Online Companion: Precision Agriculture
New Technologies, Tools, and Techniques
Although this list and discussion may not have all the latest technologies and techniques, it should be good discussion starter for educators and students of precision farming. The trends discussed here in the use of these technologies has not been gathered scientifically, but these are observations and anecdotal examples from speaking with people from across the United States.
The most common use of the light bar is in row alignment. Having straighter rows allows more accurate cultivation and crop input placement and more corn per acre. Producers in the Midwest claim to be able to fit more rows in a field than in their previous plantings. Most producers with whom I have talked insist that the light bar can help them be more accurate than foam markers.
The range of accuracy within different systems can vary greatly. Deere's Greenstar with RTK provides inch accuracy; WAAS or Coast Guard correction can provide sub-meter accuracy; various other systems are somewhere in between. The less accurate systems are more commonly used in true light bars-that is, a device that provides a row of lights that indicate whether you are on your track and in a straight line with other rows. The more accurate systems are used for guidance control systems. These systems allow the tractor to steer itself in a straight row, and in my experience this does a better job than I was able to do myself.
Deere's AutoTrak system requires the use of RTK and has a new option referred to as the Terrain Compensation Module (TCM). The TCM accounts for slope and the angle that the tractor is at to determine the track of the tractor. Without this module, the slope would affect the path of the tractor more than the distance from the last track.
Several companies have developed an add-on steer assist product. These products attach to the steering column and use one or a set of padded rollers that turn the steering wheel to control steering. The steering unit interfaces with a light bar and GPS for guidance information.
Producers believe that the cost of the light bar and GPS provides savings from the accurate placement of rows. Comments from producers indicate that the savings in chemicals and seed has meant a one-year to two-year payback (see the section on on-farm research for notes on this payback data).
Variable Rate by Formula and by Remote-Sensed Data
There are services now available that will determine a variable rate fertilizer application based on remote-sensed images that measure moisture and nutrients in the soil. This is one main indication that there is a movement toward more advanced determination of fertilizer rates.
GPS Signal Accuracy
There are upcoming changes that will improve the GPS accuracy even more. New NAVSTAR Block III satellites will include an additional signal, which will be available to civilians. The L5 signal will provide users with L1/L5 receivers to be even more accurate. In addition, the European Union will soon be launching their own global satellite navigation system (Galileo), which will be compatible with GPS and improve satellite geometry.
Variable Rate in a Variety of Ways
Possibly the most unique way of using variable rate is with unmanned aerial vehicles (UAV). These are aircraft larger than remote control airplanes, similar to the drones being used by the military. They are controlled remotely from the ground, can carry approximately 200 pounds of payload, and can take off with only 500 feet of runway. This makes these vehicles useful for in-field use to remotely capture images of plant stress, process images into variable rate application maps, and control by GPS to spray only those areas that need it.
In addition there are multiple types of data to collect. Several of these devices have been around for several years, but they are gaining acceptance by the early majority. Soil conductivity is becoming a common piece of data that seems to be highly correlated with soil types and yield. It is being used to delineate management zones. Two specific devices are used to collect this information: EM38, a device that uses a laser and senses its reflectance to determine soil conductivity; and Veris, which has a set of spiked probes that also collect soil conductivity.