Online Companion: Precision Agriculture

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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.

Guidance Systems

The light bar or parallel tracking is surprisingly one of the most popular current trends. What was once a speculative use of precision technologies has become a valuable tool for producers. Producers and students with whom I talk insist that the light bars and parallel tracking are more accurate than foam markers and one of the first precision farming tools that they have purchased. It does appear that a large percent of family farms have purchased a light bar before a yield monitor.


The hands-off approach to driving a tractor helps reduce fatigue, allows the farmer to pay attention to the crop and implement, and increases the accuracy of row spacing. (Courtesy of Deere & Company)

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 straight rows allow centralized compaction (only in certain wheel tracks), thus reducing it overall in the field. (Courtesy of U.S. Department of Agriculture, Agricultural Research Service)

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.


Automatic steering can now be added to a tractor without major mechanical work. This unit attaches to the steering column and controls the steering wheel for you. (Courtesy of Ag Leader)

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

A standard formula to calculate fertilizer nutrient application has included current level of that nutrient (as determined by a soil test) and yield goal. Several research studies are being directed at determining whether this, because of the interrelationships in soil nutrients, is the best model to determine the amount of fertilizer. Factors such as pH, CEC, and moisture also impact the level of nutrient that is available in the soil, yet the standard formula does not take this into account.

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

In the early 1990s when GPS came out, inaccuracies of 300 feet were common and differential correction was necessary. As more NAVSTAR GPS satellites were launched, accuracies increased. When Selective Availability was turned off, a tenfold improvement of accuracy was seen. More differential correction towers and WAAS made free signal accuracies even better.


The newest GPS NAVSTAR satellites will have additional frequencies, which will improve accuracy for civilian users.

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

Most producers are innovative in their ideas-given a tool, they can come up with more than the intended way to utilize it. Variable rate, originally used for fertilizer application on large custom applicators, is being used in other situations. Side dressing fertilizer, foliar application, manure application, and in combination with on-the-go soil monitoring equipment are a few of the ways in which variable rate can be utilized.

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.


This drawing of a UAV drone used by the military can carry over 200 pounds. A vehicle such as this could carry a chemical tank and spraying boom. (Courtesy of the UAV Forum)

Data Collection

GPS units are getting smaller, more compact, and more integrated. GPS can now be connected to handheld computers through compact flash ports, secure digital ports, or even wirelessly. Tablet computers, hardened covers, or handheld computer devices come with data collection software. Wireless connections to the Internet in the field allow real-time download of aerial images or other data. This all increases the ease of use and robustness desired by the early majority.


A wireless GPS unit provides even more flexibility and ease of use in collecting spatial data. (Courtesy of Semsons & Co. Inc.)

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.


Being dragged behind an ATV, the EM38 collects soil conductivity data.


This Veris unit is also collecting soil conductivity with a different technique. (Courtesy of U.S. Department of Agriculture, Agricultural Research Service)

Sensor Web

One of the most exciting new technologies that is being applied not only to agriculture but also to many other industries is a sensor web. As the name implies, it consists of a group of wirelessly connected sensors that form a web throughout an area of interest. The sensors can be programmed to collect humidity, temperature, or other environmental attributes. With each sensor spatially identified, data collected from each can be used in a GIS to analyze field conditions. Current webs deployed in vineyards or horticulture allow managers to determine proper irrigation rates or harvest dates.


This is a sensor pod, one unit within a wirelessly connected web. (Courtesy of U.S. Department of Agriculture, NRCS)


This sensor pod is collecting temperature and humidity data from this localized area of a lettuce field. (Courtesy of U.S. Department of Agriculture, NRCS)



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