“Rattle! Clank! Whomp!”

There’s quite a racket coming from Gary Dierks’ newly planted soybean field. It’s the sound of rocks and corn root balls being pushed down into the soil by a 50-ft. Degelman land roller sweeping over the field.

Land rolling is catching on with Upper Midwest soybean growers. The practice began in Canada, gained steam in North Dakota and northwestern Minnesota, where it has become routine, and now is spreading like crazy in southern Minnesota and Iowa.

Land rolling prepares fields for harvesting by pushing down rocks, flattening residue and leveling the ground. Proponents say rolling also makes combining beans faster, easier and less tiring. There’s less chance of picking up rocks or big corn root clumps, which can damage guards, sickle sections or expensive internal combine parts. “Farmers really like it,” says John Holmes, Iowa State University (ISU) Extension field agronomist.

Despite the growing popularity of land rolling, though, few Extension experts are ready to give it an unqualified endorsement. “This concept is new and not yet well tested in the field,” says Mahdi Al-Kaisi, ISU Extension soil scientist. Among his concerns: greater potential for soil compaction, surface runoff and soil erosion, as well as questionable economic return.

Gary Dierks, Chokio, MN, farms highly productive silt loam soils studded with rocks left behind by glaciers. For the last five years, he's paid the local co-op $5.50/acre to roll his soybean fields immediately after planting.

Rolling is a useful harvest aid, he says. “Since I started rolling, I’ve never broken a sickle section,” a mishap that used to often slow him down. “You get a cleaner cut, too, because the cutter bar isn’t bouncing around so much. It glides across the field.” And there’s a lot less soil in the grain tank, he adds.

Although some people claim that rolling soybeans increases yields, “we haven’t seen that,” Dierks says. He did on-farm strip trials to test rolling, and “there was no yield difference.” Recent research in North Dakota, Minnesota and Iowa confirms Dierks’ observations, finding no yield gains from rolling. The biggest advantage, Dierks says, “is peace of mind.”

Gary Naeve, a farmer and president of Custom Made Products in Humboldt, IA, is one of the largest Midwest land-roller dealers. He rolled his own soybean fields for the first time in 2004 and was an instant believer. His neighbors were curious about what he was doing, and before long he was leasing and selling the big rollers. He's sold over 200 of them; and last season he had 40 machines out smoothing Iowa soybean fields.

“If you once roll beans, you won’t want to plant again without it,” Naeve says. Seed bean buyers “love the rollers,” too, he adds, because rolling “eliminates dirt in the seeds.” Ditto for custom combiners, who can harvest rolled fields faster. Insurance companies like them, he says, because claims for combine damage drop.

Does the practice put money on growers’ bottom lines?

“That’s not the real issue,” Naeve says. “The real payback is that you can combine with no interruption for maintenance, no dirt in the beans and less downtime for repairs.” If your beans are ready, you can get into a rolled field even if the ground is wet, he says. And there’s less operator stress and fatigue, he says – a benefit that’s hard to put a dollar value on.