Stine^® FieldMax system: Four one-of-a-kind harvesters, three decades of innovation

ADEL, Iowa (Oct. 15, 2026) — Stine^® Seed Company harvests its seed corn with four custom-built combines that exist nowhere else. Designed and refined on the Stine Seed Farm for three decades, the machines make up the Stine FieldMax Seed Corn Harvesting System.

“There are only four machines like it in the entire world, and they’re all right here on our farm in Adel,” says Steve Luther, Stine Seed Farm manager. “We’ve built all these machines ourselves.”

A FieldMax harvester does a job a grain combine cannot do. A commercial combine shells corn in the field. A seed corn harvester has to bring the ear in whole and keep the germ intact, because the corn will be planted as seed rather than sold as grain. Each FieldMax machine husks ears in the field, sorts them onboard and delivers them whole to drying boxes, so the seed passes through Stine’s hands only once between the stalk and the dryer. 

Three decades of rebuilding the same idea
The first version was built on a John Deere 7700 in 1996. Luther’s team moved to 8820 platforms next, mounting two husking beds on board, then needed more hydraulic capacity, more horsepower and more room for crop flow. That led to the John Deere 9860, which offered a larger frame the team could stretch further. All four FieldMax combines have run on that base since 2016, and each one is roughly 4 feet longer and 4 feet wider than the machines Stine started with.

“Every time that we had a new idea and a change coming, it meant the machine had to get bigger,” Luther says.

Volume came first, speed followed
The early machines bottlenecked the crop. Ears bunched up in conveyors sized for a smaller machine, and bunching is what damages them. Widening and lengthening cleared the bottleneck, which improved how the crop came through and, as a byproduct, how fast the machines could go. Early versions ran 1 mph. Today they run 2.5 to 3 mph with 30-foot heads, and each harvester covers 40 to 45 acres a day.

“Our biggest improvements on these machines have been really just the volume that goes through it,” Luther says. “As we made these machines longer and wider, we had the ability to move more volume through these machines, which brought up ground speed.”

Engineered to handle the crop gently
The feeder house comes off a standard Oxbo seed corn harvester, the kind used across the industry, with a belt conveyor in place of a feeder chain so grain is not damaged on the way in. The farm upfitted all four within the last five years and rebuilt everything under the cab to accommodate it.

The corn heads run on hydraulic drive, controlled from the cab with a hydro lever that moves them forward or in reverse at much slower speeds. Because the machines are longer, the heads are heavier, so Luther’s team doubled the lift cylinders from two to four. Leveling systems on the rear axle hold the husking beds evenly full across hills and valleys.

Husked in the field, handled once
Ears leave the feeder house on a long belt, split by diverters between two sets of husking beds, then travel by conveyor to a sorting deck where the crew of 10-12 people pull off-types and unhusked ears. Rejected ears return for another pass. Everything else exits a side conveyor into aerated boxes that stack on the farm’s dryer plenums.

“It’s a three-step process,” Luther says. “That gives the grower a better product and less damaged grain. … It is proven over the years that we have better germination because of it. These machines are very large, and they’re very capturing. They work in an entirely different way, and in the end, we’ve really got a machine that’s very efficient and very reliable.”

Drying stays small-batch. Each station holds four boxes at roughly 125 bushels of wet ear corn apiece, with one large fan moving high volumes of air at low heat, and corn dries in two to three days.

A harvest mapped before planting
Timing matters as much as the equipment. Planning for the next harvest starts as soon as the current one ends.

“Harvest timelines are mapped before planting even happens, and we base them on hybrid and variety maturity,” Luther says. “Being proactive helps us maintain a season-ahead approach, leading to a more efficient harvest.”

This planning covers roughly 10,500 acres of corn and 10,100 acres of soybeans on the Stine Seed Farm. The corn divides into 1,850 acres of seed corn and 8,650 acres of field corn, and the full season runs 10 to 12 weeks. The 2026 harvest began Aug. 18.

A strong start
“As of today, we are very pleased with what we have harvested, both in our seed corn and early field corn,” Luther says. “We’re seeing good yields and very good plant health.”

“One thing I’ve learned at Stine is the value of innovation,” Luther says. “Whether it’s the equipment or the way we produce seed corn and soybeans, we’re always innovating.”

See the FieldMax system at work in the video on the Ask the Agronomist blog. Farmers can also contact their local Stine sales representative for more details on Stine seed corn.