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Grazing corn residue – impacting cow performance and yield

Travis Meteer for Progressive Forage Published on 31 August 2017
Cows graze cornstalks

A three-year research project, conducted by University of Illinois, looks at whether grazing corn residue impacts subsequent crops.

Cows graze cornstalks at the Dudley Smith research farm outside of Pana, Illinois.

Corn residue is the most abundant, affordable feedstuff in the Midwest. Yet each year, acres upon acres of residue go unutilized, even on diversified farms. While it’s well-documented that grazing cornstalks is a huge cost saver for the cow-calf enterprise, some landowners still question the impact of grazing on the following row crop.

Researchers at the University of Illinois sought to help answer questions about subsequent crop yields with a three-year trial conducted at the Dudley Smith research farm located outside of Pana, Illinois. For those of you not familiar with Illinois geography, this location is in the heart of row crop country; the soil is black and deep, and the land is as flat as your kitchen table.

Methods

Over three years, the researchers measured cow performance, residue quality and utilization, as well as subsequent crop yield. Two grazing methods: strip grazing (SG) and continuous grazing (CG), and an ungrazed control (CT) were applied to the acreage. Following corn harvest, cows were allowed to graze for six weeks. The CG treatments were allowed access to the full paddock throughout the entire six weeks.

In SG treatments, the paddock was divided into three strips. Cows were allowed access to a new strip every 14 days. No back fencing was used. Thus, after 14 days, cows had access to the first strip and the new (or second) strip. And during the last 14 days, the cows had access to the entire paddock. CG cows were stocked at 1.2 cows per acre.

SG cows were stocked at 3.6 cows per acre for the first 14 days, at 2.4 cows per acre for the second 14 days, and 1.2 cows per acre for the last period.

Residue grazing started in late September in the first year, in early November the second year and in early October the third year. Cows were supplemented a 50-50 blend of corn gluten feed and soybean hulls to help achieve cow nutrient requirements. The acreage was maintained in continuous corn during the trial period. Spring tillage occurred each year with a vertical tillage tool.

Results

The researchers highlighted four main takeaways. First, continuous grazing and strip grazing corn residue did not affect subsequent crop yield. This is in agreement with research in more arid climates.

Unlike some research, this trial allowed cows to graze residue for six weeks following harvest and then the cattle were removed from the acreage. Thus, grazing residue for a six-week period following corn harvest did not impact subsequent crop yield.

Next, cows grazing helped remove and incorporate residue, but not too much. Figures shown in Table 1 illustrate the residue available pre-grazing and the residue available post-grazing. Roughly 4 tons of dry matter was available for grazing.

Corn residue availability

Residue available after grazing in either treatment was close to half of what was available, thus leaving an adequate amount of residue to hold and shield the soil. It is worth mentioning that in the ungrazed control paddock, only 78 percent of the residue remained. Loss to wind and degradation of plant matter likely explain the loss.

The shift in percentages of components of the residue is similar to findings in other university trials. Cattle consumed mainly husk and leaf. The percentage of cob also declined. This could be due to some intake by the animal, but more likely is due to trampling and incorporation into the soil.

The amount of stalk increased in percentage due to reduction of other components. The actual weight of the stalk component was similar across all treatments, post-grazing. This further illustrates the selectivity that cattle graze in cornstalks.

Also, cows that strip grazed corn residue had increased bodyweight gains and weighed more than cows continuously grazed. This is likely explained by a few factors. First, because cows selectively graze corn residue, the strip graze treatment potentially partitioned nutrients more evenly over the grazing period.

Measures of residue showed SG had more nutritive quality towards the end of the grazing period. Also, the SG cows were allowed less area to travel for the first two 14-day periods, and it is logical the CG cows spent more time searching for palatable residue.

This increased time spent traveling the area not only resulted in increased maintenance requirement, but also could have increased trampling of husks and leaves, thus reducing available residue for consumption.

Finally, although treatment yields were similar, there was a reduction in crop yield in the first strip compared to the second strip. The researchers speculated this was a result of increased traffic to and from feed and water provided in the first strip.

In this study, supplement and mineral feeders, along with water troughs, were permanently located in the first strip. Yield mapping showed a visual illustration that higher traffic areas around the water source, mineral feeders and feedbunks did result in some yield drag. This may warrant moving water and feeding areas to limit cattle trailing in the same areas.

Summary

Farmers that operate on heavy, deep, poorly drained soils can still benefit from cornstalk grazing. Some attention and management to reducing traffic and avoiding higher stocking rates during wet periods may be justified.

Most Midwestern farmers are not limited in the acreage of cornstalks, so stocking density is easily remedied by allowing more acres per paddock or by simply using a continuous grazing system.

Cattle can help reduce residue buildup by not only consuming a portion of the residue, but also incorporating some components into the soil. In a continuous corn crop rotation, this may be a strong benefit.

Grazing residue is an important component to controlling cost in Midwestern beef cow-calf herds. While limitations such as water access, fence and labor for fencing will continue to be challenges, a small investment to facilitate residue grazing is a sound investment.

Knowing that grazing will help reduce feed costs for the beef enterprise without sacrificing row crop yields makes it a no-brainer for farmers.  end mark

PHOTO: Cows graze cornstalks at the Dudley Smith research farm outside of Pana, Illinois. Photo by Blake Lehman, University of Illinois graduate student.

Travis Meteer
  • Travis Meteer

  • Extension Educator – Beef
  • University of Illinois
  • Email Travis Meteer

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