Variable-rate planting is one aspect of precision management that is “hard to get a handle on,” says Tiptonville, Tenn., farmer Jeremy Hopper, who relies on GIS data to make many agronomic and management decisions. The interaction between population, hybrid, weather, and soil productivity is complex, and he’s not sure if variable-rate seeding will pay on his farm. The exception is in the dry corners of pivot-irrigated fields, where he usually drops the plant population by about 20%. He’s experimented with adjusting corn seeding rates by 3,000 to 10,000 seeds per acre, based on productivity zones, but hasn’t drawn any conclusions yet.

The real potential of variable-rate seeding will come when planters have the capability to vary both hybrid and population on the go, says Jeremy Wilson, technology specialist for Crop IMS, Effingham, Ill.

Keep in mind that two steps are essential for evaluating the profitability of variable-rate seeding, says Jason Hamlin, North Delta Crop Consulting, Dyersburg, Tenn. One is check strips of high and low fixed-rate populations, alongside your prescription variable-rate strips. The other is “ground truthing” actual seeding and emergence rates, Hamlin says. “A lot of people miss that step.”