By Scout Nelson
Volunteer corn is a common challenge for farmers, especially after dry growing seasons. Drought can weaken corn stalks, causing plants to fall over and ears to drop before or during harvest.
These dropped ears may produce volunteer corn in the next growing season. Volunteer corn can compete with crops for water, nutrients, and sunlight. It may also increase the risk of disease and attract pests, including corn rootworm beetles.
Kim Ricardo, SDSU Extension Forage Field Specialist, and Heather Gessner explained how livestock grazing can help reduce volunteer corn while providing other benefits to farming operations.
Benefits of Grazing Corn Stalks
Grazing corn residue provides several benefits for farms with livestock. Cattle can use the available grain, husks, leaves, and other plant material as feed. This can help maintain body condition and extend existing feed supplies for a few extra days, depending on the amount and quality of residue available.
Farmers who do not raise livestock can also benefit by renting their corn fields to livestock owners. This creates an additional source of income while helping manage spilled grain and dropped ears. Grazing may also reduce the need for herbicides used to control volunteer corn in the following crop.
Cattle naturally select the most appealing feed first. They usually eat corn grain before moving to leaves and husks, followed by cobs and stalks. This feeding behavior makes cattle useful for removing spilled grain and dropped ears that could otherwise grow into volunteer corn plants.
Planning Water and Fencing
Before allowing cattle into harvested corn fields, farmers need to plan for water and fencing. Livestock requires a reliable water supply throughout the grazing period. Temporary water systems or hauling water to the field can provide quick solutions. However, hauling water requires additional labor and time, which farmers should include when calculating costs.
If grazing corn residue becomes a regular practice, installing permanent water sources may offer better long-term value.
Fencing is another important consideration. Temporary electric fences and solar-powered fencing systems can help keep cattle within the selected grazing area. Virtual fencing technology may also help farmers manage livestock movement with less labor. These tools allow farmers to direct grazing toward areas with more available feed and improve the use of crop residue.
Managing Soil Compaction and Residue
Some farmers worry that cattle grazing may compact soil, disturb the field surface, or remove too much crop residue. However, research from the University of Nebraska provides useful information about these concerns.
A 16-year study examined how grazing corn residue affects soil properties and crop yields in a corn-soybean rotation. The study found no harmful effects on soil properties or crop yields from grazing. In fact, fall grazing increased soybean yields by 3.4 bushels per acre.
Even with these findings, farmers should manage grazing carefully. Wet or thawed soils are more likely to suffer surface damage from livestock movement. Avoiding grazing under these conditions can help limit soil disturbance. Farmers should also avoid placing too many animals in a small area.
Fields with more crop residue generally have better protection against surface disturbance than fields with little residue. Leaving enough residue behind is important because it protects the soil, supports nutrient cycling, and helps maintain long-term field health.
Calculating Stocking Rates and Grazing Days
The number of cattle a field can support depends on animal weight, corn yield, available residue, field size, and the planned grazing period. Farmers should estimate the amount of usable feed before deciding how many animals to place in a field.
A general estimate is that one pound of corn residue is produced for every pound of harvested grain. For example, a corn crop yielding 170 bushels per acre produces about 9,520 pounds of grain per acre when each bushel weighs 56 pounds.
The calculation is:
170 bushels per acre × 56 pounds per bushel = 9,520 pounds of grain per acre.
Using this figure as a rough estimate, the field produces about 9,520 pounds of residue per acre. However, cattle cannot eat all of this material. Much of the stalk remains in the field, and some residue must stay on the soil for protection.
Farmers can begin by estimating that 25% to 30% of total residue is available for grazing. Under favorable conditions, as much as 50% may be usable.
If 25% of the estimated residue is readily consumable, the calculation is:
9,520 pounds × 0.25 = 2,380 pounds of usable forage per acre.
If cattle consume 30% of that available forage, the estimated amount consumed is:
2,380 pounds × 0.30 = 714 pounds of dry matter per acre.
Next, farmers must compare available forage with the animals' daily feed needs. A 1,000-pound cow, treated as one animal unit (AU), consumes about 26 pounds of dry matter daily at 2.6% of its body weight.
The estimated grazing period is:
714 pounds per acre ÷ 26 pounds per day = about 27 cow-days per acre.
This means one 1,000-pound cow can graze the field for approximately 27 days per acre under these assumptions. Actual grazing time may be shorter because of weather, trampling, selective feeding, changing nutritional needs, and the need to leave enough residue.
For more accurate planning, farmers can divide available grazeable dry matter by the daily dry matter needs of the animals and the number of planned grazing days.
Making Grazing Work for the Farm
Grazing corn stalks can help farmers manage volunteer corn, make better use of crop residue, reduce feed costs, and create additional income. Success depends on proper stocking rates, reliable water, suitable fencing, and careful soil management. By planning grazing activities and leaving enough residue behind, farmers can support livestock needs while protecting their fields for future crops.
Photo Credit: gettyimages-awakr10
Categories: South Dakota, Crops, Corn, Soybeans, Livestock