Early frost has damaged many acres of corn in North Dakota. The stage of maturity of the corn and the intensity and duration of the freeze will directly impact corn grain yield. In some cases, the severity of the damage may have growers looking for options to salvage what is left of the crop.

James Rogers, North Dakota State University Extension forage crops production specialist, says that growers might consider haying their corn, but this may not be the best option for some.

Corn hay, on average, will contain approximately 8%-10% crude protein and 65% total digestible nutrients.

“The main issue with turning corn into hay,” says Rogers, “is the moisture content of the corn and getting it to dry down to a moisture point where it can be put into a bale.”

Plant maturity has a major impact on corn moisture content. The more immature the corn is at the time of frost, the higher the moisture content of the plant.

Frost-damaged corn can have a moisture content of 70%-80% and must be dried down to below 20% moisture to be suitable for baling. Ideally, the moisture content should be dried to 15% for baling. Baling at high moisture content can result in mold development, binding of protein and reduced dry matter, Rogers warns.

Another consideration with harvesting corn for hay is the potential for elevated levels of nitrate. If the corn plant was still taking up nitrates before and after frost, these will remain in the plant. Unlike silage, where nitrate levels can decrease through the ensiling process, nitrate levels do not decrease with the hay curing process. The majority of nitrates will be in the lower portion of the plant and the stalk.

“If you’re harvesting for hay, elevate the cutting height and leave as much stalk as possible,” advises Rogers.

Taller residual stalk height will reduce nitrate levels, reduce the amount of material to dry for baling and improve snow catch over the winter.

Corn stalks and cobs contain high levels of moisture, and with modern hybrids, there is a lot of plant material to handle through a harvester and baler. Rogers recommends using a mower conditioner that will crimp stalks and increase the rate of drying.

Salvaging frost-damaged corn for hay is an option, but getting the corn to dry to a moisture content suitable for baling is difficult. It can also be tough on baling equipment due to the large amount of volume and stalk material to process.

Haying corn with cobs and grain creates a bigger challenge in dry down because the grain and cob will tend to retain moisture and dry very slowly. The larger the ear, the longer the time needed to dry. This also creates an opportunity for mold to grow in ears that may be crushed or damaged during the mowing, swathing or mower-conditioner process.

Rogers offers a less expensive option to hay or ensiling frost-damaged corn: grazing it.

A big draw for farmers to graze frost-damaged corn is the large amount of nutrients recycled back to the soil, as well as ground cover remaining following grazing. If frost-damaged corn is chopped for silage or hayed, all the nutrients in the bale and organic material are removed.

Major drawbacks to grazing corn are the availability of livestock to graze the corn, fencing and water. The volume of forage biomass that corn produces can extend the grazing season significantly into the fall and early winter. Strip grazing of corn will increase forage utilization. Cattle will consume leaves and ears, and then they will consume stalks.

Be aware of plant maturity and corn ear development. Corn ears that were in the milk or dent stage at the time of frost can contain high levels of starch.

Watch for bloat or signs of acidosis if cattle are consuming large amounts of developed cobs. To manage this issue, gradually adapt cattle to grazing corn by limiting access for a couple of weeks to allow for rumen microorganisms to adjust to higher levels of starch. Cattle that have grazed on ear corn previously will preferentially and aggressively consume the ears, which can lead to acute acidosis and death. Providing several days of unlimited hay consumption can help reduce acidosis risks upon grazing a corn field.

For more information about frost damage to a variety of crops, visit NDSU’s online resource: ndsu.ag/cropfrost25.

NDSU Agriculture Communication – Sept. 12, 2025

Source: James Rogers, 701-857-7682, james.rogers.1@ndsu.edu

Source: Karl Hoppe, 701-652-2951, karl.hoppe@ndsu.edu

Editor: Dominic Erickson, 701-231-5546, dominic.erickson@ndsu.edu