September 5, 2017 at 3:32 p.m.

Cool-season grasses, annual forages beat 'summer slump'

Geoff Brink, a research agronomist at the USDA Forage Research Center, talked about cool-season grasses and annual forages, during a pasture walk at the Matt Martin farm, Viola, Wis.<br /><!-- 1upcrlf -->PHOTO BY RON JOHNSON
Geoff Brink, a research agronomist at the USDA Forage Research Center, talked about cool-season grasses and annual forages, during a pasture walk at the Matt Martin farm, Viola, Wis.<br /><!-- 1upcrlf -->PHOTO BY RON JOHNSON

By By Ron Johnson- | Comments: 0 | Leave a comment

VIOLA, Wis. - July in Wisconsin often brings a summer slump. That's the period from about the middle of July to mid-August, when rain is often in short supply and temperatures rise.
A recent pasture walk at the Matt Martin farm, Viola, Wis., looked at forages that can help fill feed needs during the summer slump. Geoff Brink, a research agronomist at the USDA Forage Research Center, Madison, Wis., led a discussion about cool-season grasses and annual forages.
Cool-season grasses - those that grow well in cool conditions - include orchardgrass, Kentucky bluegrass, smooth bromegrass, quackgrass, improved meadow fescue, tall fescue, reed canarygrass, festolium and ryegrass. Most cool-season grasses are perennials, lasting more than one year.
"As a group," said Brink, "they are the most productive grasses for Wisconsin graziers."
Farmers can do two things to aid the survival of cool-season grasses. They can provide the right soil fertility and they can graze them properly.
Brink said these grasses need medium or higher amounts of phosphorus in the soil. However, the most-limiting factor is nitrogen.
The best time to apply nitrogen to aid grass growth is before June, Brink said. An application can help later, but the most benefit will come if it's applied earlier. Mid-to-late August can be a good time for added nitrogen, too, if rain has been arriving.
Graziers are often antsy to get their cattle onto pasture, come spring. But Brink cautioned that grazing these grasses too early and too short can reduce the dry matter yield for the entire year. That loss can tally 300 to 400 pounds of dry matter per acre, Brink said. He suggested taking livestock off cool-season grasses when the residue is about six inches tall.
In the fall, with winter approaching, leave residue at least three to four inches high, he said. That height will still let the grasses store carbohydrates for their winter energy needs.
Grazing height does depend somewhat on the species of grass. Brink said ryegrass can safely be grazed shorter than other cool-season grasses. Even so, ryegrass will stop growing when dry conditions - like those of the summer slump - arrive.
Many graziers like to make at least some hay off their pastures. Brink said that's fine, as long as each paddock or pasture isn't mowed too often. He advised just one cutting per year - not after every round of grazing, as some farmers try to do.
On the topic of tall fescue, Brink reminded graziers to plant varieties that are endophyte free. An endophyte is a fungus that lives in the plant. Animals eating infected tall fescue can acquire a condition called vascular constriction that can make their ears and tails slough off and even cause death.
Some tall fescue varieties have been developed that are called "endophyte friendly" instead of "endophyte free." Endophyte friendly fescues, said Brink, are not well suited to Wisconsin's conditions, but do well farther south, in places like Arkansas, Kentucky and Tennessee.

Summer annuals
One way to beat the summer slump or grow emergency feed for later in the year is to plant summer annuals. Such a rescue crop can provide high-quality feed when pasture grasses slow down.
Three summer annuals that can work well are sorghum, sorghum-Sudangrass, and Sudangrass. All three need a soil temperature of 65 degrees Fahrenheit or higher when they're planted, Brink said. In southwest Wisconsin, that generally happens the last week of May or the first week of June.
All three crops also need a well-prepared seedbed, for good seed-to-soil contact. Brink said these crops might also require a little more tillage or weed suppression.
All three can also can be broadcast seeded or drilled. Brink suggested planting them in wider rows, to less the impact of trampling by cattle.
Sorghum, Sudangrass and sorghum-Sudan can also be planted in early August for supplemental feed in the fall. And, either of the three can be a good choice for renovating an old pasture or one that does not contain the preferred mix of forages.
Brink said the three respond well to grazing. But, like cool-season grasses, they store carbohydrates in the bases of their stem, so it's a good idea to not graze them below four to six inches tall.
One potential problem with sorghum, sorghum-Sudan and Sudangrass is their tendency to contain a toxin, prussic acid, at certain times of the year. Livestock can die from prussic acid poisoning if they eat sorghum, sorghum-Sudan, or Sudangrass that is very young, has been hit by frost, or has been stunted by drought.
According to Purdue University, it's usually considered safe to feed these three forages as green chop or pasture five to six days after a killing frost. And, according to Purdue University, "New shoots emerging from unkilled portions of the plant are apt to be high in prussic acid. Therefore, this forage should not be used until that new growth reaches a height of two feet."
Brink said it might be a good idea for graziers to plan on growing some types of summer annuals every year for emergency feed. After all, a normal summer brings four to six weeks of dry, hot weather.
Choose an area large enough to feed the herd during the summer slump and plant it to summer annuals two or three years in a row, Brink said. Then grow perennials on it two or three years and then start the whole cycle over.
One advantage of doing that is that a farmer is not always trying to kill a tight sod before planting. And, the best planting time can be chosen. There's no scrambling to plant because a farmer suddenly realizes he or she needs an emergency forage.
The list of summer annuals need not be limited to Sudangrass, sorghum and sorghum-Sudan. Brink said corn, oats, winter wheat and winter rye can work, too. Cool-season grasses might also be added to the mix.
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