Evaluate and manage hay field injuries

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It was a rough winter for many hay fields in northern Ohio. Considering the stressful conditions last year, followed by a cold and wet winter, it is not surprising that many forage stands took a beating this winter.

Alfalfa fields seem to be the hardest hit. The 2007 Easter freeze followed by very dry conditions in 2007, left alfalfa stands in a weakened state going into the winter.

In northeast Ohio, the most common injury in alfalfa has been due to frost heaving.

Heaving

Where a late fall harvest was made, no plant cover was left to insulate against alternative freeze-thaw cycles. The result was severe heaving, especially where drainage was not excellent.

Research has demonstrated that early November harvests can dramatically increase heaving in alfalfa stands compared with where a late harvest is not made. This was observed this year, but in some cases, heaving occurred even where adequate fall growth was left on the field going into the winter.

In northwest Ohio, there are many alfalfa hay fields that suffered severe winter injury without heaving. The warm temperatures and very wet soil conditions late last fall reduced the ability of alfalfa to harden off properly.

As a result, the plants developed less tolerance to cold temperatures.

The big snow melts and heavy rains during in the winter in northwest Ohio also contributed to lack of oxygen in the root zone, which put the plants under additional stress during the winter.

Slow recovery

Grasses across the state showed slow spring recovery this year. This was likely due to overgrazing last year as well as the stressful winter conditions.

A careful inspection of all forage stands at this point in time is very important. A “windshield inspection” is inadequate to accurately assess the health of stands.

Walk your fields and get a broad view to determine whether spring growth appears uniform. Then take a closer look at the condition of individual plants. In alfalfa, plants with crowns heaved up 2 or more inches are already dead, or are in the process of desiccating and will soon die.

Plants that are heaved 1 inch or less will continue to grow and produce yield this year, but not to their full potential. Slightly heaved plants are more prone to desiccation and injury by wheel traffic, or to being cut off below the crown by harvesters.

Stands entering the winter with elevated crowns are likely to suffer above-average winterkill.

In fields with moderate heaving, plan on harvesting at a later stage than normal (bloom stage) and raise the cutter bar at harvest sufficiently to clear the crowns.

Stand survival

If plants settle back into the soil during the year, stands should survive until next year. Stands entering the winter with elevated crowns are likely to suffer above-average winterkill.

To evaluate forage stands, estimate the number of live plants per square foot. Second-year stands (seeded last year) should have 10 to 12 plants per square foot, and third year or older stands should have five to six plants per square foot for optimal yield potential.

When making plant counts, consider only those plants that appear healthy with vigorous shoot growth. Visually estimate the ground cover of desirable forage plants as the stand develops 4 inches to 6 inches of growth.

Stands with more than 80 percent ground cover and good vigor will produce excellent yields; stands with 60-80 percent ground cover should produce fair yields; stands with 40-60 percent ground cover will probably produce yields in the 60 percent range of normal; and stands of 20-40 percent ground cover will yield less than half their normal potential.

Weeds

Weeds will become a real problem in the thinner stands, and overseeding with grass or destroying the stand and rotating out to another crop should be considered.

One option to boost hay yield this year in winter-injured alfalfa stands is to interseed a small grain as soon as possible. Interseeding oat or triticale are both very good options, which will boost first-cutting yield.

Then, if the stand is to be kept for a couple years, interseed orchardgrass or another perennial grass of choice into the alfalfa right after an August cutting. Italian ryegrass is another good option for interseeding into damaged alfalfa north of Interstate 70 in Ohio.

If the stand is to be kept beyond this year, include orchardgrass or perennial ryegrass with the annual ryegrass. Sudangrass or sorghum-sudangrass can be interseeded into alfalfa in mid-May for increasing yield all summer.

Sudangrass will be a little easier to make dry hay with, but it is still difficult to dry. The stand should be cut while the sudangrass is in the vegetative stage before it gets too stemmy.

Other options

Making balage or grazing is usually a better option with the warm-season annual grasses. If the alfalfa stand is very poor and forage is really needed this year, rotating out to corn silage may be the best option, especially where silage harvesting is possible. Corn silage will produce high tonnage of energy dense feed.

In addition, nitrogen fertilization of corn after alfalfa can be drastically reduced. Corn after alfalfa rarely responds to more than 30 pounds of nitrogen applied as starter fertilizer.

Finally, keep in mind that a forage stand that is marginal and would not provide economical hay yields may still be profitable if it is harvested by grazing animals.

Interseeding an annual and perennial grasses and grazing the stand often can extend the stand’s useful life by a year or more.

About the Author

The author is an associate professor in the Department of Horticulture and Crop Science at Ohio State University. More Stories by Mark Sulc

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