Preparing for Corn Silage Harvest

By: Dr. Jon Pretz, Dairy Nutritionist
 

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As corn silage growers near their anticipated harvest date, it’s important to walk fields to determine how the crop is progressing. Ultimately, harvest timing can be critical in achieving high-quality corn silage that delivers optimal performance for livestock. The following checklist can lead to a successful harvest.
 
  1. Optimal Dry Matter: Be ready to chop when your corn silage has reached the optimal level of dry matter to ensure proper silage fermentation and compaction. For bunkers, piles, and bags, target 32 to 35 percent dry matter.  Milk line is usually at half to three-quarter but depends on moisture in the field and drydown as milk line may not be the best indicator of when to chop.
  2. Maturity vs. Starch Level: Be aware of plant dry matter and maturity as starch levels increase. If you delay harvest to achieve higher starch levels in your corn silage, you must process corn kernels to avoid the passage of harder starch particles.  
  3. Kernel Processing: Kernel processing is crucial, especially with hybrids that have hard or dense starch forms.  All kernels should be damaged with kernels broke into four pieces or finer. Kernel size can be evaluated by one of the methods described below:
    • Take a 32-ounce cup of corn silage before ensiling and spread it out and check the processing of corn kernels.
    • Or, take two or three handfuls of corn silage, place in a 5-gallon bucket of water, skim off the floating corn plant material, pour off the water and evaluate the corn particles left in the bottom of the pan.
  4. Theoretical Length of Chop and Roller Opening: Two different equipment changes can be made: TLC (theoretical length of chop) from 3/8 to 3/4 inch and roller opening from 1 to 4 mm (millimeters). Most discussion centers on TLC while both adjustments should be considered when getting an “optimal” corn silage particle size. The following guidelines can be used and refined using a Penn State box with your local Hubbard representative.
    • Corn Silage Dry Matter, %

      TLC, inches

      Roller Opening, mm

      <33%

      3/4

      3 to 4

      34 to 37%

      3/4

      2 to 3 (hard kernel)

      34 to 37%

      1/2

      3 to 4 (soft kernel)

      >38%

      3/8

      1 to 2 (hard kernel)

      >38%

      3/8

      2 to 3 (soft kernel)

  5. Inoculant or Preservative: Always add a research-based silage inoculant or preservative.  Published research has shown a 3 percent increase in dry matter recovery and an increase of 2 percent in energy content as the fermentation is optimized. The benefit-to-cost ratio is typically 3-to-1 in nutrient recovery.  Hubbard Feeds offers both inoculant (SIL-ALL®) and preservative (BULLETPROOF®) options for your forage needs.
  6. Packing Density: Target corn silage density to exceed 15 pounds of dry matter per cubic foot in storage.  This can be a challenge for bags and drier corn silage. Packing guidelines are below:
    • Tractor weight in pounds / 800 pounds = tons per hour that can be packed correctly
    • Example: 30,000-pound tractor / 800 pounds = 37.5 tons of corn silage per hour with this tractor
  7. Cover Bunkers / Piles: Cover bunkers and piles with a layer of oxygen-barrier film and cover with overlapping plastic that lines the interior wall before covering with oxygen-barrier film.
  8. Evaluate Silage Fermentation: Check the fermentation profile of your corn silage to determine if your corn silage has an optimal fermentation pattern. Table 1 lists the desired silage pH, level of organic acids (lactic, acetic, butyric, and propionic acids), ammonia nitrogen (more important with haylage) and ethanol (not desired). Using an inoculant will enhance your fermentation profile along with optimal packing and filling rates.
    • Table 1. Recommended fermentation profile for ensiled feeds
  9. Calculate Needed Inventory: Calculate the amount of corn silage you will need for the 2016-2017 feeding year.  Be sure to have enough 2016 corn silage to reach to December of 2017.  Research has shown corn silage increases in feed value (more energy per pound of dry matter) if corn silage has been allowed to ferment for 3 to 5 months after ensiling.
  10. Calculate Corn Silage Value: Calculate the value of your corn silage at harvest time to use in your farm budgeting program. One guideline is to charge the current price of a bushel of corn grain times 6 or 8 depending on the relationship of a bushel of corn per acre compared to tons of wet corn per acre.
    • Example: 20 tons of corn silage containing 140 bushels of corn results in a factor of 7 (140 bushels / 20 tons of wet corn silage). Add the cost to harvest, transport and store silage ($5 to $8 per ton), cost of silage inoculant ($2 per ton) and shrink loss (5 percent for bags and upright silos; 10 to 15 percent for piles and bunkers depending on packing and covering.
    • Example: 2016 corn silage could be priced at $4 per bushel x 7 = $28 per wet ton + $6 harvest costs +$2 inoculant = $36 per ton + 10 percent shrink loss ($36 x 10 percent = $3.60), leading to the final value of $39.60 per wet ton.
  11. Review Your 2015 Corn Silage Harvest: Conduct a check on Item 2 (dry matter levels last year), Item 3 (processing), and Item 8 (did your 2015 corn silage ferment properly?)  If your answers are optimal, do the same thing you did last year.
Safety Message: Increased machinery traffic during the harvest season can lead to increased occurrence of accidental injury and even death around farm equipment. Remember to keep children, uninformed adults, and pets away from the machinery. 
 
Adapted from: Hutjens, M. 2015. Corn silage checklist for 2015. Progressive Dairyman. 06 August 2015