Yes. Since Italian ryegrass has been popular throughout Europe and the southern United States for many years, numerous varieties are available. As shown in the study by Albrecht, there are early or late maturity varieties and diploid or tetraploid varieties; however some may be annual ryegrass rather than Italian. Tetraploid ryegrasses usually produce fewer but larger tillers with wider leaves than diploids (Sulc and Albrecht, 1996). A trait of Italian ryegrass that may or may not become apparent after establishment is heading. During the summer of 2007, numerous varieties promoted as Italian ryegrass were evaluated in Wisconsin and Michigan to assess heading (Table 2) (Undersander et. al 2007). Once Italian ryegrass heads, quality declines; therefore, non-heading varieties may be preferred.

At what rate should Italian ryegrass be planted with alfalfa?

Seeding rate is very important for Italian ryegrass / alfalfa mixtures. While all producers would like to harvest a large amount of high quality forage even in the seeding year, an excessive rate can hurt the yield of the established alfalfa in following years.

Chart 1 summarizes a study in Clark County, WI. Five, ten, and twenty lbs/acre of Italian ryegrass were no-till planted with Italian ryegrass in 2005. There were no yield differences between seedings with five, ten, and twenty lbs/acre of Italian ryegrass during the establishment year; meanwhile, the alfalfa alone treatment had a yield that was 17% less than the maximum. At the end of the growing season, the number of stems of alfalfa per square foot was counted. Sixty-three, 42, 36, and 30 stems per square foot were counted in the pure alfalfa, five, ten, and twenty pounds per acre of Italian ryegrass, respectively.

In the first year of established alfalfa, the yield decreased as the Italian ryegrass planting rate in the previous year increased. The recommended seeding rate for Italian ryegrass with alfalfa is two to four pounds per acre.

How does weather influence Italian ryegrass?

Italian ryegrass grows most vigorously in cool, wet environments. As observed in the heading study, the tendency to express heading changed by location and variety. This indicates there is an interaction between environment and variety. Sulc and Albrecht (1992) state, “Ryegrass will be less desirable than oats or barley as a cover crop at each moisture extreme. The ryegrass can be too competitive and reduce alfalfa stands in very cool and wet growing conditions, especially on poorly drained soils. They may not provide as good ground cover as oats in dry conditions.” Use of Italian ryegrass is not recommended on droughty (sandy) soils.

Italian ryegrass has an advantage over oats as high quality dairy cattle forage when used as a companion crop. Initial research with Italian ryegrass used NDF and ADF digestibility measurements. Under those measurement techniques, while better than other grasses, Italian ryegrass did not appear as desirable as alfalfa. However, after the introduction of NDF digestibility (NDFd) and Relative Forage Quality (RFQ), high NDFd of Italian ryegrass coupled with good crude protein levels shows Italian ryegrass can make suitable dairy forage when harvested in a timely manner.

Chart 2 shows results from a study planted at Lancaster, WI in 2005. Alfalfa with 37% Italian ryegrass had considerably greater NDFd than pure alfalfa. To achieve both high quality and yield, Italian ryegrass / alfalfa stands are first harvested approximately 60 days after planting. Additionally, while oats is low in palatability, making it difficult to include in dairy rations, Italian ryegrass is much more palatable and can make excellent dairy cow feed.

References

Sulc, R.M. and K.A. Albrecht. 1992. Ryegrass Companion Crops for Alfalfa Establishment. Agronomy Advice. University of Wisconsin-Madison.