern sprayer pass how the coverage gap between the first and second pass shows up in the satellite image. This tells us that product application was very controlled (no drift) and that the satellite imagery was of sufficient resolution to capture this small gap of coverage in the image.”

Is it easy to use FBN satellite imagery?

“My primary usage has been on the desktop, and I don't know how it could be any easier. All that is required is to login and select the field you want to view! One great feature is the view of the different images from the satellite that you can cycle through to see crop response throughout the season.”

Overall, why is satellite imagery a valuable tool for your farm?

“I see satellite imagery as giving us a different perspective. Ground truthing is important, but by utilizing satellite imagery you can get an overview of all of your fields all at once and draw your attention to potential problem areas of fields to focus on. We are also excited to see when we apply a product, or change a practice, being able to answer the question, ‘What crop response do we see?’ And since the satellite has the ability to image all our fields multiple times per season, we get to follow this crop response as it progresses. This is a perspective that you just often can't get from your view on the ground.”

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Sally Krueger

Apr 24, 2019

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