So far, the corn looks great, but can I tell you something? The thumb rule for chopping corn silage is approximately 50 days after tasseling. For the corn that tasseled around the Fourth of July, that means the corn could be ready for chopping around August 23! At the very least, it’s probably worth a walk through the corn-especially the earliest tasseling varieties, to see how the cobs and corn is maturing. In addition, let’s talk a little about the corn silage harvest itself.

On a lot of farms, corn silage has become our most important crop. It really pays to try harvest and store it the best that we can. Here are a few tips for putting up good corn silage:

1. Put it up at the right moisture

So critical for corn silage quality, but so difficult to judge.

If you’re filling a silo, you want around 60% moisture. In bags or bunkers-65% is the moisture that works best.

Look for milk line at about 1/3 milk line-moisture at this point is most often around 70-72%. 

Better yet, chop a few stalks and dry them down for a more accurate reading.

2. Set the length of chop

The length of chop depends on a couple of things. First, if the corn silage is unprocessed, you want the length of chop to be a little finer-around 3/8 to 1/2 inch so that you break up some more kernels and it ferments better. If the corn silage is processed, you can add a little more length-about 1/2-3/4 inches.
Secondly, it depends on the amount you plan to use in the diet, especially if you don’t process your corn silage. If unprocessed and you’re sure you won’t be using more than 1/3 of the forage needs from the corn silage-you can go even finer.
Finally, make sure the knives are sharp. Tearing and uneven chopping can result in more mold and yeast growth-and poor packing.

3. Process the kernels

A lot of corn varieties on the market have pretty hard and dense kernels, so processing makes a lot of sense.
All kernels should show breakage with most broke into 4 pieces or finer.
To optimize both starch digestion and chop length, the recommendation is to set the chop to 0.75 inches length and initial roller clearance to .12 inches (1-4 mm). 

4. Pack tightly  & cover

If you are putting the crop in a bunker or pile, the packing density is really important for good fermentation. Shoot for density to exceed 15 pounds of dry matter per cubic foot.
To do that, calculate the tractor weight in pounds divided by 800 pounds. That equals the number of tons of corn silage that tractor can pack in an hour.
For example: a 30,000 pound tractor divided by 800 pounds = 37.5 tons of corn silage per hour that this tractor can pack-to arrive at a good packing density. Now just to figure how much the chopper box or truck holds…
Finally, cover it. The better the job of covering the corn silage, the less air that it gets exposed to-the lower the chance of spoilage, molds and yeast. Without a cover, shrink or loss can be as high as 20%.

5.Use innoculants or perservatives

In a perfect year, corn silage at the right moisture, has enough natural fermentation that innoculants are typically not needed. BUT when was the last time we had a perfect year? Or the perfect crop? Innoculants and preservatives are just good insurance.
Which one should you use? Depends. Normal lactobacillus types of innoculants work best in most cases. If you don’t have a good facer or if you have a silo that may have some small leaks, you might want to try an innoculant with L. Buchneri which helps reduce wild yeast growth at feedout. Finally, if there is any visible mold on the crop or it was damaged by hail-use the preservatives.

And just a final note. If you can wait to feed it, wait. Best case scenario is that it is fully fermented-about four months. If you need to feed it sooner, try and wait until at least 3 weeks after fill-the unfermented sugars in the silage can make the cows gassy and go off feed.