John Horter, Andover, S.D., is going to be varying corn seeding and fertilizer rates again this spring.

He's varied seeding rates for a couple years on his northeast South Dakota farm.

Horter's cropland is rolling and includes highly productive low areas (when there isn't too much water) and poorer producing eroded hilltops.

He used to set his corn planter at 29,000-30,000 seeds per acre. Now's he varying seeding rate from 24,000 to 36,000 seeds per acre to better match the yield potential of different management zones he's created from satellite images and soil and yield maps. He also varies fertilizer rates by management zone.

John Horter readies his planter for another year of planting corn. He's going to vary corn seed rates according to soil productivity.

The most noticeable difference in yield and seed savings has come on the eroded hilltops, where he cut the seeding rate from 30,000 seed per acre to 24,000 seeds per acre. He says data collected by the yield monitor shows that yields have increased by 20-30 bushels per acre compared to previous years, and -- in some places -- by as much as 50 bushels per acre.

The low areas of the field, which are usually the most productive, haven't shown a clear response to the higher seeding rates. Horter says that may be because it's been so wet recently that the soil in the low areas doesn't drain adequately to maximize yields.

Horter also is using automatic row clutches on each opener to shutoff the seed when the planter reaches areas that have already been planted. It's saved him seed and yield on headlands and angle rows.

"I have a lot of angle rows with all the wetlands we farm around," he says. "It doesn't take long to pay for the row clutches."

Anthony Bjerke, president of AgTech, Webster, S.D., has been helping Horter and other northeast South Dakota corn growers with variable rate seeding and fertilizer applications.

"I'm seeing 8-10 bushels per acre increases with variable rate seeding," Bjerke says. "The biggest yield bump is coming from seeding prescriptions that are tailored to the variety being planted."