Wet fall leading to dry silage?

I have been sitting on the edge of my seat waiting to get into the field to harvest my silage research plots. In late August, I noticed so many fields being harvested for silage, but then the rain started. Now, driving across the state, there are half-harvested fields and fields that were set for silage still standing.

This was particularly evident over Labor Day weekend. I noticed a chopper running, though it was probably one of their last passes as I headed into a rainstorm. Driving by that same field last week, it was still only partially harvested.

This is a hard situation many people are facing right now. The longer the crop sits in the field, the more mature the plant gets, and the drier it will be at harvest.

Why does proper moisture matter for silage?

When we make silage, we target a moisture content of roughly 60–70%, although the ideal range depends on storage:

• Upright oxygen-limiting silos: 55–60%
• Upright stave silos: 60–65%
• Bags: 60–70%
• Bunkers: 65–70%

This range strikes a good balance: proper fermentation without heating or leaching. It also helps with packing and excluding oxygen, which is invaluable to the fermentation process. Our goal is to grow lactic acid bacteria, which need an anaerobic environment. Lactic acid bacteria produce lactic acid, which drops the pH of the silage. Without that pH drop, we are at risk of undesirable bacteria taking over.

What can we do?

Many fields are probably in the situation where the crop is too dry. Dry forage is much harder to pack and to exclude oxygen from. There are a few options to work around it.

Reduce chop length and check kernel processing. The kernels will have more starch, but they are also harder at this point. Checking for good processing is essential to make sure that starch is available to the animal. Chopping finer may seem concerning from a ration standpoint, but it helps with packing density and good packing is what gives you quality silage at feedout.

Add moisture back. It takes roughly 7 gallons of water to raise moisture content 1% per ton of silage as harvested. This gets water-intensive fast. For a 10-acre field yielding 20 tons. acre at 50% moisture, that's 200 tons as harvested for the field; going to 60% would take on the ~14,000 gallons. If you have that capacity, it can work, but the dry corn needs time to absorb the water, and supplying that volume fast enough to keep up with harvest is difficult.

Blend in a wetter forage. If you have wet-harvested alfalfa, sorghum silage, or sorghum-sudangrass available, blending can help balance moisture. Getting the moisture right is tricky, and because moisture does not move easily through a silage pile, thorough mixing is important. [If harvesting a late alfalfa cutting, here are some guidelines on timing for stand persistence: Should I take a late fall alfalfa cutting?]

Pack well and seal tightly. Use heavy equipment when packing and do not pack more than 6 inches at a time. Cover tightly with plastic or an oxygen barrier to keep the environment as anaerobic as possible.

Consider an inoculant. Inoculants will not fix a moisture problem, but dry silage that is hard to pack is prone to heating at feedout. An L. buchneri product produces acetic acid that inhibits the yeasts and molds behind that heating — just plan on extending time in storage before opening, since it needs that time to work.

Give it more time in storage. This is the one adjustment that costs nothing. Bacterial activity during storage breaks down the prolamin protein matrix surrounding the starch granules, which improves ruminal starch digestibility, the same process that makes the hard, mature kernels in dry silage more available. With drier corn silage, leaning on extended storage time is a way to recover some of that energy. If you have the inventory to leave the pile closed longer, do it. This pairs well with the inoculant above; both are asking for the same thing — leave it shut.

What to expect at feedout

Even with good management, drier silage will feed differently, and it is worth flagging before you are standing at the face in January.

The fiber will be less digestible. More mature corn silage carries more NDF, and more of that fiber is lignified: which means less of it is available to the animal. Nutritionists working with dry corn silage often recommend adding nonforage digestible fiber sources such as soy hulls or corn gluten to make up the difference. This is worth raising with whoever balances your rations before you open the pile.

Watch the feedout face. A pound of dry corn silage contains more dry matter than a pound of wet silage, so the face moves more slowly through the pile — which means more oxygen exposure and more opportunity for mold and yeast growth. Keep the face fresh, remove spoiled material from the top layer and shoulders, and check that your feedout rate is keeping up.

Beyond moisture: stalk quality and contaminants

The wet conditions this fall have led to stalk quality issues and greater potential for contaminants. Watch for stalk and ear rots, which can produce mycotoxins in the silage. Fermentation does not lower toxin concentrations, and dry corn silage is especially prone to mycotoxin issues. If you suspect a problem, work with a nutritionist on whether binders or neutralizers make sense in the ration. [More information on stalk and ear rots that can cause mycotoxins: Crop Protection Network]. There are some areas with flooded ears, where ears have been submerged, this is considered adulterated by the U.S. Food and Drug Administration (FDA). [More information on submerged grain can be found: Management of Flood-submerged Grain].