After 30 years, Arlen Koepp knew his western Minnesota soils like the back of his hand. What he didn't know was exactly what to do to start squeaking every last bushel from every last acre.

So two years ago he met with crop consultants Darren Johnson and Frenchy Bellicot, and University of Minnesota specialists to figure out ways to bump his yields to the next level. That step meant a move to narrow rows and changing seed varieties on the go to accommodate the varying soils on his rolling hills near Boyd, MN. And since he'd mapped his soils, he was already a step ahead.

“It's a whole new way of looking at ground,” says Koepp, who grows about 750 acres of beans and 750 acres of corn. “But whatever I do, it has to pay for itself.”

To begin, he modified his 8-row, 36-in. Kinze double-bar, plateless planter into an 18-row, 22-in planter. “I bought 10 additional planter units to hang on the bar at $200 each. And, I extended the toolbar 4½ ft. on each end with 7-in. × 7-in. steel tubing. I then reinforced the outer third of the toolbar with additional 4-in. × 4-in. tubing.”

He also bought an old anhydrous cart and Gandy air box for about $3,500. He then mounted the 60-bu. hopper on top of the cart and welded a 1/8 in. steel plate inside the hopper to split it into two compartments. Half is used for one seed variety, half for another.

He then attached 18 1-in. hoses (36 total) to each side of the Gandy box and also to the planter seed unit. That completed, he's now able to switch varieties from either bin in the hopper box. In total, he used 1,000 ft. of hose at a cost of $1/ft.

Inside the tractor he uses his color-coded soil sample charts, fed into the computer, to determine what varieties to plant where. He pre-selects the top two varieties that fit the area he's seeding and fills the bins with them.

“If more than half the color chart shows up in red, the whole width of the planter switches to a different variety,” Koepp says. “If more than half is blue, it switches to the other seed variety in the Gandy box.”

So far, he's only able to switch the whole width of the planter at once. He's unable to move from bin one to bin two with individual planter units. That's next.

“On beans, blue generally means I'm on higher, better ground. Red means low, poorer soil because it's higher in alkali and salts,” Koepp explains.

Although varieties change automatically based on the soil charts read by his iPAC pocket PC and GPS system, he has to manually change the plant population. On the Gandy box, a Raven control unit monitors the motor to tell it how fast the planter population should run.

“On some areas I know the soil will produce so I bump up the plant population manually from inside the cab,” he says. “Right now I've programmed only two settings, either 160,000 seeds/acre or 210,000 seeds/acre.

“I think this same idea could eventually work with corn, too. But I'll have to modify my planter when I get to that point,” he says. “First, I need to be more accurate with metering.”

Koepp's convinced the system paid for itself this year alone. “By planting the right variety in the right ground, we were getting a five to 10 bu./acre yield improvement.”

Costs for his new setup have been minimal, about $5,000, not including his GPS system. And even though he says the system is working pretty well now, he figures it still will take a few years to capture every last bushel from his soils.