Production: Twin-Row Corn

Corn grain yields in a twin-row system were significantly
raised by increasing seeding rates.

By Carroll Smith

The concept of planting twin-row corn isn’t a new one. Determining what it takes to make it more profitable than planting single-row corn is the issue with which Southern corn producers are intrigued.

For several years, Dr. Wayne Ebelhar, a research scientist at the Delta Research and Extension Center in Stoneville, Miss., has worked on a twin-row corn project with farmer-cooperators George Rae Walker Jr. and his son Martin, who have farmed twin-row soybeans for about 12 years. Also participating in this endeavor are research associate Davis Clark and Extension specialist Jerry Singleton. One of the main objectives of the project was to determine the effects of seeding rates and nitrogen rates on corn production from twin-row (irrigated) plant-ings in the Mississippi Delta.

In the past, research and on-farm experience has shown that planting soybeans on twin rows usually shows a significant yield increase, so it would work well for farmers who use this system to be able to plant twin-row corn in rotation and get more use out of their machinery.

“We wanted to look at nitrogen (N) rates from 180 to 260 pounds in 40-pound increments,” Ebelhar says. “The N source was a 30-0-0-2 UAN solution with a little sulphur added and applied sidedress. The seeding rates ranged from 25,000 to 40,000 plants per acre. We used a Monosem planter and a 38-inch row pattern.”

After collecting data since 2006, the team determined that corn yields were significantly raised by increasing N rates. For example, Ebelhar notes that in 2006 the N rate averaged across all seeding rates resulted in an increase of 2.5 bu/A, which does not pay for 40 pounds of nitrogen. In fact, the yield increase did not cover the cost of the fertilizer in any of the years. On the other hand, corn grain yields were significantly raised by increasing seeding rates, with the highest yields obtained using a seeding rate at or above 40,000 plants/acre.

The data also show no statistical interaction between seeding rates and N rates, and harvest moisture was higher with the higher seeding rates and higher N rates.

Farmer-Cooperator Weighs In
George Rae Walker, Jr., the farmer cooperator, says they use 38-inch rows on the farm so they can furrow-irrigate their twin-row soybeans. His preferred crop mix is a 50-50 soybean and corn rotation. One of the reasons for his interest in twin-row corn is to get the most use out of his Monosem planter.

“We want twin-row corn to work out so we can do everything the same way.”

Also, based on his experience, Walker says it’s important to get the row flat and firm, so the twin-row corn will “stay on its feet.” He sets up his beds the previous year, then knocks them down early and waits for another rain, hopefully to create a firm, flat surface on which to plant the corn.

He says it’s also important to plant the corn seed at least two inches deep.

“If you don’t,” Walker explains, “the birds will pull it up, or a freeze can easily kill it.”

The farmer cooperator continues, “We believe we can plant 4,000 to 5,000 more plants per acre (for a total of 36,000 plants/acre) than we can with single-row corn and still have very little lodging. The stalk strength of a hybrid also is important to our operation because of the threat of hurricanes or other instances of bad weather. However, I do like to spread out my risk by planting different hybrids.”