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Extension > Agriculture > Dairy Extension > Forages > Alfalfa mixtures with orchardgrass or tall fescue outperform alfalfa alone

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Alfalfa mixtures with orchardgrass or tall fescue outperform alfalfa alone

Paul Peterson, Extension Forage Agronomist
August 13, 2011

In their second production year (2010) at Underwood, MN, mixtures of alfalfa with either orchardgrass or tall fescue had approximately 15% more milk production potential per acre (avg. 17,370 lb milk/ac) than alfalfa alone (14,910 lb milk/ac). Their total-season dry matter (DM) yields, however, were similar, averaging 6.3 ton DM/ac. Season-average grass percentages were 54% orchardgrass and 25% tall fescue.

In their second production year (2010) at Hutchinson, MN, alfalfa mixed with orchardgrass had approximately 28% more milk production potential per acre (15,580 lb milk/ac) than alfalfa/tall fescue or alfalfa alone (avg. 12,190 lb milk/ac). However, alfalfa mixed with either orchardgrass or tall fescue yielded approximately 15% more DM/ac (avg. 5.3 ton DM/ac) than alfalfa alone (4.6 ton DM/ac). Season-average grass percentages at Hutchinson were 42% orchardgrass and 15% tall fescue in 2010.

These forages are within replicated, small-plot trials seeded August 2008 on farms in Otter Tail (Underwood) and McLeod (Hutchinson) counties. Two varieties each of orchardgrass (Baridana and Potomac) and tall fescue (Fawn and Select) were seeded at 6 and 8 lb/ac, respectively, in mixtures with alfalfa seeded at 10 lb/ac. Alfalfa alone was seeded at 15 lb/ac. Other grasses in the trial are shown in Table 1.

Table 1.  Total-season dry-matter yields, season-average grass percentage, and total-season milk production potential (Milk 2006, UW) of alfalfa/grass mixtures at Underwood and Hutchinson, MN, in 2010.
Mixture Underwood Hutchinson
T DM/ac % Grass Lb Milk/ac T DM/ac % Grass Lb Milk/ac
Alfalfa/Orchardgrass 6.20 54 17,220 5.45 42 15,580
Alfalfa/Tall Fescue 6.43 25 17,520 5.09 15 12,320
Alfalfa Alone 6.19 0 14,910 4.60 0 12,070
Alfalfa/Meadow Fescue 6.14 33 16,140 4.72 12 12,040
Alfalfa/Meadow Bromegrass 6.04 37 14,690 4.76 8 12,170
Alfalfa/Reed Canarygrass 5.99 18 15,280 4.62 6 12,170
Alfalfa/Perennial Ryegrass 5.93 11 14,440 4.66 11 11,710
Alfalfa/Smooth Bromegrass 5.65 34 14,270 4.64 6 11,740
Alfalfa/Festulolium 5.51 22 15,020 4.77 14 12,030
Alfalfa/Timothy 5.21 48 13,290 4.34 7 11,280
LSD (0.05) 0.56 5 1,160 0.38 6 1,490
Overall Average 5.93 28 15,170 4.76 12 12,310

The trials were fertilized with approximately 50 lb sulfur/ac and 3 lb boron/ac each year, potassium according to soil test results, and 100 lb N/ac/yr applied in split applications of 50 lb/ac in spring and 50 lb/ac immediately after the third of four annual harvests. Plots were cut to a 4" residual, as is recommended for alfalfa/grass mixtures. Harvest dates in 2010 at Underwood were May 20, June 22, July 28, and September 18; Hutchinson harvests were May 28, June 29, July 29, and September 22.

At Underwood in 2010, mixtures of alfalfa with either meadow fescue (33% grass), meadow bromegrass (37% grass), reed canarygrass (18% grass), or perennial ryegrass (11% grass) were also among the highest DM-yielding treatments. Mixtures of alfalfa with smooth bromegrass (34% grass), festulolium (22% grass), or timothy (48% grass) had the least DM yield, averaging 5.5 ton DM/ac. Mixtures of alfalfa with either timothy, smooth bromegrass, or perennial ryegrass had the least milk production potential per acre in 2010, averaging 14,000 lb milk/ac.

At Hutchinson in 2010, alfalfa alone as well as the mixtures of alfalfa with either timothy (7% grass), reed canarygrass (6% grass), smooth bromegrass (6% grass), or perennial ryegrass (11% grass) were among the least in DM yield. The alfalfa/orchardgrass mixture stood alone in superior milk production potential per acre. All other treatments had statistically similarly less milk production potential.

Grass percentages in 2010 were greater at Underwood than Hutchinson, averaging 28 vs. 12%, respectively. This occurred despite identical seeding rates and methods, and seeding dates only 4 days apart in August 2008. I believe temperature differences in late summer into early fall 2008 caused this difference, with warmer establishment temperatures at Hutchinson favoring alfalfa dominance, and cooler establishment temperatures at Underwood favoring more substantial grass establishment.

These trials are being harvested in 2011 with targets of five harvests at Hutchinson and four harvests at Underwood. An additional trial in its second production year near Avon (Stearns Co.), MN, is being harvested three times in 2011.

Our data are demonstrating the potential of alfalfa/grass mixtures to outperform alfalfa alone. However, we are seeing considerable variation across on-farm locations. Producers are encouraged to experiment with different grass species and varieties on their own farms, comparing grasses alone and/or in mixtures with alfalfa and/or with alfalfa alone. While our trials included only 2-species mixtures to maintain reasonably sized experiments, 3- or 4-species mixtures may be better on more variable land.

Acknowledgements: Key UMN-Extension Educators involved in this project include Doug Holen, Jim Paulson, Dan Martens, Jim Salfer, Craig Roerick, Nathan Winter, Betsy Wieland, Phil Glogoza, and Dave Nicolai.

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