Satellite imagery also helps gauge productivity. “Satellite images are taken during peak crop growth periods,” Popp said. “Imagery measures biomass; high biomass equals higher yield potential. It’s a good tool to use to jump start grid sampling and variable rate fertilizer application.”

Producers should use yield histories, yield maps and satellite imagery to identify “consistent management zones — areas where yields are consistently high or consistently low. Farmers should spend time on the consistent areas, not the random ones they can’t control.”

With enough data, farmers can begin managing those zones based on yield potential. “Zones with high potential get more inputs; zones with low potential get less. Typically, we over-fertilize low yield zones and under-fertilize those with high production potential.”

Popp said fertilizer is rarely the limiting factor in crop yields. Before increased fertility will help low-potential zones, producers must fix the underlying problems. Those could include low pH, compaction or erosion, among other possibilities.

He recommends farmers plant “test strips to verify productivity. And document everything.”

Potential to improve efficiency and increase profit potential with variable rate technology is significant. But farmers face some serious challenges to make it work. “Time is a factor,” he said. “It takes time to create maps and develop prescriptions for fields.”

Calibrating equipment is also a critical factor. Yield monitors, as well as application equipment, must be calibrated precisely. “Often, farmers just have to make the time to do these things.”

Computer issues also pose challenges. “Sometimes they crash,” he said. “And yield monitors may malfunction. Human error is also a distinct possibility, so write down everything.”

Yield monitors, especially for cotton, have been inconsistent, Popp said. Cotton yield monitors may be especially erratic during periods of high humidity, when yields will be off a bit. “Always make a note of conditions.”

Weather, as with all other aspects of farming, affects variable rate technology.

Even with the challenges, Popp envisions a future in which more and more farmers will adopt the practices that will help them manage costly inputs.

“Information will be more detailed, more representative and based on environmental conditions,” he said.

Farmers will continue to face huge risks and narrow profit margins, but as technology continues to advance they will have better and better tools to identify problem areas and productive spots within fields. And that will allow them to manage those risks with a bit more confidence.

rsmithg@farmpress.com