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More Than a Pretty Picture
Yield maps are often referred to as farmers’ report cards. Yet, those pictures can be too little, too late.
“As you go through the season, there could be things that pop up that need to be addressed immediately to reduce yield loss,” says John Gibson, a precision ag specialist with Crop Quest, Inc. “If you wait until the end of the season and look at a yield map, you won’t be able to fix anything until the following season.”
For the Kansas-based company, utilizing in-season field imagery is a proactive way to identify unfavorable situations before they do irreparable harm. “We use our program as a monitoring tool,” he says. “We look at it like crop insurance. It is good to have, but we hope we never see anything that causes us to have to fix an issue midseason.”
Crop Quest provides satellite imagery on every acre it has a crop service contract on and has grown from 30,000 unique acres to over 600,000 in the past three years. Last year alone, it processed and delivered over 3 million acres, with an average of five images per acre, of satellite imagery to its customers.
“It has been an education for our agronomists and growers,” says Gibson. “We are getting to the point where growers are starting to depend on the imagery for that full-field view.”
picking a platform
There are basically three platforms to collect imagery: satellite, unmanned aerial vehicles (UAV), and a manned aircraft. Gibson says four questions should be asked when deciding on a source.
1. What resolution will clearly show an issue in a field?
2. What will the image be used for?
3. Is timing critical?
4. What is the cost?
“Satellite imagery is the cheapest option and requires very little to get the images,” Gibson explains. “In most cases, the only advantage a UAV or airplane brings, in my opinion, is timing.”
AgPixel’s Kevin Price agrees that satellite imagery is much less expensive for mapping and monitoring large geographic areas.
“There are many valuable applications for this imagery, but field-level work has many limitations that must be considered,” he notes.
Another challenge, Price points out, is the cloud cover problem and temporal resolution.
“Landsat acquires imagery every 16 days, but if there is cloud cover over the area of interest, you have to wait another 16 days to see if it can capture a cloud-free image,” he says.
The Iowa-based company uses both UAV and manned aircraft systems to acquire, process, and analyze ag data. Working through dealers, images are often processed by the next business day.
While Price admits there is a good use for each platform, the company favors a piloted plane.
“Manned aircraft is better suited for collecting imagery at near drone spatial resolution quality, but over many thousand acres. This is a more cost-effective platform that has many of the advantages of a drone,” explains Price. “Our spatial resolution can be between ¼ inch and 12 inches, as opposed to 256 inches for satellite imagery.
“As people discover the advantages of using ultra-high resolution imagery for crop-management purposes and as the novelty of drones subsides, they will look to higher-quality imagery that can be collected and processed in a more cost-effective manner. Therefore, the use of small piloted aircraft will increase,” he says.
The cost difference between each platform can be significant, especially if a company is packaging imagery with other products associated with the data. See the illustrations above as a general guide.
“Satellites have a different pricing model than UAVs and aerial. With satellites, you can pay a flat fee for the season to get every image that is taken of your field,” says Gibson.
“If, however, the agronomist finds something of concern, you must pay an additional 75¢ per acre for a georectified NDVI (normalized difference vegetation index) map that can then be used for precision ag applications,” explains Price.
Aerial images and UAV images are typically on a pricing model that require a payment per acre per survey. “Our pricing is such that our dealers can quote the cost of flying and processing the data depending on what their costs might be. So it varies from 50¢ per acre for large acreage projects to $4 per acre for smaller ones,” says Price.
Whatever platform you settle on, both men agree what’s important is quality images and that the data is in a usable format. They say the image should be considered a clue rather than an answer.
“While in-season field imagery points out areas of variability, it’s the boots-on-the-ground walk to a specific location that reveals where the real story comes from,” Gibson says.
One of the biggest challenges, Price adds, is helping farmers understand how to interpret the images being gathered. The key to successfully utilizing imagery is partnering with an expert who can prescribe what is needed.
“Everyone asks where the value is in imagery. It comes in working with an agronomist who understands a field and can diagnose an issue based on what is being seen in an image,” Price says. “This technology enables and strengthens the agronomist’s role in a farm operation.”
justifying the cost
Spending the money on this type of technology doesn’t come easy for some.
“Two summers ago, I had a grower in Kansas who was paying for imagery on two fields right next to each other,” explains Gibson. “In a late-June image, we found a stress spot in the middle of one of his fields. At the time, there was no visible sign of stress on the corn.”
After investigating, the grower realized his well had dropped from 500 gpm to 400 gpm, and his nozzle package was blowing air in the first two towers. He was able to get a new nozzle package on the pivot to match his well output and get water to his corn in the inner two towers.
“There was a yield difference in those two towers, but catching the problem early reduced the yield loss from what could have been a complete loss,” he says. “The grower was super pleased.”
However, he was not happy about paying for imagery on his second pivot because he never had an issue the entire season.
“This is why having imagery as inexpensive as possible for monitoring problems is very important,” says Gibson. “Once an issue is found that can be addressed through a variable-rate application, you can run the numbers and see if it is economical to get a more timely or higher resolution image.”
Imagery is still considered a novelty for many growers who have not yet integrated it into their precision farming practices.
“As you begin to realize the value and return on investment through trials, I believe it will evolve into a required practice,” says Price.