Test for Nitrates in Drought-Damaged Corn

As the extremely hot and dry growing conditions continue to take their toll on the 2012 crop, Midwest farmers are considering options for drought-damaged corn. More and more corn acres being chopped while there is some feed value to capture.

If you’re planning to use drought-stress corn for forage, here are some important tips to keep in mind:

  • Drought stressed corn silage, green-chopped forage can cause nitrate poisoning.
  • Nitrate levels will be highest in fields that received high levels of nitrogen fertilizer or manure applications.
  • Nitrate levels are highest in the bottom of the stalk and less in the top of the stalk and in leaves. Harvest only the upper two-thirds of the plant to reduce the potential for nitrate toxicity.
  • Test drought-damaged corn that you plan to green-chop prior to harvest. Limit the amount fed and introduce it slowly.
  • Ensiling the crop decreases nitrate levels. Do not feed for a minimum of a month after ensiling, and test them for nitrate levels prior to feeding. CAUTION: excessive nitrate silage produces gas that is hazardous to people and animals. Do not enter the silo without thorough ventilation and ventilate the silo chute to the outside. Be cautious around bunkers and piles.

Harvesting drought corn silage is difficult as the field varies so greatly. Some plants may have died while others still alive. That’s why it’s so important to take a representative sample. The moisture goal is 65 to 70% whole-plant moisture. That will be difficult to achieve if some leaves are dead and dry. If the forage is too dry, water could be added to aid with packing. While adding water is not ideal, adding about 4 to 7 gallons of water per ton of forage for every 1% increase desire in whole plant moisture. Moisture will help with packing, and packing is crucial for good fermentation. Fermentation is also critical to help reduce nitrate levels.

Remember to test and retest to verify actual levels. Testing before feeding is critical.