How to Harvest Silage?

Harvesting silage involves a precise sequence of steps and critical decisions, primarily focused on achieving the optimal moisture content for proper fermentation and feed quality. The best strategy often involves allowing the crop to dry down in the field, but specific conditions like frost or excessive dryness require immediate adjustments.

Key Stages of Silage Harvesting

The process of harvesting silage generally follows several key stages, each crucial for producing high-quality forage:

1. Cutting or Mowing:

   • The first step is to cut the forage crop (e.g., corn, alfalfa, grasses) using specialized equipment like mowers or mower-conditioners.
   • The cutting height is important; leaving sufficient stubble can promote regrowth and reduce soil contamination.

2. Wilting (if applicable):

   • For many crops, especially legumes and grasses, wilting is a critical step where the cut forage is left in the field to dry.
   • The best strategy is to leave the crop in the field to dry down to an acceptable level unless dry matter losses become too high. This process reduces moisture content, which is essential for proper ensiling and preventing undesirable fermentation.

3. Chopping:

   • Once the desired dry matter content is reached, a forage harvester (chopper) picks up the crop and chops it into small, uniform pieces.
   • The chop length is vital:
     • If the crop becomes too dry, consider a finer chop to improve packing density and reduce air pockets, which are detrimental to fermentation.
     • Proper chop length allows for better packing in the silo, leading to more efficient fermentation and less spoilage.

4. Transporting and Ensiling:

   • The chopped forage is then transported to the storage structure (silo, bunker, bag).
   • During silo filling, if the crop becomes too dry, consider adding water or a wet forage to achieve the ideal moisture content for fermentation.
   • Efficient packing is crucial to exclude oxygen, which is necessary for anaerobic fermentation. This is often done by driving over the forage repeatedly in bunker silos or by mechanical packing in upright silos.

5. Sealing:

   • Finally, the silo is sealed quickly to create an anaerobic environment, allowing lactic acid bacteria to ferment the sugars in the forage, preserving it.

Critical Considerations for Optimal Silage Harvesting

Making high-quality silage heavily relies on managing moisture content and responding to environmental conditions.

• Moisture Content Management:
  • The primary goal is to ensure the crop has dried down to an acceptable moisture level. Harvesting too wet leads to clostridial fermentation (butyric acid), resulting in foul-smelling, unpalatable silage with high nutrient losses. Harvesting too dry can hinder proper packing, leading to excessive oxygen entrapment, mold growth, and spoilage.
  • Ideal Dry Matter Ranges for Different Silage Types:

• Responding to Frost:

  • When a crop that is ready to be ensiled is frosted, harvest it immediately. Frost can rapidly damage plant cells, leading to moisture loss and nutrient degradation if left in the field. Immediate harvesting can salvage the quality before significant losses occur.

• Adjustments for Dry Crop:

  • If the crop dries down beyond the ideal moisture range, corrective measures are necessary to ensure good packing and fermentation.
  • Consider a finer chop: Shorter chop lengths allow for denser packing, expelling more oxygen and improving fermentation.
  • Adding water: During the filling process, water can be added to increase moisture content. This should be done carefully to ensure even distribution.
  • Adding a wet forage: Mixing the excessively dry crop with a wetter forage (e.g., fresh-cut grass) can help balance the overall moisture content.

Practical Tips for Quality Silage

• Monitor Crop Maturity: Harvest at the correct stage of maturity to maximize nutrient content and yield.
• Equipment Maintenance: Ensure all harvesting equipment (mowers, choppers, wagons) is well-maintained to prevent breakdowns and ensure efficient processing. Sharp knives on choppers are crucial for consistent chop length.
• Speed and Efficiency: Once cutting begins, aim to complete the harvest and sealing quickly to minimize exposure to oxygen and reduce field losses.
• Additives (Optional): Silage inoculants containing beneficial bacteria can be used to promote a rapid and efficient fermentation process, especially when conditions are not ideal.

Understanding these steps and critical considerations ensures the production of high-quality, palatable, and nutritious silage for livestock feed.