How to Achieve Silage Harvest Goals

Corn silage being chopped for silage.
( Rick Mooney )

Dry Matter

1. Harvest corn between 32% and 36% dry matter.

  • How to measure: Electric wood chipper and koster tester.

Action Level: Dry matter <32%: Check milk line and if milk line <75%, hold harvest one day per two points of dry matter (might vary depending on environmental conditions such as ambient humidity and temperature).

Milk Line

1. Harvest corn at 50% to 75% milk line.

Action Level:

  • Milk line: Less than 50%.
  • Wait one day for each 5% desired milk line increase after milk line appears.

NDF Digestibility

1. To improve silage digestibility:

  • Harvest plant at the desired dry matter range.
  • Plant corn as early as possible to minimize plant growth during hot weather.
  • Flood irrigation negatively affects digestibility: If possible, irrigate more often with lesser volume.
  • Do everything you can to get water to the entire field as quickly as possible.
  • Choose corn varieties that have a high fiber digestibility.

Processing Kernel And Stalk

1. Goal is to be above 70% processed grain.

Action Level: “Bucket Float Test”

  • With a 5-gal. bucket, get five handfuls of fresh corn silage into bucket, fill bucket with water, swirl and let silage settle out, scoop out what floats (stalk and leaves). Corn kernels will be at bottom of bucket. Drain water, scoop out kernels. Lay them on the ground and you should not see any whole kernels.
  • From the material that floated (stalk and leaves), observe chop length consistency and thoroughness of vertical and horizontal slicing of the stalk.
  • If you see one whole kernel or chop inconsistencies, tighten up the processor, sharpen knives, increase roller speed offset, if possible, and make sure springs holding rollers together are heavy duty.

Lactic: Acetic Ratio

1. Lactic: Acetic acid ratio of 3:1 and lots of volume of both.

2. Quick pH drop.

3. Extract as much air as possible as quickly as possible by:

  • Using the proper amount of tractor weight per ton of silage harvested per hour.
  • Tractor operator should use the reverse gear and steer as little as possible on pile.
  • Tractor operator should never stop moving.
  • Add more tractors to match rate of feed delivered to the pile.
  • For very large operations, it might help to fill more than one bag at a time, or if making a very large pile, start in the middle of the pile and continue to both ends so you can get more pack tractors packing.
  • Achieve >16 lb. per cubic foot silage pile density.

Keep Air (Oxygen) From Penetrating The Pile.

1. Air and oxygen can get into the pile in five different manners:

  • During pile building.
  • Between the time the pile is finished and time it is covered.
  • Under plastic.
  • Through plastic.
  • Directly through an open face during feed out.

2. To minimize air seepage into the pile:

  • Pack properly: Achieve <16 lb. of dry matter per cubic foot.
  • Cover the pile immediately after pile is built. Action Level: >1 hour after finish packing.
  • Place tires over the silage plastic (sidewalls OK on majority of pile, full tires or heavier weights at plastic seams). Action Level: No tire to tire contact. 
  • Use a state-of-the-art plastic cover. Action Level: No oxygen barrier technology in silage cover.
  • Build a pile that will allow feeding at least 12" across the length of the face per day, and use a defacer. Action Level: Pile wider/taller than what allows extraction of 12" across width of face.


For more on this, read Prepare Now for Corn Harvest.