Spotlight on Economics: Procuring a drone not for the faint of heart

Cheryl Wachenheim Professor
NDSU Agribusiness and Applied Economics Department

“I sure hope I get a drone for Christmas,” my son said as though he simply was making an observation.

After many years of motherhood, I am quite skilled at ignoring statements made to no one in particular; and this was my strategy. We have dozens of “have to haves” that still occupy a storage bin in the hopes my grandchildren will have more use for the toys than their parents.

After he became a bit less subtle, I asked him, “What are you going to do with it?” He started to respond but quickly paused when he realized he had not thought beyond the purchase point.

I knew in my heart he could have told me he was going to put the drone on the shelf and look at it, and it would make the list if for no other reason than to see the joy on his face Christmas morning. Knowing the purchase was inevitable, I moved through the due diligence process of reading reviews and trying to sort out those credible from those perhaps with a hint of bias.

During the process, I came across several reviews about drones for use in agriculture. I was amazed at the number of factors that go into the decision, even for those concerned primarily with imagery. Although the value of different features is operation-specific, product reviews can be very helpful in that they identify what those features are; that is, what we need to investigate when considering a purchase for the operation.

One feature, which will limit the number of options, is whether you are interested in a fixed-wing or rotary aircraft.

Fixed-wing are touted as the best choice when you have a lot of ground to cover because they are substantially faster than their rotary-winged counterparts. The associated disadvantage is that the trade-off for speed is generally image quality. For example, fixed-wing drones may not be able to capture survey-grade and three-dimensional topographic detail.

Drones have plenty of other features to consider. In the interest of avoiding the tedium associated with reading a list of features, I offer the following review, compiled as a collage of fixed-wing aircraft reviews. For good measure, I include some basic definition or explanatory information. I cover them as ready-to-fly, including hardware, software and sensors.

The first is a $16,000 fixed-wing drone package that includes software designed to work within a complete drone-to-tractor workflow. It is easy to fly, with automated flight planning as simple as uploading field boundaries from the commercial farm management information system you already are using or drawing field boundaries on a map on the screen. It has one-button launch and is automatically self-landing.

It provides real-time information about the current flight and remaining battery life, reacts to changes in weather conditions and payload, is durable, has good stability, and weighs in at 4 pounds, with the ability to carry another 3 pounds.

This drone is fast and can capture multispectral and visual data on more than 400 acres on a single charge, which lasts about an hour. A standard camera provides images that are relatively easy to interpret visually but are condition-dependent. In other words, the resulting imagery only can be compared accurately with images taken in the same general area under the same conditions.

This is not the case for the included multispectral camera, which will capture images reflecting absolute plant health, or images that can be compared across time and between fields in different locations.

The drone includes a wide range of sensors to capture visual, thermal/infrared multispectral, light detection and ranging (LIDAR, a sensor-based survey method useful to create 3-D images) and hyperspectral (very narrow band) data. It uses sensors to measure humidity, temperature, air pressure and light. Changing a sensor is easy (plug and play).

Data captured from this drone can be processed using any popular software. It is compatible with open-source software so it can be adapted to specific conditions and uses. Or, as part of the package, you can purchase software that can be used to process your data.

Available indices include plant height, plant count, enhanced normalized difference vegetation index (NDVI, used to measure plant health), field uniformity, volume measurement, optimized soil-adjusted vegetation index (which overcomes the soil background sensitivity associated with NDVI) and water pooling. Index maps can be used to generate prescription maps, again using your choice of software or the system’s optional mapping package, and can be uploaded into a farm management information system or to farm machinery. It is quite an impressive drone.

Switching focus to rotary drones provides allowances of lower altitude scouting, spotting and detailed surveying tasks. Rotary drones provide more control over imagery, providing higher accuracy and resolution. Limitations include less range and less flight coverage, generally less than 50 acres per flight, although limited range is a less important disadvantage under current line-of-sight rules.

I include two reviews so as not to set an expected price benchmark because you will find the price extremes in rotary drones can be high.

The $1,500 starter-level rotary package includes a camera with a visual sensor. Software is included for image processing and mobile-ready in-flight control. The drone is good for visual surveys but lacks the multispectral camera that provides data for NDVI. Basic image processing software is limited to a one-year subscription. You can download on-site software updates, and you can use an off-market camera without voiding the warranty.

The $7,000 package is good for larger-acreage coverage uses. It uses multispectral imagery with two on-board sensors (visible and NDVI) installed. The package comes with excellent data-mapping software and offers the ability to live-stream NDVI crop data, although compatibility with other information management systems is somewhat limited. The drone can be controlled by a smartphone. Images are geotagged or time-stamped.

The three examples provide a lot of insight about available characteristics. Criteria I want to highlight are capabilities associated with automation and manual override; any warranty-voiding actions; and system flexibility, including updates and external hardware, and software use.

The latter can be particularly important, and increasingly so. Even if the system comes with proprietary software that meets your current needs, as the technology quickly evolves, what seems to fit your objectives now may not in the near future.

Making sense of the options is not for the faint of heart. Many drone models are available, and the list of credible full-service drone packages with data management services is growing. If you do decide to purchase a system, consider requesting on-site operating instructions and practice.

The instruction book or training manual should be more than a reference; it should serve as a learning guide that will help reveal the capabilities of the technology and how they apply to your individual operation. Unless used for agritourism, photography or similar purposes, the drone is only of value if the information can improve decision-making.

Finally, consider that leasing is an option, especially for nonrecurring decisions, and can be helpful as a precursor to investment, even for operational needs. It can help you learn what you find of value, thereby helping you refine your search criteria for the equipment and data management service.

My own automated return-home capability requirement for my son’s drone cut the options down considerably but will provide considerable peace of mind for his mother.