Pushing Sensors To The Next Level

Pushing Sensors To The Next Level

On-the-go crop sensor technology has been the subject of development and research for more than a decade, and for good reason. When attached to sprayers or tractor implements during field operations, the sensors have the ability to reveal crop problems and make a prescribed application in real time.


Of course, it sounds simpler in theory than it is in real life. It’s taken most of the last 10 years to get an accurate picture of what the sensor is actually telling us when it passes over a growing crop, and to build the mathematical formulas — algorithms — that turn the sensor feedback into appropriate action.

Roger Zielke, new business development manager with Ag Leader Technology, saw the potential of on-the-go sensor technology about seven years ago but wasn’t impressed enough to explore it too deeply. A few years later it was his boss, owner Al Myers, who directed him to meet with Kyle Holland of Holland Scientific about his CropCircle sensing technology. In 2008, the two companies penned a distribution agreement that would put Ag Leader’s muscle behind Holland Scientific’s crop sensor technology.

After two full seasons of promising research, Ag Leader plans to start selling the technology in early 2010 for use in a cropping regimen centered around on-the-go nitrogen application on corn.


Sensor technology works on the basis of two simple premises: The “greenness” and “biomass” of a corn plant equates to its state of health. The larger and greener the plant, the healthier it is — therefore, if the sensor can measure the plant and provide consistent and accurate data to a controller, the controller can be programmed to calculate and deliver a prescribed “treatment.” In the case of the AgLeader-Holland collaboration, the treatment will be an application of nitrogen.

Holland’s CropCircle sensor measures vegetative index data as well as basic reflectance data, which provides the information that the controller needs to decide when and how much nitrogen to apply to the corn on the go. Sensors are mounted directly onto an application rig or a tractor-pulled implement. Sensor feedback is continuous, and decisions are made by the controller virtually instantaneously.

Not unlike most variable rate technologies, the more variable the field is, the more benefit can be realized by the grower. “Anywhere you have lots of variation in soil types or fields with rolling hills and significant variations in elevation, you are going to realize the most benefit using on-the-go sensor technology,” says Zielke.

Market Challenges

One of the “tough sell” issues that Zielke sees is that the on-the-go sensor scenario requires farmers to limit pre-plant application of fertilizer so that the in-season applications can more accurately address the needs of the corn plant through the rest of the season.

Zielke says in his testing, application of N after V6 stage seems to provide the most significant benefit. “Applications made before the V6 stage are more difficult for the sensor because a small percent of the corn plant’s total N is taken up in early growth stages.”

Getting a grower to alter his long-established cropping practices is always a tall order, but a potential benefit of up to $30 per acre could serve to mitigate the tension, he notes.

Another point of reluctance is the necessity of designating a “nitrogen-rich strip” — a single application of the full rate of fertilizer that the sensor uses to calibrate itself — on each field. Zielke says that Ag Leader and Holland are working on a technology solution that could eliminate this extra step in the near future.

Despite the current challenges, the efficiency and financial benefits — along with the positive environmental message of “right place, right time, right rate” — is so far proving highly appealing to growers and application providers that Zielke is working with as testing continues throughout the Midwest.

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