A number of grasses show potential for use in alfalfa-grass mixes in the Upper Midwest, says Paul Peterson, University of Minnesota extension forage specialist. Seeding a grass with alfalfa can boost yield, speed drying, improve feed value and reduce winter injury and traffic damage, he points out.
Peterson says mixtures help offset field variability. High and low spots and fertility differences within fields present challenges. "Alfalfa has pretty specific soil requirements for optimum growth," he states. "In reality, it is rare to have optimum growing conditions throughout a field. Having a grass together with alfalfa will help us deal with the natural variability within fields."
Grasses can help every cutting produce well, increasing yield and profitability, Peterson says. "Many of these grasses that have a lot of yield potential also have a lot of growth in the fall, the fescues and orchardgrass for example," he reports. "So mixtures that include them need to have a fall cut. That good fall growth also provides more residue than alfalfa stubble alone to catch snow and insulate alfalfa crowns."
Some grasses will help speed hay drying, particularly smooth bromegrass, reed canarygrass and timothy. Because they produce stems with every growth cycle, they create fluffy swaths that dry faster. However, he cautions growers that leafy grasses with shiny surfaces, such as tall fescue and ryegrass, will not speed drying rate.
Grasses also have a fiber digestibility advantage. "Our standard quality system of relative feed value (RFV) continues to be a tremendous tool, but is quite alfalfa-oriented in terms of assessing true feeding potential," Peterson says. "Grasses tend to have more NDF than alfalfa, which has been viewed as a negative. However, that NDF is more digestible. The big reason we grow perennial forages for ruminant animals is for fiber. The more digestible that fiber is, the better. Growing grass with alfalfa in many situations can allow us to harvest more digestible fiber per acre than alfalfa alone." Grasses are more competitive when measured by relative forage quality (RFQ), which Peterson says is a better indicator of how a forage is going to feed.
Reed canarygrass, like smooth bromegrass and timothy, is very winterhardy. It's a sod-forming grass so it helps prevent frost heaving, and is very flood-tolerant. "Few people realize that it is also the most drought-tolerant cool-season grass," Peterson says. "It matches very well with alfalfa in terms of yield distribution. You can have more-even distribution throughout the season with reed canarygrass." One issue, though, is composition throughout the life of the stand. Alfalfa will dominate the mix early on, but reed canarygrass tends be dominant later.
Smooth bromegrass is a dependable cool-season grass with good persistence through heat and drought conditions, although it doesn't produce well during drought. Because it is a sod-former, it will help reduce alfalfa frost heaving in winter. It's very present in the first cutting, but probably not in summer and fall harvests. "If you like smooth brome, you might want to include another grass such as orchardgrass or a fescue that has better regrowth after the first cut to ensure grass presence in later cuttings," Peterson suggests.
Timothy "tends to be later maturing, which I think is one reason horse owners like it so much," Peterson says. "It is easier to get put up later without rain damage and mold." Timothy does well in cool, moist conditions and has a high spring yield but has limited presence in summer and fall cuttings.
Orchardgrass is a "good old standard." Winterhardy varieties offer good summer and fall forage production. "Keep the seeding rate low, and cut low," he advises. "The more stubble that is left, the more rapidly orchardgrass regrows. Cutting it low is a good way to keep it in check when it is grown with alfalfa."
Tall and meadow fescues offer high yield and quality, and a yield distribution that matches alfalfa. However, fescues can be too competitive if seeded heavily or in the same row with alfalfa, and can be difficult to wilt to hay moisture levels. Meadow fescue is very winterhardy, whereas tall fescue's hardiness is similar to that of orchardgrass.
Contact Peterson at peter072@umn.edu.