Justification: 

Oklahoma Alfalfa occupies  about 400,000 acres which generates a significant income to the state.  More than 75% of the acreage is sown with relatively recently developed proprietary varieties. Traditionally, the best alfalfas in this area have been considered moderately dormant. Varieties with a significant amount of non-dormant germplasm in their pedigree sometimes have severe winter kill. The most persistent, high yielding varieties have only slightly less dormancy than those developed for the Midwest.  

Which variety(ies) to plant is an important question alfalfa producers must resolve before establishing new stands. Literally thousands of varieties and experimental strains have been developed, and about 100 varieties are released each year. So, it is no wonder producers are not always certain about variety choice. The choice of which variety to use has an important impact on forage yields, degree of insect and disease resistance, and stand longevity, all of which affect profits.  

Alfalfa Testing Personnel: 

Personnel in the Plant & Soil Sciences Department through the Oklahoma Agricultural Experiment Station  and Oklahoma Cooperative Extension Service, conduct alfalfa variety evaluations throughout the state to assist producers with decisions related to variety choices. Normally breeders submit about 15 new alfalfas are each year for testing in Oklahoma. Currently John Caddel has overall responsibility for this activity. 

Results: 

Annual reports summarize tests results. Detailed results of evaluations are presented annually in the CAIC Variety Test Report which contains an accumulation of alfalfa tests from 15 central states and is compiled by the Central Alfalfa Improvement Conference. Summaries of our data are updated in extension publications each year.  Detailed results harvest by harvest, for each year and each testing site are available to the public upon request. 

Varieties are tested in a wide array of environments and those that perform well consistently are included in a "recommended list" if they are marketed in Oklahoma.  Other varieties that have only been tested in only 10 or 12 test-years and have performed very well, are listed apart. These "promising" varieties that have been tested for one to two years at a few sites have the pest resistance necessary for Oklahoma, and it is highly likely these relatively new varieties will continue to do well, but we consider this to be the minimum testing.  

 
HOW DOES AN ALFALFA VARIETY GET ON THE RECOMMENDED LIST? 

To be placed on this list, an alfalfa variety must consistently yield well in several tests over several years, and its stand persistence must be good. Alfalfa seed distributors should assure OSU that seed will be available in Oklahoma.  If  seed is not readily available, a variety is not recommended. 
 
High yielding varieties with long stand life have acceptable levels of resistance to the important pests in Oklahoma.  Their multiple pest resistance is necessary for good performance.

  
HOW MUCH BETTER ARE THESE VARIETIES THAN OTHERS
THAT PRODUCERS CAN USE?

 

All  recommended varieties yield much better than the average in our tests. The yield advantage is usually about 10-15% compared to old Oklahoma commons and sometimes as much as 50% better than varieties that are not well adapted.  

Much higher yields are attainable, using new proven multiple-pest resistant varieties than using old varieties or seed from unknown sources. In addition to high yields, stands of the recommended varieties normally remain productive 2 to 5 years longer than  unimproved ones. 

 

Of the 50 to 100 varieties released each year, we test those that have potential for use in the state. They are sown in replicated small plots on research stations. Each plot is harvested and weighed at every cutting for at least 3 years.  

Personnel at Oklahoma State University responsible for alfalfa variety performance evaluations make every effort to conduct the best possible tests.   Individual tests are designed to detect forage yield differences of 5 to 10% (much smaller than can be seen). Yield differences of as little as 2-3% become important as we collect data from tests at different locations and years. When accumulated over years and averaged over several sites, yield differences among the best varieties are less than 2%.  The best varieties do, however, always differ from unadapted varieties and even some of the "so-called" new varieties. 
 

Examples of Testing Sites: 

Both Research Stations in Payne County (near Stillwater and Perkins) are good representatives of alfalfa production areas in the north central part of the state. Soils are deep and somewhat variable, but by using six replications, acceptable CV's are attainable. Alfalfa test means at Stillwater are normally 6 to 8 tons/acre of dry matter with supplemental irrigagion.  At Perkins alfalfa yields 3 to 5 tons/acre with rain fed conditions. 
 
The Research Station near Chickasha, south central, represents an important alfalfa production area along the Washita River. Soils are deep but somewhat tight and occasionally saturated during extended rainy periods. This station is utilized as one of our most important testing sites because it typifies a large production area and has a good set of equipment and an experienced plot crew. Alfalfa test means normally range about 5 to 8 tons/acre of dry matter with supplemental irrigation.  
 
The Research Station near Haskell, in the eastern part of the state, is a high-rainfall, upland site. This is a good site for alfalfa tests because the station crew does an excellent job and field tours attract large crowds. Alfalfa yields well and persists well with proper liming and fertilization. When rainfall is well distributed throughout the summer, alfalfa yields normally total between 5 and 6 tons/acre dry matter per year. Potato leafhopper infestations occur in this area more often than all other testing sites. Tests at this are not sprayed for potato leafhopper control. 
 
The Research Station near Tipton, in the southwest part of the state has some of the state's best soils. Yields are normally in excess of 8 tons/acre dry matter. In a recent test yields surpassed 10 ton/acre for each of 3 years as the test average without irrigation. Alfalfa acreage is increasing in this area with an increase of dairy cattle and a decline in interest in cotton. 
 
Companies or individual who anticipate selling seed of a particular alfalfa cultivar in Oklahoma should enter it in rainfed trials as well as irrigated ones. Only about 25-30% of the alfalfa in Oklahoma is irrigated, and producers tend to be skeptical of cultivars only tested under irrigation.  Photo of a good alfalfa field. 

 

 
Announcement: 
 

An invitation is sent to all known potential developers and marketers for alfalfa in Oklahoma during late July each year for trials to be sown in September. 

Entry Fee: 

Applicants pay a fee of $350 per alfalfa entry per site for proprietary varieties or experimental strains for a 3-year forage yield test.  Fees may increase to cover increased costs, and testers will be notified in the invitation. 

Testing fees payable to the Plant & Soil Sciences Department, O.S.U., should be received along with entry forms and seed several weeks prior to establishment of new tests. 

Seed: 

A 100-gram sample of alfalfa seed per site is required. 

Participants are requested to indicate the generation of seed submitted for testing (syn 1, syn 2, syn 3, etc.) for varieties and/or experimental strains. Purity and germination information should be provided, if possible. No lime coated seed.  Participants should also indicate if seed will be shipped directly from you or via a central collection site. If seed is to be shipped from a central collection site please inform them promptly. 
 
Description of tests: Entries will be planted in plots 5 meters long consisting of five rows, 15 cm apart, with a minimum of four (usually 6) replications. Herbicides will be used to control weeds as needed. Plots will be harvested when most entries are in bud or early bloom stage, 3 to 6 times per year depending upon the site. Normally yields are recorded for each harvest during 3 or 4 years. Observations on stand persistence, disease and insect damage, rate of regrowth, etc., will be taken when appropriate. When possible, plots will be maintained for 6 years. Years 4 through 6 will be primarily for persistence observations. 
 
Miscellaneous information: Alfalfa variety tests are available for inspection at any time mutually convenient to the Oklahoma Agricultural Experiment Station personnel and outside observers. Any questions related to these tests should be directed to John Caddel.  
 
Phone: 405-744-9643 ( voice mail 24-7). 
 
E-Mail: john.caddel@okstate.edu 

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