Consider Relative Reproductive Maturity of Grasses Seeded With Alfalfa
Our breeders continue to advance genetics of many cool-season grass species. When considering a particular cool-season grass species or variety, factor in the time of harvest of the alfalfa as well as the grass variety’s Reproductive Maturity (RM). This is most important for the first cutting each year of alfalfa-grass mixtures, as the crop grows longest during this period. Ideally, select a grass species variety in which the RM is similar to alfalfa, so that maximum yield and quality are achieved. Furthermore, the goal is at time of harvest the yield and quality of alfalfa is maximized (approximately at the bud stage, depending on animal needs), while the grass species yield and quality is also maximized.
Figure 1. The relationship between alfalfa maturity stage and total forage, stem, and leaf yield and forage digestibility. Source: C. Sheaffer. In Undersander et al., 2014. Alfalfa Management Guide
O-Indicates ideal harvest timing of forage grass to maximize yield and quality.
Figure 2. The general relationship between forage yield a forage quality as affected by stage of maturity of grasses. Source: https://extensionpubs.unl.edu/publication/g2185/2013/html/view
O-Indicates ideal harvest timing of forage grass to maximize yield and quality.
Figure 3. The Forage Maturity Matrix compares the relative reproductive maturity of cool‑season grasses and legumes—including alfalfa—so producers can easily cross‑reference species on a single scale.
DLF’s Forage Maturity Index (Fig. 3) has been designed to accommodate the broader range of species and maturities utilized in the North American forage industry. It has a 9-point index with a maturity difference of approximately three days per unit, reflecting Oregon conditions. Variance with this index may occur in different regions since some cultivars are more temperature dependent, while others may be more day length dependent in maturity. With all species using the same Maturity Index Rating System, the maturity range of various forage species can now be directly compared on the same chronological maturity index (the black index scale at the top of the matrix). The gradient blocks in the Forage Maturity Matrix Species reflect the maturity range of available varieties within the species. The respective maturity of public varieties using the traditional nomenclature of each early, medium, and late is superimposed on the index. A maturity index in one species corresponds to the same maturity in another forage species.
This tool allows producers to select grass varieties that best align with alfalfa harvest. It is also important to note that post first crop harvest, the frequency of harvest typically eliminates chances of grass varieties to approach heading in consecutive cuts.
Primary Cool-Season Grass Species Seeded with Alfalfa
Orchardgrass
When selecting an orchardgrass variety, it is important to select a late-maturing orchardgrass. Older genetics of orchardgrass tend to mature too early when seeded with alfalfa and have the potential to reduce overall quality of the alfalfa-grass mixture if it enters reproductive stages prior to harvest. New varieties classified as “late” will align with alfalfa in regard to harvest and maximize yield and quality potential at alfalfa harvest. Selecting a late maturing orchardgrass to be a companion with alfalfa is recommended.
Tall Fescue
When considering a tall fescue as a companion, select a late-maturing tall fescue. Older genetics of tall fescue, like orchardgrass, tend to be on the earlier side of RM when compared to alfalfa. Select a late maturing tall fescue to be a companion with alfalfa.
Meadow Fescue
When selecting a Meadow fescue, select a mid-late maturing variety. Meadow fescue maturity at alfalfa harvest tends to align fairly well; however, it is still important to evaluate variety comparisons.
Timothy
This species is very late-maturing compared to alfalfa’s optimum harvest timing. New varieties classified as “early” will align best so that the yield and quality of the timothy at the time of alfalfa harvest is maximized.
Festulolium
Some challenges may exist when selecting a festulolium variety, as it is a cross between ryegrass and tall fescue or ryegrass and meadow fescue. Typically festulolium’s RM will be closely linked to the more dominant parent of the cross, so it is important to know the cross of the festulolium.
Perennial Ryegrass
When selecting a perennial ryegrass, some challenges exist as relative reproductive maturities tend to be broad. Ideally selecting a variety that is close to beginning bloom of alfalfa will maximize yield and quality of the perennial ryegrass at the time of alfalfa harvest.