No-tillers need to pay attention to the extra phosphorus, zinc and other nutrients that corn rootworm-resistant (CRW) hybrids use compared to biotech hybrids without the CRW trait, says Fred Below, University of Illinois plant physiologist.

The CRW hybrids used 14% to 27% more of five primary and secondary nutrients in Below’s 2008 research. In 2010, 47% of the estimated 87.9 million acres of U.S. corn — 41.3 million acres — were planted with CRW hybrids, according to the USDA.

Providing high-yielding, triple-stacked hybrids with the nutrients needed to maximize yields is important because seed-corn costs can exceed $120 per acre, says Dan Froehlich, agronomy director for The Mosaic Co.

Below has been comparing CRW hybrids with those without insect-resistance traits since 2006 to see if the CRW hybrids have unique nutrient requirements.

“With the CRW trait, you’ve protected the investment that the plant makes in the roots,” Below says. “Compared to hybrids without the CRW trait, CRW hybrids have more roots, which last longer.

“That allows the corn plant to be in contact with more soil and to take up more water and nutrients. There is a yield advantage by using the CRW trait because of better nutrient use, particularly nitrogen.”

Phosphorus And Zinc

What was not clear, however, was the impact of the CRW trait on removal of nutrients from the field, which ultimately need to be replenished with fertilizer, Below says.

While the CRW hybrids in the study used more of all nutrients than non-rootworm-resistant hybrids, they required…