Nitrates are of concern when harvesting drought stressed corn. You should consider the following strategies to minimize nitrate levels in stressed corn
- Leave at least a 12 inch stubble at harvest. Nitrates accumulate at highest levels in the lowest portion of the stalk.
- Ensiling can reduce nitrate levels by about 50%. Therefore, sample silage for nitrate analysis no sooner than 21 days after ensiling.
- 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.
- Make sure cattle have adequate vitamin A stores and feed low levels of urea with high nitrate feeds.
- Harvest corn at 35-40% dry matter. Check moisture since drought stressed corn is wetter than it appears.
- 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
Chemical | ppm | Percent |
Nitrate | 5000 | 0.5 |
Nitrate nitrogen | 1150 | 0.115 |
Potassium nitrate | 8150 | 0.815 |
*Different labs report nitrate in different forms