VIRTUALLY ALL farmers in the Midwest now have access to networks that can be tapped for high-accuracy guidance on machinery. The universal access comes from real-time kinematic (RTK) correction networks operated by state departments of transportation (DOTs), as well as Trimble and Leica.

Until the advent of these multipurpose systems — generally referred to by the acronym CORS, which stands for Continuously Operating Reference Station — access to RTK correction signals depended on whether a farming operation fell within the boundaries of a dedicated ag RTK network. These radio-based networks often are operated by farm machinery dealerships and typically serve guidance systems from specific brands, including AutoFarm, John Deere and Trimble. Setting up your own RTK base station system was a pricier alternative.

“The reality is that CORS RTK makes RTK accessible to an exponentially larger group of farmers than radio-based delivery across the Midwest,” says Matt Darr, Iowa State University. “These networks provide access as never seen before in U.S. agriculture.”

Dedicated ag RTK networks will coexist with CORS networks, Darr predicts. The radio-based ag networks will have an advantage in areas with poor cellular coverage, because the CORS networks deliver correction signals via the Internet using cellular networks, he explains.

Statewide DOT CORS networks currently are available in Iowa, Indiana, Ohio, Michigan, Minnesota and Missouri. In Wisconsin, a CORS system will blanket the state by 2011. Privately owned networks cover eastern Nebraska (co-owned by Leica) and southern Illinois and east-central Iowa (operated by Trimble under its VRS Now brand). — David Hest

For more details on CORS and dealer-based RTK networks, visit — David Hest