As a former ag mechanics and ag education teacher, Don Ahrens practices what he preaches. And that's especially true with the twin-row planter he built in his shop.

“I'd read about twin-row research that had resulted in a 6-21-bu. increase and wanted to give it a try,” says the Osage, IA, grower who owns and custom farms 860 acres.

So he got to work putting his ag engineering background to use, and in 2003 pulled into the field with his shop-built twin-row planter.

It began with a single-bar Kinze 815 eight-row planter. He attached the middle bar to the back planter toolbar using two 2-ft. extensions. A third bar was added to hold the row cleaners.

Ahrens wanted to keep his 30-in. row spacing to accommodate his other equipment, so the side-by-side twin rows are 7 in. apart, with between rows at 23-in spacings. He's also added no-till coulters on the front and back to no-till soybeans into standing corn stalks.

The key to the setup was moving the center back two-row units in 3½ in. and the front two units out 3½ in. “I built it that way to get enough room to attach the tongue. Once I got those changed, I moved each row unit out 30 in. from the previous row,” Ahrens says.

“I then had to redesign the drive to get it to run the front units,” he says. “My original intention was to cut the drive speed of each unit in half since I now had two boxes for the 7-in. twin rows. I was told that this would cause the meter rpms to drop below 40, resulting in inaccurate planting. I solved the problem by cutting off every other finger in the planter unit. Now the meter could run at regular speed, planting a half rate.”

WHEN PLANTING AT a 32,000 population, Ahrens has a plant every 5.8 in. in a single row. With twin rows the plants are 11.6 in. apart. He now plants a population of 36,000-38,000 plants/acre.

“With twin rows I can get higher populations without crowding into one row,” he says. “On average I've seen a 10-15 bu./acre yield bump with twin rows. However, there have been times when I haven't seen any extra yield and times when I've had a 20-bu./acre bump.”

Although Ahrens thinks his design would work well at twice the width, or 16/32 rows, he doesn't plan to build one that wide.

Cost ran about $17,000 — the original planter at $14,000 plus the extra bar and row units at $3,000.

“I like the Kinze design because it's simple and well built. Still, it would be nice to have a center-fill unit,” Ahrens says.