The roots of strip-tilled corn extended at least 6 inches deeper than no-tilled corn 25 days after emergence (DAE) in 2009 field trials conducted by Orthman Manufacturing Co. in Nebraska.

The research examined the roots of strip-tilled and no-tilled corn at 25, 55 and 110 DAE. At 25 DAE, no-tilled corn roots extended farther laterally in the upper 6 to 8 inches of the soil profile, but the strip-tilled corn had 4 to 10 more roots.

At 55 DAE, strip-tilled corn had consistently more roots at nodes 4 and 5, had roots 20% to 36% deeper and had 18% to 33% more roots than no-tilled corn. The stalks of strip-tilled corn were slightly larger in diameter at the first internode above the soil surface than no-tilled corn.

At 110 DAE, the total soil volume of the roots in the strip-tilled corn was between 250 to 900 cubic inches more than no-tilled corn. There were 8 to 22 adventitious roots from nodes 6 to 7 on strip-tilled corn, while the no-tilled corn had 6 to 15 adventitious roots in the same area.

Roots of strip-tilled corn grew farther down into the soil than no-tilled corn, and there were more rows on the strip-tilled corn than on the no-tilled corn.

According to Mike Petersen, Orthman’s precision tillage agronomist, having 400 to 650 linear inches of roots at 25 DAE makes a huge difference for corn yields. At 55 DAE, the number of rows on ears can be determined. And at 110 DAE, corn roots reach their maximum growth, number, volume of soil explored and depth, Petersen says.

“During this root dig (at 110 DAE), we observe the fullest potential of the corn plants absorptive capacity,” he says. “Was it able to access 4,000, 6,000, 8,000 or 10,000 cubic inches of soil? For every 1,000 cubic inches of soil volume at field capacity, the plant could obtain 1 gallon of water in medium-textured soils. The more cubic inches of soil-root interface, the more nutrients are made available to the plant.”

Petersen says he typically sees 40 to 60 roots in strip-tilled corn from nodes 1 to nodes 5 and the adventitious roots.

“Big, deep and long roots tell us of a better, if not top, yield,” Petersen says. In 2005, he worked on an irrigated strip-tilled corn research project in eastern Colorado that yielded 275 bushels per acre.

“We measured 38,120 linear inches of roots below those plants,” Petersen says. “The root system bottomed out at 74 inches below the soil surface and we only irrigated with 16 inches of water.”

With more than 28 years digging pits and examining the roots of corn, Petersen says he can tell when big yields are in store.

“When corn roots exceed 10,000 linear inches in deep to very deep soils at 55 DAE, you are onto a big crop,” he says.