Top yields come with no-till, deep tillage Clemson University scientists combined three practices to get some eye-popping corn yield results on Coastal Plain soils. First, they used 15" rows. The other two requirements: Moisture-saving conservation tillage, especially no-till, and in-row deep tillage, such as paratilling.

A team of Clemson University and USDA-ARS scientists tested several systems for three years on the drought-prone, sandy Coastal Plain soils of South Carolina.

The result: a 26% yield increase for the best treatment compared to that traditionally used by growers in that area.

"These sandy Coastal Plain soils are very droughty to begin with, so anything you can do to enhance the soil water availability would help the narrow-row crop," explains agronomist Jim Frederick.

The system treatments for the three-year study in both the 30"- and 15"-row plots included: disked, no deep tillage; disked, deep tilled; no-till planted, no deep tillage; and no-till planted, deep tilled.

Average yields, in bushels/acre, for the four systems were:

"So our best treatment, the no surface tillage and paratilled in 15" rows, produced 140 bu/acre vs. the traditional system used here of 30" rows, disking and in-row subsoiling, which produced 111 bu/acre," says Frederick. "That's a 26% yield improvement for the best narrow-row treatment.

"We have tested this concept on large fields, too, not just in research plots," Frederick explains. "One year that best narrow-row treatment had a 75% higher yield. On a different field the next year, the advantage was 9%. There is a lot of variability, depending on the year, but it looks like the narrow-row treatment is going to be consistently better."

So how did they harvest the 15" rows without a specially designed 15"-row corn head? They used a 30" corn head, drove a little slower and took two 15" rows per snout. It worked fine, Frederick says. Farmers in that area don't raise large acreages of corn, so the slower harvesting shouldn't be a big factor.

Faster canopy closure in the narrow rows helped weed control, too. "The weed control benefits of the narrower rows were really pretty astounding," points out Frederick. "It really makes a big difference."

Does this system have broader application in the South?

Frederick thinks it might. It seems especially well-suited for herbicide-tolerant hybrids, such as Roundup Ready corn.