Late maturing varieties of annual (Italian) ryegrass hold some potential for pastures in a management intensive rotational grazing (MIRG) system. However, in a 1997-98 on-farm study in southern Wisconsin, annual ryegrass did not make a contribution to pasture yield. In addition, frost seeding annual ryegrass over an existing pasture met with limited success. But researchers found that overall forage quality in a pasture was improved by adding annual ryegrass. The researchers note that these results must be interpreted with caution due to the limited number of farms involved.

Several Wisconsin graziers conducted ryegrass research in collaboration with the UW-Madison Center for Integrated Agricultural Systems (CIAS), Carl Fredericks of GrassWorks, Inc., Dan Undersander of the UW-Madison Agronomy Department, and Laura Paine, now Columbia County Extension Crops and Soils faculty. Iowa County dairy grazier Paul Bickford and Olds Seeds Company provided the seed for the study.

Seeding and sampling

In both years of the study, ryegrass establishment was a problem. “Establishment is most successful when conditions are cool and moist, and when soil contact with the seed is increased,” Fredericks notes. Cultimulching appears to improve establishment, but adequate soil moisture and limited competition also play a role.

Graziers frost seeded the ryegrass in existing paddocks. With one exception, the sites were upland, well-drained loamy soils. The other site was on a low lying floodplain. All of the ryegrass varieties were seeded at a rate of 20 to 30 pounds per acre, with each farmer using his own equipment to broadcast the seed in strips. An unseeded check strip separated the varieties of ryegrass, except on one farm in 1997.

In late April and early May of 1997, five graziers broadcast ryegrass seed on their farms. Two used a three-point PTO-powered seeder on their tractors. One pulled a chain link harrow behind the tractor; the other pulled an offset disk and cultipacker. One grazier broadcast ryegrass seed with a hand-crank seeder, and two used Herd seeders on all-terrain vehicles (ATVs). One farmer used an ATV with a cultimulcher to prepare the strips and rolled the strips with the cultimulcher wheels after broadcasting.

The cool, dry spring of 1997 was not ideal for frost seeding. However, these conditions did mean less competition from established grasses. Establishment of ryegrass was most successful where cultivation had occurred, and on the farm with the low lying field. The two sites with no cultivation showed little ryegrass growth by July and were not sampled further.

Three farms were sampled six to seven times in 1997 from June through October. Just before the strips were grazed, researchers sampled six randomly chosen locations in each strip using a half-meter square frame. They recorded estimates of the percentage of ground covered in grass, legume, weeds, and bare soil and clipped the forage within the frame. They analyzed grass clippings to determine how much forage was available for grazing at each sampling (forage availability) and forage quality.

During 1998, three graziers participated in this ryegrass study. In early to mid-April, two prepared their fields by grazing before seeding. One grazier broadcast seed using an air seeder, one used a Herd seeder on an ATV, and one used a PTO-powered seeder on a tractor pulling a chain link harrow. Despite favorable early season growing conditions in 1998, ryegrass did not establish well. The favorable growing conditions resulted in strong competition from existing pasture plants. The 1998 results have limits since they are from only one farm and are unreplicated.

Forage availability

Average forage availability per sampling for 1997 ranged from 1,430 pounds per acre for the variety Tetragold to 1,072 pounds per acre for the variety Aubisque, a perennial included for comparison. The unseeded check plots yielded about the same as the average ryegrass seeded plots. “Any suppression of growth caused by cultivation of the ryegrass plots appeared to have been compensated for by the growth of the ryegrass varieties, except for the varieties Aubisque and Sikem,” notes Undersander.

Nitrogen fertilization had a strong effect on forage quantity. Average forage availability in 1997 was higher at the two farms where nitrogen fertilizer was applied than at the farm where no nitrogen was applied (1,375 versus 1,000 pounds per acre per sampling).

The lowest forage availability on all three farms occurred in June (average of 890 pounds per acre) and was highest in September (average of 1,478 pounds per acre). All paddocks showed a pattern of higher forage availability in July and September, and lower levels in June, August, and October. Fredericks says, “This pattern may reflect a compressed version of the typical cool-season grass growth curve in response to the cool dry weather in late spring.” The August decline in growth is typical, as is a September flush of growth as temperatures decline and rainfall increases. Stands of annual ryegrass that survived the mild winter of 1997-98 produced a lot of forage early, but headed out quickly, Fredericks adds.

The researchers did not compare forage availability between varieties in 1998 because of the low proportion of ryegrass in the plots. Average forage availability across varieties for the season was 927 pounds per acre. Fertilized plots averaged 1,012 pounds per acre in available forage compared to 842 pounds per acre for unfertilized plots. Of the two varieties that did establish well on one farm in 1998, Sikem responded to nitrogen fertilization with about a 50 percent difference in average forage availability. Multimo forage availability was similar in both fertilized and unfertilized plots.

Forage quality

In 1997, crude protein levels of the ryegrass varieties ranged from 20 to 22 percent, with only one variety lower than the unseeded check plot. Fiber levels, both acid detergent fiber (ADF), and neutral detergent fiber (NDF), were lower in the seeded plots compared to the check plots. Relative feed values (RFV), which are inversely related to ADF and NDF levels, were higher in the all seeded paddocks than in the unseeded check plot.

Forage quality was better for the second through fifth grazing cycles (July through September), and was relatively poor for the first and last cycles (June and October). Average crude protein levels for ryegrass plots ranged from 23.5 percent in August to 18.9 percent in October compared to 22.2 percent in August and 17.6 percent in October for the check plots.

Ryegrass suitability

The best strategy for incorporating ryegrass in a MIRG system is to choose a variety that increases forage quality without sacrificing forage availability. Results from the 1997 study show that all tested ryegrass varieties improved forage quality over the check plots in terms of relative feed value, and nearly all increased crude protein levels. Five of the eight varieties showed yields similar to the check plots, suggesting that the combination of cultivation (setting back existing sod) and growth of the seeded varieties only displaces perennial grass plants rather than thickening the stand.

The perennial variety Aubisque grew 230 pounds of forage less per acre than the check plot, showing suppression of forage availability. Tetragold was the only variety tested with a much higher forage availability than the check plot (130 pounds per acre more), but it was of a low quality.

Among tested varieties, forage availability was inversely related to forage quality. Sikem, with the highest RFV, had the second lowest yield. The perennial Aubisque had the second highest RFV but the lowest yield. But the highest yielding variety, Tetragold, had an average RFV of just over 120-higher only than the check plots and the early maturing variety (Marshall).

Overall, Multimo, Urbana, and Tetrabana (a blend of three varieties) performed well, yielding as well as the check plots with much higher RFVs. Tetrone, the third variety included in the Tetrabana blend, had lower forage availability than the others but had one of the highest RFVs, equivalent to the perennial variety.

Graziers need to not only carefully consider ryegrass varieties but also put extra effort into its establishment. “We’ve only scratched the surface of annual ryegrass establishment methods in this study,” says Fredericks. Research is underway to determine which varieties establish best.

Despite its limitations in terms of establishment and yield, annual ryegrass can make a contribution to pasture quality. Undersander notes, “Annual ryegrass seed tends to be inexpensive enough that graziers can give it a try to boost pasture quality, but they shouldn’t expect it to increase pasture yield.”

Contact CIAS for more information about this research.

Published as Research Brief #47
January, 2000