False Stories About Corn Nitrates Could Kill Cattle

Nitrates unlikely to dissipate as rumors suggest. Test corn before grazing or feeding to be sure.

Published on: Aug 30, 2012

False rumors about dissipation of nitrates in corn stalks could cause beef producers to kill cattle this fall and winter.

Bruce Anderson, Extension forage specialist for the University of Nebraska, says one of those rumors circulating is that after a freeze the nitrates will leave the stalk. The claim is that it would then be safe to bale or graze corn stalks after it freezes, even if the stalks currently contain high nitrates.

Anderson says the truth is a freeze likely will have no effect on nitrate levels.

He says, "Almost all our corn plants will be mature and dead before it freezes this fall. And if some plants are still green and alive a freeze might actually cause a brief increase in nitrate levels."

Nitrates unlikely to dissipate as rumors suggest. Test corn before grazing or feeding to be sure.
Nitrates unlikely to dissipate as rumors suggest. Test corn before grazing or feeding to be sure.

Another rumor is that it is safe to graze stalks after grain harvest. In most situations they are correct but not all the time. Nitrates tend to decline as plants mature, Anderson says. Plants that produce grain tend to have lower nitrate concentrations. Also, the husks and leaves that cattle prefer only rarely have high nitrate concentrations.

"But notice that I didn't say always," he says. "I used the words tend and rarely."

He says this has been a stressful year and dryland fields still may have high nitrates, especially in the lower stalk.

You may be tempted to force animals to graze stalks a bit harder than usual this dry year when forage is short. Cattle may start out selecting safe husks and leaves but as that supply declines they will graze more of the lower stalks with potentially dangerous nitrate concentrations.

Instead, Anderson says to play it safe. Before grazing, sample your stalks. He says to check nitrates in the lower foot of the stalk. Check nitrates in the upper portion, along with leaves and husks.

"What you discover could save your animals' lives," he says.

Questions are also arising about how to feed baled corn stalks and in some cases, corn silage.

Contact local experts for help but also do an internet search for topics like "feeding baled corn" and "feeding corn silage."

There is a really nice online publication specifically on feeding baled corn from University of Tennessee Extension.

Another fairly extensive piece from the Nebraska ethanol group focuses on value, feeding and conservation issues.

A University of Illinois article gives some feeding values and suggestions for grazed and hayed corn.

A short publication from Saline County Extension in Nebraska talks about the value of corn stalks.