An extra 4 tons of silage per acre is certainly reason enough for Gary Wilbur to continue growing narrow-row corn. Neighbor Roger Cooley feels the same way.

These Leoti, KS, growers market their silage to western Kansas feed-yards. Their switch from 30" to 15" rows came when both saw an opportunity to get more out of their land.

“I wanted to get a canopy established quicker to help decrease my dependence on cultivation and herbicides,” says Wilbur, who has grown irrigated corn and wheat more than 35 years. “I tried a half-and-half test with 15" and 30" corn to be cut for silage.”

The 15" corn yielded 33 tons per acre; the 30" corn, 29 tons per acre. That was in the late 1990s, and he's been growing narrow-row silage corn ever since.

The additional yield is from the same plant population as for 30" rows — 30,000 seeds per acre. Wilbur credits wider seed spacing and staggered plants for the stronger production.

Seeds are dropped about 1' apart in his 15" rows, compared to about 6" apart in a 30"-row program. The crop is custom-planted into wheat stubble by Cooley, who uses a 31-row John Deere MaxEmerge variable-rate planter. The planter can be converted to a 16-row planter for 30" rows.

“Planter boxes are staggered to enable seed to be planted in a zigzag pattern," says Wilbur. “No plants stand side by side with plants in the adjacent row. There is less stress on the plants, which enables plants to grow easier and perform better.”

While Wilbur depends on center-pivot irrigation in his silage operation, Cooley grows dryland corn. He plants about 18,000 seeds per acre in 15" rows.

He, too, likes the ability of 15" corn to establish a canopy faster and reduce dependence on herbicide.

“We feel we use about 25% less herbicide because of the earlier canopy,” says Cooley. “If the canopy takes care of the weeds, you don't need a long residual herbicide.”

Chris Boerboom, a University of Wisconsin weed scientist, suggests using higher seeding rates when planting narrow rows.

“Typically, on a medium-textured soil, we shoot for a harvest population of 30,000 plants on 30" rows,” says Boerboom. “If you decrease row spacing to 20" or 15" and increase plant population to 35,000, that combination really helps increase shading and reduces weeds.

“In general, it seems the potential for a yield increase in narrow rows increases the farther you go north,” he adds.

Michigan State University's Kurt Thelen compared silage yields from 30", 22" and 15" corn. Compared to the 30" rows, there was a 500-lb increase in dry weight for the 22"-row silage corn and a 1,000-lb increase for the 15" rows. That converts to overall weight of about 1,700 lbs for every 500 lbs of dry weight.

At the same time, grain yields using the same plant populations increase by about 4%.

“In one study, we compared across-the-board five different plant populations,” says Thelen. “The 4% range was consistent for all populations.

“But if you bumped up populations, you would expect to see a yield increase. As genetics continue to improve and the optimum plant population is pushed higher, you could also expect to see stronger yields with narrow-row.”

However, Boerboom warns that increasing the plant population could reduce stalk strength and cause lodging. “That is something growers have to balance in increasing their plant populations,” he says.

Boerboom also says that, even with the increased canopy, some cultivation may be needed in narrow-row corn.

“Greater crop competition from narrow rows may replace a portion of the weed control traditionally provided by cultivation. But there is not much evidence that narrow rows can completely replace cultivation,” he says. “Until more consistent and favorable results exist for weed suppression by narrow-row corn, it seems wise to either be prepared with a narrow-row cultivator or be prepared to repeat herbicide applications in years when initial herbicide treatments do not give adequate control.”

“You cannot cultivate, but there is much less need to cultivate,” says Wilbur. “We apply either Bicep or Dual and receive pretty good protection against weeds until the canopy is developed.”

Cooley chops his and Wilbur's corn with a Deere 6950 forage harvester equipped with a Kemper all-crop head.