Some Wisconsin farmers harvest red clover three times during the summer, as if it were alfalfa; others take two cuts that are often made too late for optimal forage quality. University of Wisconsin-Madison researchers say neither of those approaches is best.

“For optimum forage yield, quality and persistence, we found that current red clover varieties should be harvested three times during the year when plants are between bud stage and 20 percent bloom,” says Daniel Wiersma, an agronomist at the Marshfield Agricultural Research Station. “Of those harvests, we found that it”s best to make two cuts before Sept. 1. If the clover has regrown enough to warrant a third cut, farmers should make that cut after Oct. 15 or a frost.”

“Making three cuts during the summer can put too much stress on red clover plants,” according to Richard Smith, a forage scientist with the UW-Madison Department of Agronomy and USDA Agricultural Research Service. That”s especially true if the weather is dry during late summer or fall. “Clover doesn”t have a deep tap root like alfalfa,” he says. “If it”s cut too often under dry conditions, you won”t get enough regrowth to have healthy plants going into the winter.”

Wiersma and Smith are part of a team from the College of Agricultural and Life Sciences and USDA”s Dairy Forage Research Center that is studying how harvest management systems affected red clover forage yield, quality and persistence.

Although alfalfa is the leading forage legume in Wisconsin by a wide margin, farmers often turn to red clover if their soils are poorly drained, low in fertility or acidic. Typically, farmers take one cut the year they seed red clover and then harvest it for two more years.

Wisconsin farmers now grow 500,000 acres to 800,000 acres of red clover — most with grass – for hay, silage and pastures, according to Smith. “Most of those acres are in the northern two-thirds of Wisconsin,” he says. “But red clover pastures are common in southwestern Wisconsin.”

“In this study we analyzed harvest systems for red clover as a monoculture,” Smith notes. “We”re completing a similar study of red clover planted with grass.”

Management recommendations for cutting forages typically emphasize early and frequent harvests to maximize forage yield and nutrient quality. However, early and frequent cuttings can reduce the persistence of red clover – a short-lived perennial crop — especially if the soil is dry.

The forage scientists evaluated Arlington, Atlas, Marathon, Reddy and Red Star red clover under five harvest management systems at the Arlington, Marshfield, Spooner and Ashland Agricultural Research Stations. The harvest systems included:

1. two summer cuts at bud stage;

2. three summer cuts at bud stage;

3. two summer cuts at 20 percent bloom plus a late fall cut;

4. two summer cuts at 40 percent bloom plus a late fall cut; and

5. two summer cuts at 40 percent bloom.

The researchers also measured red clover stands and first-cut forage yields in the fourth year to determine persistence. In addition, they analyzed the nutritional quality of Marathon, which they consider representative of the five varieties. All five are disease-resistant and more persistent than varieties developed before 1970.

“There were only small and inconsistent differences in yield among the five cultivars. Of the five harvest management systems we evaluated, we consistently found that the third system – two summer cuts at 20 percent bloom and a late fall cut – yielded the most forage during both harvest years at all locations,” Wiersma says.

“In the north – Ashland and Spooner – the yields from the systems where we cut at 40 percent bloom were not significantly different from the harvest at 20 percent bloom. But harvesting red clover later than 20 percent bloom results in lower quality forage.

“Red clover cut at the bud stage had the highest concentration of crude protein and lowest concentration of neutral detergent fiber and acid detergent fiber,” he says. “In northern Wisconsin, however, cutting at the bud stage reduces total seasonal yield compared with cutting at 20 percent bloom.

“Red clover stands exceeded 60 percent in the second year after planting and produced more than 3 tons of dry matter per acre at all the locations,” Wiersma says. “The different harvest management systems didn”t affect red clover persistence in this study.

“A fall harvest didn”t significantly reduce yield in the following year,” he says. “If there”s been sufficient regrowth, farmers can make a final cut after a killing frost or after Oct. 15 without harming the stand.”

Others participating in the study were Debra Sharpee, formerly of the USDA Dairy Forage Research Center and now with Pioneer Hybrid, Mike Mylnarek of the Ashland Agricultural Research Station, Robert Rand of the Spooner Agricultural Research Station, and Dan Undersander, an extension forage specialist in the Department of Agronomy.

The study was supported by state funding to the UW-Madison College of Agricultural and Life Sciences and federal funding to the USDA Dairy Forage Research Center.