Cherney noted the claims of alfalfa marketing companies, which make assertions like: fine stemmed, superior forage quality, excellent feed value, higher feed intake, maximizing forage quality, superior digestibility, improved milk production, high multifoliate leaf expression, lower lignin, higher NDFD (neutral detergent fiber digestibility) and RFQ (relative feed quality). Through research, Cherney would like to help verify those claims.
Cherney and Craig Sheaffer, University of Minnesota, received one of nine research grants from the National Alfalfa & Forage Alliance through the U.S. Alfalfa Farmer Research Initiative (checkoff funds) to evaluate progress in alfalfa forage quality improvement. To that end, he and colleagues have 24 alfalfa cultivars/germplasms planted in Minnesota and New York.
The test plots are 6 feet by 20 feet with replicates. One sample set was placed in 2017, and two sample sets are scheduled for planting in 2018. Each sample set consists of five sampling dates over two weeks. The goal is to compare differences in forage quality and gauge how quality changes over time.
New York has several conditions that do not lend well, however, to straight alfalfa stands, including sub-optimal soil drainage. In addition, winter weather is variable and snow cover is inconsistent; about every other year it’s common for alfalfa to break dormancy and grow 2 to 4 inches in January.
New York, while one of the top forage production states, doesn’t rank higher than 15th in the nation for alfalfa production, and over 85 percent of alfalfa in New York is sown with grass. Throughout the rest of the country, less than 10 percent is sown with grass on average. Cherney listed advantages to alfalfa-grass mixes: higher yields, longer stand life, less winterkill, less traffic damage, fewer pests and diseases, wider harvest window, improved soil conditioning and less erosion.
Cherney noted that nutritionists are relatively comfortable with formulating rations with alfalfa-grass mixes in the Northeast, and dairy feeding trials support the claim that an alfalfa-grass mix will maintain milk production. However, several factors affect alfalfa percentage and grass percentage in the mix, which is perhaps the biggest challenge to an alfalfa-grass mix. Those conditions include drainage, pH, grass species, grass seeding rate, soil compaction and spring seeding date. After the stand is planted, there are still fertility and other issues that will affect the percentage of alfalfa-to-grass in the stand, including manure application, nitrogen fertilizer, potassium fertilizer, stand age, cuts per season, stubble height in-season and stubble height in fall.
Cherney said one of the foremost claims of alfalfa companies recently has been maintaining quality with delayed cutting through the introduction of lower lignin varieties. However, Cherney says grass drops in NDFD 1 percentage unit per day and alfalfa drops 0.5 percentage unit per day, which means grass quality decreases a lot faster than alfalfa, and in a mixed stand that can affect digestibility significantly, which can change milk production (see Figure 1). In summary, the more grass that shows up in a stand, the fewer days producers have to play with in terms of delaying harvest, compared with pure alfalfa stands.
The major downside to an alfalfa-grass mix versus a straight alfalfa stand is the fluctuating percentage of grass in the stand. Getting and keeping 20 to 30 percent grass, Cherney says, is by far the biggest challenge.
Given the challenges of a mixed stand, Cherney said Cornell’s research has thus far made the following recommendations:
- Meadow fescue is the best grass for alfalfa-grass mixtures, with consistently higher NDFD than other grasses suited to Northeast weather conditions.
- Alfalfa cultivar selection matters in alfalfa-grass mixtures with up to 60 percent grass in the stand.
- As low as 5 percent of any grass in a stand will increase NDFD of an alfalfa-grass mixture 1 percentage unit (grass NDFD is much higher than alfalfa NDFD).
Another challenge with an alfalfa-grass mix is determining the dry matter content and optimum harvest condition to achieve the greatest yield. Cornell has created a calculator spreadsheet that can help producers assess a stand for harvest. If the producer inputs the height of the alfalfa and the percentage of grass in the stand, the program calculates current NDF, target harvest height and approximate time to harvest. The calculator also has a weather adjustment to account for expected weather. 
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Lynn Jaynes
- Managing Editor
- Progressive Forage
- Email Lynn Jaynes
