Alfalfa is the most productive and widely adapted forage species. Idaho alfalfa acreage was 1.04 million acres in 2012 (NASS 2013) which was up 40,000 acres from 2011, and down from about 1.25 million acres in 2003. Production was 4.16 million tons with an estimated gross value of $799 million in 2012, third in the US. Forage yield and quality vary widely across Idaho environments and operations. The Idaho Agricultural Experiment Station (IAES) conducts alfalfa variety performance trials at several sites in southern Idaho including the Kimberly Research and Extension Center. Over 300 alfalfa varieties are available to US producers, and these performance trials are designed to assist producers in choosing their varieties.
Alfalfa varieties are tested for forage yield for at least three production years on irrigated sites. All trials are planted as randomized complete block experiments, with four or six replications. Trials receive adequate fertilization, irrigation, and weed control for optimum production. A 2011 trial was planted in May 2011 at the Kimberly R&E Center, and in August at the Brigham Young University-Idaho farm in Rexburg, ID in cooperation with Greg Blaser, agronomist BYU-Idaho. A 2012 trial was planted in May 2012 at the Kimberly R&E Center, and two trials in Northern Idaho with Jim Church and Ken Hart. Seedling-year production results are limited in value for predicting future performance.
The seed industry contributes significantly to the variety trials. Besides donating the seed, they pay a significant fee to offset our costs of doing the work. The Plant, Soil, and Entomological Science Department of the University of Idaho also contributes significantly in salary and equipment—the 5-ft forage harvester purchased for our use costs as much as a big machine.
Yield is the most important economic factor for alfalfa profitability. Average yield over a period of years and at several locations is a good measure of disease resistance and plant persistence. Generally, the top yielding 1/3 of the varieties are not significantly different for yield. University trials offer neutral testing of varieties but will not test blends--if the source is different every year, there is no point to test it. Industry data can be valuable because it usually is for a longer period of time, but you should ask for the complete data from the trial, not just a section of it. Avoid data with only one year or a single harvest.
Forage Quality--Plant more than one variety, especially if you have large acreage and are seeking dairy-quality hay. Varieties with different maturities will reach the cutting time up to about a week apart, allowing you to cut more hay at the pre-bud or bud stage. Harvesting at the correct maturity and agronomic practices (proper irrigation and weed control) has a larger effect on quality than does variety.
Variety selection is important but not the only factor affecting yield and quality. Soil fertility management, irrigation management, weed control, and harvest management may affect your profit more than variety. However, almost all newer varieties will yield more and be more resistant to pests and diseases than the old public varieties!
of Variety Information
University of Idaho Forage Extension: http://www.extension.uidaho.edu/forage/
Hay and Forage Association: http://www.idahohay.com/
Alfalfa Alliance's: http://www.alfalfa.org
American Alfalfa Improvement Conference: http://www.naaic.org/
University of California, Davis: http://alfalfa.ucdavis.edu/
For information regarding the Idaho Hay and Forage Association, email