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Timely Harvest Makes Good Corn Silage

Timely Harvest Makes Good Corn Silage

Choose the right time to harvest corn silage if you want to produce high-quality forage that will provide the best feed for livestock performance.

Selecting the right time to harvest corn silage is critical to producing high-quality forage for best livestock performance. To do that, you need to diligently monitor the moisture content.  When corn plants begin to silk you should record an expected harvest date on the calendar. "Then start walking fields and assess kernel milkline levels about four weeks after silking," advises Bill Seglar, nutritional sciences veterinarian for Pioneer Hi-Bred International. "Milkline levels provide a quick way to visually inspect the plant's maturity."

Seglar says when corn shows some dent on the ear, it's time to walk fields and find samples to achieve ideal dry matter at harvest. "To check the milkline, first break an ear in half," says Seglar. "Use the outer half of the ear."

Remove a kernel. Either bite into the tip of the kernel or poke a knife blade or pin into the bottom and push upward until the point meets resistance. The milkline is the area from the point of resistance to the crown. One-third milkline represents 68% to 72% while two-thirds milkline represents 63% to 68% moisture."

When to start sampling corn to see if it's ready for silage

Although some research suggests milkline as a weak indicator to actual dry matter, it complements lab testing. Milkline also can be used as a signal to start sampling dry-matter content levels. Dry-matter lab tests may provide the most accurate results. Seglar suggests collecting a minimum of 10 plants per field location to sample.

"Comparing a chipper-shredder lab sample to a grower's own silage samples helps build the data needed to make informed harvesting decisions," says Bill Curran, a Pioneer researcher. "Any dry-matter test is better than guessing. It's worth the extra effort to make sure farmers get the most out of their investments." 

Knowing individual field conditions and hybrid maturities also can help you choose the appropriate harvest date. Experts recommend walking fields to examine crop maturity as harvest nears, helping determine if crops are on target for the expected harvest date. Under normal conditions, the tasseling date can serve as another way to check harvest timing. "Harvest is typically six to 10 days away when the crop is about 3% to 5% wetter than optimal," Seglar says. "Yet, it's not a hard and fast rule. Outside factors such as weather and field location can affect rate of maturity and ideal moisture levels for harvesting forage."

Evaluate storage options for keeping corn silage in good shape

Growers need to evaluate on-farm storage capabilities, which can influence harvest-timing decisions, too. If you allow corn silage crops to reach 63% moisture in the field, they have the opportunity to maximize starch and tonnage yields, says Curran. Harvesting below this moisture level can lower silage quality in terms of dairy performance. 

Early-harvested corn silage will be lower in starch and higher in fiber content (neutral detergent fiber, or NDF). Hybrids with strong late-season agronomics tend to retain fiber digestibility within the 63% to 70% moisture range. 

Planting hybrids with a diversity of maturities is another way for operations with many acres to manage harvest timing. "Staggering maturities can help hit targets for field, quality or dry matter on more of a grower's acres," he says. "Consider a five- to seven-day range between hybrids to allow for a shorter or wider harvest window."

Curran says although bigger machines allow farmers to harvest in a more timely manner, there still can be limitations at the silage pit or other silage storage facility, which could allow for a slip in quality at the very end.

Summing all of this up, the key point is you can achieve high-quality corn silage by harvesting the crop at the right time. Planting hybrids of different maturities is another way to manage harvest timing. Evaluating your on-farm storage capability also helps, which influences harvest-timing decisions, too. For more harvest management tips for forage producers, visit

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