Randy Price, Jimmy Flanagan, Dennis Burns and R.L. Frazier

A new device for Louisiana agriculture is unmanned aerial systems, commonly known as drones. These devices are used to obtain overhead aerial imagery of farm fields and allow farmers and consultants to gain a bird’s-eye view of a field. Small unmanned aerial vehicles provide an excellent platform for acquiring remote-sensing data for identifying problem areas in crops during the production cycle. Maps made with these data can allow a farmer to more easily see variability within a field and then take action, such as adding quarter drain ditches, applying more nutrients or noting areas for further investigation after the crop is harvested. Drones can even be used to check on cattle. Most drones used in agriculture last year were used for real-time assessment of crops and making maps.

Drones come in two types: multirotors and airplane. Multirotor drones have four to six propellers oriented upwards and fly like helicopters. Advantages of these drones are that they can take off and land vertically, which helps when obstructions are present, such as trees, power lines and ditches. Multirotor drones are also good at flying in windy conditions because they can tilt in any direction and still fly straight. Disadvantages are that they use a lot of power and can cover only 50 to 75 acres per battery charge. In addition, they are sometimes hard to see because of their small size.

Airplane-type drones are usually better for large-area evaluations of 300 acres or more but are typically more expensive than multirotor drones ($4,500 to $15,000). Newer airplane drones have nearly the same automated functions as multirotors, with automatic takeoff and landing. Still, airplane-type drones need a partially unobstructed area for landing, which can sometimes be hard to find near a farm field. Also, the imagery is often more “jittery” because the airplane twists and turns in the wind, and the cameras are usually hard-mounted to the fuselage.

Although many professional drones exist, low-cost recreational drones may provide nearly the same utility as the high-end drones. Some drones on the market can be purchase locally and sell for between $599 and $1,299. These drones are rugged and easy-to-fly and have many built-in safety features. They also have long-range transmitters that can send video several miles away.Many third-party apps allow for completely automated flights across farm fields from takeoff to landing. Near-infrared cameras are also available, but a professional may be needed mount them.

Research at the LSU AgCenter for drone use includes nitrogen-use efficiency studies, detecting pest and insect damage, and precision spot spraying. Testing is continually performed on cameras and drone equipment to quantify which perform best.

Standard drones come with an RGB camera, which delivers three basic colors (red, green and blue). NGB cameras — low-cost RGB cameras with a special filter to replace the red or blue wavelength — collect near infrared wavelengths that can be used to estimate vegetation. Still, this doesn’t mean that an RGB camera won’t see the variances that a farmer is interested in. Other research has shown that the green wavelength alone may work well to quantify insect damage.

Still, extracting and transforming the image data into meaningful information can be challenging, and many AgCenter personnel are collaborating with farmers, consultants and researchers in recording data on rice, sugarcane and soybeans in Louisiana. There is a definite learning curve with this technology, and people must be determined, deliberate and cautious in how they analyze and interpret the data. People should also note that the future use of this technology to gain useful and corrective information requires a systems approach that involves multiple steps, including data acquisition, data processing, imagery analysis and corrective action to make changes. The real challenge lies in the correct analysis and interpretation of the data.

Overhead images themselves may be a big help to farmers and consultants performing basic crop scouting. The normal view of a person on the ground does not adequately show the variability within that field. An overhead map of the field taken within 30 minutes, however, correctly shows the extent of damage and loss of yield. For this reason, basic drone operations — just getting an overhead view — may be a worthwhile endeavor.

Mapping

Going beyond basic crop scouting needs and producing maps requires specialize software and a high-end computer — gaming- or server-quality. Online services are also available and recommended in many cases. Mapped imagery is recorded straight down and is recorded at four to six acres per image because of 400-foot flying restrictions. Creating a whole-field image means assembling individual images into a large, single map typically called a mosaic. This mosaic shows see the proportionate and varying production areas and provides a much better idea of the actual variability within the field. The mosaic also can be used to construct a prescription application map, although more steps may be needed to perform this process, depending on the software used.

Cost

Table 1 lists the major components and associated costs to create a complete drone mapping package. In some situations, precision drone mapping packages with all the equipment included typically cost $8,000 to $16,000.

Table 1: Cost Associated with a Complete Drone Mapping System

Many online services that exist to make the mosaic typically cost around $100 per month, although most offer free services on a limited basis, such as several free fields per month. This may be a good option for starting out and forgoing the additional $3,000 to $8,500 cost for mapping software and a high-end computer. In addition, additional costs may be required for precision-farming software for variable-rate map production.

Current Rules

For commercial use, a license is required from the Federal Aviation Administration called a UAS “Person-in-Control” (PIC). In addition, each drone must be registered separately with the FAA. The PIC license is obtained by completing the ground school for a regular private pilot’s license and then submitting a form to the FAA. This training helps acquaint the user with the different flight zones, air space rules and standard operating procedures of manned aircraft in case you encounter one during flight. Many online courses are available for this training. Recreational flying of a drone does not require a pilot’s license, although most farm-related operation are considered commercial. A more in-depth set of rules can be found at the www.faa.gov.

Next Big Development

It’s hard to say what the next big development will be as the drone industry changes about every three months. One of the bigger developments for agriculture may be the introduction of low-cost RTK (real time kinematic) systems for less than $1,000. Several systems are currently available, although they have not found widespread use. These systems are small enough to fit on a drone and will allow the drone to do precise surveying for land leveling, measuring low areas in a field or crop height and performing precise spray operations, such as spraying levees or roadway alleys. This may also lead to the more precise application of ripeners in sugarcane, which has always been troublesome with airplanes.

Randy Price is an assistant professor at the Dean Lee Research and Extension Center in Alexandria. Jimmy Flanagan is an extension agent in St. Mary Parish; Dennis Burns is an extension agent in Tensas Parish; and R.L. Frazier is an extension agent in Madison Parish.

(This article appears in the winter 2018 issue of Louisiana Agriculture magazine.)

This is an RGB map of the rice plots at the H. Rouse Caffey Rice Research Station in Crowley. Image provided by Randy Price