One of the most significant changes in production agriculture over the last 25 years has been adoption of precision agriculture technology as a routine practice in raising and harvesting crops.

From early experiments with what now would be seen as rudimentary systems for yield mapping, to global positioning system technology that allows equipment to follow prescribed paths across a field, to variable rate application that adjusts seeding, pesticide, fertilizer and plant growth regulator products on the go, to the possibility of unmanned aircraft mapping fields, site-specific agriculture has come of age.

But the key to making those systems successful remains the same, says Texas AgriLife Research engineer Steve Searcy. “The challenge is to obtain information and then use it to make decisions that result in profit,” he says.

“We have the tools. We can use variable rate application to apply (specific rates) to whatever we need. The next step is to use the information to make money.”

Searcy has been involved in precision agriculture research since the mid- 1980s, taking over a project from John Schueller around 1984, after Schueller left Texas A&M and moved on to the University of Florida.

Early work focused on positioning but through microwave triangulation instead of GPS. As the Global Positioning System was increasing the number of satallites in orbit in the early 1990s, research activity was limited because not enough satellites were available to provide access all the time. “We had to do our mapping only when we knew enough satellites were available.”

Yield mapping remained the key focus into the 1990s as sensors improved, spurred by developments from Ag Leader, out of Ames, Iowa.


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“Ag Leader was the first to offer commercial yield mapping technology. Around 1993, sensors became available as third-party add-ons.” Soon, sensors became available as options on new machines as the technology became widely used. “Today, sensors come standard and a buyer might have to ask that it be removed if he doesn’t want it.” Searcy says the additional cost of a sensor is a small part of the overall cost of a combine.

Over time, as genetically engineered varieties came on and seed prices increased, producers became more interested in variable rate applications, a process that allows a grower to adjust seeding rates to field conditions without stopping to adjust planter settings. Sensors and GPS also adjust pesticide, fertilizer and other input rates on the go. “We can also switch varieties as we move across the field.”

Searcy says variable rate irrigation technology is also an option.

Cotton farmers may soon use site-specific agriculture to help solve a problem that has bedeviled the industry, in some locations, for more than a century. Cotton root rot for decades was a problem without a viable solution, causing millions of dollars in crop losses annually. Recent discovery of a product and an application technique that provides control of the devastating disease offers hope that it will no longer be an economical issue. But the product is expensive, Searcy says. “So, my colleagues are working on a site-specific technology that would allow a producer to apply the product only to areas of the field with known infestations.”

He says variable rate application of a cotton growth regulator is also possible and would be based on “how the cotton crop was growing. We’ve been working on this for a while.”