Straight Alfalfa or Alfalfa-Grass?

By Everett D. Thomas

This field at Miner Institute was seeded with 12 pounds of alfalfa and 4 pounds of tall fescue. You can see a clear line of separation running across the field; however, the field was seeded from front to back, and the line of separation is due to two distinctly different soil types.
Photo by Everett D. Thomas.

Dairy farming may seem similar in many ways in the upper Midwest and the Northeast: family farms of various sizes, ranging from 50-cow "mom and pop" tie-stall operations with silage bags and tower silos to free-stall operations with hundreds or thousands of cows and bunker or stack silos. While farmers in both regions rely on corn silage as major forage, one big difference is how the farmers manage alfalfa.

"Lake state" dairy farmers - Michigan, Wisconsin and Minnesota - usually seed alfalfa without a grass companion crop, while a majority of farmers in the Northeast seed a blend of alfalfa and a cool-season grass such as orchardgrass, timothy or tall fescue. A Cornell University survey found that over 80 percent of alfalfa seeded in New York state included a forage grass; no data is available from other states, but it's likely that well over 50 percent of alfalfa in New England is seeded with grass, with lesser percentages in Pennsylvania and points south. The percentage of grass mixed with the alfalfa varies depending on grass species and soil type, but a 3-1 ratio of alfalfa to grass is typical.

No clear choice

It's tough to make an open-and-shut case for either straight alfalfa or alfalfa-grass, because there are advantages and disadvantages to both. Alfalfa may be the best choice on top-quality land with excellent drainage and adequate pH and fertility levels. And weed control is much easier, with a number of herbicides that will control both broadleaf and grassy weeds. After several years of wrangling in the courts, it's now legal to plant Roundup Ready alfalfa, which gives farmers an additional weed control option.

Farmers selling baled alfalfa hay prefer clear alfalfa, since some hay buyers want 100 percent alfalfa with no trace of grass. However, there are advantages to alfalfa-grass, including somewhat better resistance to winterkill, improved yield and quality under variable soil drainage and fertility conditions, and a bit of "crop insurance" in the case of a severe alfalfa winterkill, as occurred in the Midwest last winter.

Some of the reasons claimed for the superiority of straight alfalfa may be overstated. For instance, one advantage cited is the uniformity of the harvested forage. While this may be true if alfalfa is planted on excellent land, if drainage or fertility problems result in the loss of alfalfa in some areas of the field, what grows in its place - weedy grasses, dandelions, etc. - will result in variable forage quality anyway.

It's further claimed that when alfalfa-grass is harvested and stored as silage, feed quality will be variable since some areas of the field may be primarily alfalfa, while other areas are mostly grass. (Note that one of the advantages of alfalfa-grass is also mentioned as a disadvantage!)

While variable feed quality may be a problem if the forage is stored in a silage bag or small-diameter tower silo, it's much less likely to be a problem if alfalfa-grass is ensiled in a bunker silo or drive-over pile. That's because the forage is ensiled in roughly horizontal layers, most or all of the silo face is fed from each day, and on many farms the silage is further blended in a TMR mixer. Therefore, what winds up in the feed bunk on any particular day represents small amounts from many loads of harvested forage. In reality, the day-to-day changes in weather conditions, both temperature and humidity, have more impact on dry matter intake and milk production than do daily variations in forage quality in a bunker silo or drive-over pile.

The species in an alfalfa-grass seeding have the ability to adjust to varying soil conditions. The photo on page 18 shows a field at Miner Institute (Chazy, N.Y.) that in the previous year was seeded with 12 pounds of alfalfa and 4 pounds of tall fescue. You can see a clear line of separation running across the field; however, the field was seeded from front to back, and the line of separation is due to two distinctly different soil types. The soil in the front of the field is very well-drained, while the soil in the back of the field is moderately well-drained. There's almost no tall fescue growing in the very well-drained soil, while there's plenty of both alfalfa and tall fescue in the moderately well-drained soil. A seeding mixture has the potential to maximize yield and quality in fields with drainage ranging from excellent to moderate.

Ev Thomas has worked as an agronomist in New York for 45 years, first with Cornell University Cooperative Extension, then with the William H. Miner Agricultural Research Institute in Chazy, N.Y., including managing its 680-acre crop operation. He continues to work part-time for Miner Institute and is now an agronomist at Oak Point Agronomics. He has written our Forages column for 15 years and has been an expert contributor on a number of other topics.