Bowman: Crop, stock & ledger

By DENNIS BOWMAN

For Rantoul Press

It is hard for me to believe that just a little over four years ago, I started working with unmanned aerial vehicles, or UAVs. Little did I realize how the demand for this information would consume my time, but it has been an incredibly exciting time.

Last week, I spoke at the University of Illinois Crop Science Department Agronomy Day. I drafted two of my Extension educator colleagues, Russ Higgins and Talon Becker, to help me out. The topic of our tour spot was “Drones: Improving Your Perspective.”

We started our talk with a poster showing one of the pictures that Russ had taken with his drone. It was a picturesque aerial image of a northern Illinois soybean field with a small country town and water tower in the background.

However, if you looked closely at the soybean field, you could see a dark swatch angling across the field. These darker-colored soybeans marked the impact and path of a plume of dicamba herbicide drift that had affected these nontolerant soybeans.

From the ground, you could see that the edge of the field was severely affected but not the extent of the damage. With his drone just 80 feet in the air, Russ captured an image that shows the true impact of the damage.

In my experience, that example illustrates the impact drones have on agriculture. They give us almost instant access to a perspective on our crops that we didn’t have before.

The other key points in our presentation were that drones are like tractors — they are a machine that supplies power. They need an implement attached to them to do any work. For now, the primary implements we are using are cameras, but in the future, we may see other attachments like sprayers. The drone drags the implement into the sky where we need a task accomplished.

There are a wide range of cameras available. Right now, the cameras can be divided into visual light (RGB) cameras and those that can collect wavelengths that we can’t see, like near infrared (NIR) and infrared (IR). Several years ago, NASA developed an algorithm that used measurements of NIR and red light to assess the health of plants visible on satellite imagery. This algorithm is called the normalized differential vegetative index (NDVI).

Small, lightweight, drone-sized cameras capable of collecting the wavelengths needed to calculate NDVI were hard to find in the early stages. True multispectral cameras are expensive.

The two that I have experimented with cost several thousand dollars. A lower-cost alternative was to modify a RGB camera to collect NIR wavelengths. This involves lens modifications that change the light reaching one of the channels, so instead of recording RGB (red-green-blue), it becomes NIR-G-B or R-G-NIR.

Some very interesting and useful information can be gathered with these modified cameras. However, their images can vary a lot as lighting conditions change. These cameras currently run in the $500 to $1,000 range.

For most occasional drone users, the highest return on investment is likely just a high-resolution RGB camera. These images don’t need high-end software to process, and some simple photo editing software can allow you to enhance the color variations to highlight the differences in the images.

Dennis Bowman is a crop systems educator for the University of Illinois Extension, Champaign County.

Categories (4):News, Agriculture, Columns, Opinions

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