Strategies to Minimize Nitrate Levels in Stressed Corn

By Tim Stanton (Revised by Jack Whittier, Extension Beef Specialist, in 2012)
Extension Feedlot Specialist

Nitrates are of concern when harvesting drought stressed corn. One should consider the following strategies to minimize nitrate levels in stressed corn.

  1. Leave at least a 12 inch stubble at harvest. Nitrates accumulate at highest levels in the lowest portion of the stalk.
  2. Ensiling can reduce nitrate levels by about 50%. Therefore, sample silage for nitrate analysis no sooner than 21 days after ensiling.
  3. Cattle can adapt to higher nitrate levels in forages, if they are gradually introduced and "stepped-up" to higher nitrate levels by blending with low nitrate feeds.
  4. Make sure cattle have adequate vitamin A stores and feed low levels of urea with high nitrate feeds.
  5. Harvest corn at 35-40% dry matter. Check moisture since drought stressed corn is wetter than it appears.
  6. Grain generally doesn't accumulate nitrate and therefore a high concentrate diet is at low risk for creating nitrate toxicity..

The following are potentially toxic levels of nitrate:

ppm%
Nitrate50000.5
Nitrate nitrogen11500.115
Potassium nitrate81500.815

Different labs report nitrate in different forms.

Updated Tuesday, July 22, 2014