Managing Drought-Stressed Crops: Best Practices for Feeding Livestock and Corn Harvesting

As drought conditions continue to stress crops, farmers need to adapt their management strategies to ensure healthy livestock and preserve feed quality. This article outlines effective methods for harvesting and feeding drought-stressed corn, soybeans, and sorghum-sudan, highlighting both the advantages and risks of each approach.

Drought Corn Management: 4 Methods of Harvesting and Feeding

There are four key methods to consider when harvesting drought-stressed corn for livestock feed:

1.  Green Chop

• Advantages
  • Provides immediate feed for dry lot or as a supplement for pasture.
• Disadvantages
  • High risk of nitrate poisoning, especially under drought stress.
  • Corn does not ferment when green chopped, nitrate levels can remain high.
    Always test nitrate levels before feeding green chopped corn!

2. Silage

• Advantages
  • Can be stored for longer periods and fed throughout the season.
  • The fermentation process can significantly reduce nitrate nitrogen content by 50% or more.
  • A great option for harvesting feed under drought conditions.
• Disadvantages
  • Drought-damaged corn may present challenges when determining moisture content for silo storage.
    • Bunker or trench silo: 65-70% moisture
    • Upright silo: 60-65% moisture
• Methods for Determining Silage Moisture Content
  • Koster moisture tester or microwave method:
    • Dry 100 grams of silage, weigh, and calculate moisture content.
  • Milk Line Method:
    • Milk line 1/3 down from the kernel crown: 68-72% moisture.
    • Milk line ½ down from the kernel crown: 63-68% moisture.
  • Grab Test (Not Recommended):
    • Squeeze a handful of silage; the moisture can be estimated based on juice released.
• Silage Management Tips for Drought Conditions
  • Test for nitrate nitrogen content before fermentation using the values in Chart 1 (included below).
  • Sample silage by collecting 3-5 handfuls from the first load each day. Keep samples refrigerated and send for lab analysis.
  • Use silage inoculants to enhance fermentation and reduce spoilage, especially under stress conditions. Ensure inoculants contain at least 100,000 lactic acid bacteria per gram of silage.

3. Haying

• Advantages
  • Provides a long-term feed source.
• Disadvantages
  • Risk of nitrate poisoning (must test for nitrates!).
  • Takes longer to cure compared to other methods.​​​​​​​
• Testing Method for Hay
  • Use a hay probe and test 25-30 samples per field, mixing them thoroughly before sending for lab analysis.
  • If corn is taken for hay before physiological maturity, allow it to cure for an extended period—approximately double the time it would take to dry alfalfa hay.
  • Haying corn after grain harvest is safer as much of the nitrate nitrogen is converted into safer forms.

4. Grazing

• Advantages
  • Excellent fall pasture and a great feed source.
• Disadvantages
  • Drought-stressed corn can result in higher nitrate levels, especially in the lower stalks.
  • Grazing should only be done after grain harvest, not prior to it.​​​​​​​​​​​​​​
• ​​​​​​​Grazing Management of Drought-Stressed Corn
  • Grazing is safer than haying since livestock typically avoid standing stalks (which tend to have higher nitrate levels). However, be sure to rotate cattle more frequently to prevent them from grazing lower, more nitrate-heavy portions of the plants.

Drought Soybean Management

For soybeans intended for forage, harvest between R6 (pod fill) and R7 (yellow pod) to ensure maximum dry matter yield. Harvesting before this stage may result in higher-quality forage but at a significant loss of dry matter.

If harvesting for soybean silage, allow the soybeans to dry to 55-65% moisture before ensiling.

Drought Management with Sorghum-Sudan

Sorghum-Sudan, another drought-tolerant forage crop, requires careful management to ensure safety and effectiveness when used for livestock feed.

• Grazing:
  • Ensure livestock are "full" before being turned into sorghum-sudan fields. Do not graze until plants reach 24 inches in height to avoid prussic acid poisoning.
  • If the plant reaches less than 24 inches before a killing frost, delay grazing for 2 weeks to reduce prussic acid risk.
• Haying:
  • Wait until sorghum-sudan reaches 36-48 inches to ensure ideal tonnage for hay.
  • If using green chop or haylage, harvest at 3 feet-early boot and only chop what can be fed within a single day to prevent spoilage.
• Prussic Acid Concerns:
  • After a killing frost, prussic acid will dissipate, so it is safe to hay sorghum-sudan as long as it is allowed to cure for at least 7 days.

Additional Notes on Drought-Exposed Pastures

Pastures that experience extreme drought and become weedy can pose significant risks. Weeds may still be green and palatable, but they could contain toxic levels of nitrates. Weeds such as pigweed, Canada thistle, lambsquarter, and nightshade are particularly dangerous to livestock when consumed in high amounts. Always monitor the condition of drought-stressed pastures carefully to minimize these risks.