Moisture is Critical When Harvesting Silage During a Wet Year

Silage is a major component of the ration for many feedlots and dairy operations. In this photo, cattle eat silage from the bunk near Tyndall, S.D. Photo courtesy SDSU Extension

BROOKINGS, S.D. – With many flooded and saturated fields in South Dakota this fall, harvesting silage before corn dries past desired moisture levels or frost occurs may be a challenge for some producers.

“With many acres of corn planted later than average this year, there are still options for farmers who want to produce wet feed,” says Sara Bauder, SDSU Extension Agronomy Field Specialist. “Equipment availability and plant moisture should help determine what works best for an operation. If precipitation continues, famers may have to wait until freeze-up to enter some fields.”

Creating quality silage is most dependent on harvest plant moisture. Ideally, when chopping silage, the plant should be 32 to 38 percent dry matter.

“Moisture calculation is key and given the genetics of today’s corn varieties, the relationship between milk line and plant moisture content may not always be accurate,” says Tracey Erickson, SDSU Extension Dairy Field Specialist.

Harvesting at over 40 percent dry matter reduces digestibility of fiber and starch and may cause packing issues. More specifically, the optimum silage moisture ranges from 55 to 60 percent for upright oxygen-limiting silos, 60 to 65 percent for upright stave silos, 60 to 70 percent for bags, and 65 to 70 percent for bunkers.

“In other words, wetter silage tends to work better in bags, bunkers and piles for better packing. Drier silage tends to work better in upright silos to minimize seepage,” Bauder says.

An easy, quick and relatively inexpensive method to determine the actual moisture content of the whole corn plant can be performed by using a microwave oven. This typically takes less than 20 minutes to test. For step-by-step instructions on using a microwave to moisture test forages, visit the SDSU Extension website.

Chopping Dry Silage

Although not ideal for optimum feed value and storage, if a producer chooses to chop silage above 40 percent dry matter, there are several considerations to make:

Reduce chop length to release more plant fluids and improve packing.

Use a kernel processor to improve digestibility. The more mature the corn is, the less digestible it becomes.

Use silage inoculants to improve fermentation. Liquid inoculants may be more effective in dry silage.

If piling or using bunker silos, use extra heavy tractors for packing and pack no more than six inches at a time.

Blend wetter feeds with dry silage like forage sorghum, alfalfa, later-planted green corn or wet distillers grains.

Place wettest forage on the top layer of the pile or horizontal bunker for sealing and weight. Adding water to the top layer of the pile may also help with this.

Another option, although time consuming, is to mix the wetter and drier feeds in a TMR wagon prior to ensiling.

Cover tightly with silage plastic and/or oxygen barrier to keep the environment as anaerobic as possible.

“Some producers may choose to add water as they pile or fill silos, however, it takes approximately seven gallons of water for every ton of silage to raise moisture content one point and corn plant material absorbs water quite slowly. Therefore, a large amount of water would be required at a very fast rate to keep up with most silage harvest processes, making wetting nearly impossible to render major results,” Erickson says.

Chopping Earlage

With an energy content higher than corn silage but lower than corn grain, and a similar protein content to corn silage, Bauder suggests earlage as a good alternative. Ideally, moisture content for chopping earlage is 35 to 40 percent. A silage chopper with a snapper head can be used. Some producers have successfully used combines set to retain a portion of the cob with the grain. Much like silage, if harvested too wet, seepage may occur and if harvested too dry, it will not pack well which causes excessive spoilage.

Things to consider when chopping earlage:

Make sure every kernel is cracked and the cob portions are no larger than a thumbnail to improve pack density and digestibility.

Consider using a kernel processor to improve digestibility.

Use inoculants to improve fermentation.

If piling or using bunker silos, use extra heavy tractors for packing.

Cover tightly with silage plastic and/or an oxygen barrier to keep the environment as anaerobic as possible.

What to watch for

If silage is too wet when harvested, there is a risk of butyric acid forming and nutrients being lost due to seepage. Silage that is over 70 percent moisture should not be harvested and should stand in the field for a few more days. On the other hand, if it is too dry, silage will not ferment or pack adequately, resulting in mold development.

“In addition, flooded corn can contain many contaminants. Watch for corn ear molds, stalk molds and if the plant is quite dirty, soil contaminants. Preservatives and fermentation do not lower the concentration of these toxins in feed. If there are concerns or any of these issues have been discovered in the field, first consider identifying ear or stalk diseases,” Erickson says.

For more information about silage contaminants and mycotoxins, visit the SDSU Extension website

Pricing or Buying Feed

The Silage Earlage Decision Aid is available for help pricing silage or earlage in South Dakota. Alternatively, the SDSU Extension Feed & Forage Finder Facebook Page can help producers find feed for sale in their area.

“This has been a challenging year with heavy spring precipitation and now extensive fall precipitation in some parts of southeastern S.D. Remember, all hope is not lost for your silage crop; keep the options above in mind and have a safe harvest this year,” Bauder says. F

–SDSU Extension