Corn Stover & Silage: Maximizing Value from Corn Residues

Corn Stover: A Valuable Resource

• What is Corn Stover?
  • After harvesting grain corn, 40-50% of the plant remains in the field (leaves, stalks, husks, and cobs).
  • Provides a valuable feed resource for beef cows, stocker cattle, growing dairy cattle, and dry dairy cows.
  • Higher feed value compared to straw from small grains.
• Utilization Methods
  • Grazing: Allows livestock to consume stover directly in the field.
  • Baling: Can be conserved as dry feed in stacks or large round bales.
  • Ensiling: Preserves the stover for future feeding.
• Estimating Yield
  • Multiply grain corn yield (bu/ac) by the bushel weight of corn (56 lbs/bu).
  • Example: A 120 bu/ac crop produces ~3.3 t/ac of roughage.
  • For high-yielding fields (140+ bu/ac), a cap of 4 t/ac is typically used.
• Stocking Rate Considerations
  • Match livestock nutritional requirements with available nutrients.
  • Testing for Total Digestible Nutrients (TDN), Acid Detergent Fiber (ADF), Neutral Detergent Fiber (NDF), and Crude Protein (CP) is recommended.
  • Utilize livestock nutrient requirement tables for proper feeding.

Corn Silage: Efficient Feed Preservation

• What is Silage?
  • Feed preserved through anaerobic fermentation (acidification in the absence of oxygen).
  • Made from high-moisture crops rich in water-soluble carbohydrates (sugars).
• Key Factors for Quality Silage
  1. Particle Size: Chopping to 1/4 – 1/2 inch improves packing and bacterial activity.
  2. Moisture Content:
     • Too high: Risk of spoilage, nutrient loss, and potential freezing in winter.
     • Too low: Poor packing, aerobic fermentation, mold growth, and digestibility issues.
  3. Sugar Content: Higher sugar levels improve fermentation.
  4. Nitrate Levels:
     • High nitrates can reduce weight gain or cause toxicity.
     • Factors increasing nitrate levels:
       • Drought stress, excessive nitrogen fertilization, high plant populations, and cloudy weather.
     • Ensiling reduces nitrates by 25-65%.
  5. Buffering Capacity:
     • Corn has low buffering capacity, allowing rapid pH drop and good preservation.

Ensiling Process: How It Works

• Aerobic Phase (Initial Fermentation)
  • Oxygen is consumed by microbes, producing acetic acid, butyric acid, and alcohol.
  • Heat, CO₂, and water are byproducts.
  • Proper compaction and moisture reduce losses (target <7%).
• Anaerobic Phase (Main Fermentation)
  • Begins after ~3 days when oxygen is eliminated.
  • Lactobacilli and Streptococci dominate, producing lactic acid.
  • pH stabilizes at 4.0-4.5, preserving nutrients.
  • If pH remains high (>4.5) or oxygen enters, clostridial bacteria may spoil the silage.

Harvesting Corn for Silage

• Optimal Harvest Timing:
  • Whole plant 30-35% dry matter (DM) or 65-70% moisture.
  • Kernels should be glazed and dented, with the milk line 1/4 to 1/2 down the kernel.
• Measuring Moisture Content:
  • Microwave test: Dry a weighed sample in a microwave until stable weight is achieved.
  • Subtract final DM percentage from 100 to get moisture percentage.
• Cutting Height Considerations:
  • Standard height: 4-6 inches.
  • Raising height (e.g., 18 inches) improves quality slightly but reduces yield.

Managing Special Conditions

• Frosted Corn:
  • If only slightly frosted, DM accumulation continues—no action needed.
  • If severely frosted before maturity, delay harvest until moisture decreases.
  • If crop is at the right moisture, harvest immediately.
• Drought-Stressed Corn:
  • Net energy content often remains high.
  • Nitrate levels may be elevated—test before feeding.
  • Moisture content may be misleading—measure before ensiling.

Storage Considerations

• Choosing a Storage Method:
  • Consider cost, durability, and ease of loading/unloading.
  • Minimize oxygen exposure to reduce spoilage.
• Recommended Moisture for Different Silo Types:
  • Upright silos: 60-65%
  • Oxygen-limiting silos: 50-60%
  • Horizontal silos: 65-70%
  • Bag silos: 60-70%
• Key Strategies for Reducing Dry Matter Losses:
  1. Harvest at the right moisture level.
  2. Fill silos/bunkers quickly and compact well.
  3. Maintain a small exposed surface area.
  4. Seal storage structures properly.
  5. Minimize feed-out exposure to air.
• Managing Pile Size:
  • Remove at least 5 inches daily from the exposed face to prevent spoilage.
  • Proper face management reduces DM losses by 10 percentage points.

By optimizing corn stover utilization and silage management, farmers can enhance feed efficiency, reduce waste, and improve livestock nutrition. Implementing best practices ensures maximum yield and quality from each corn crop.