The alfalfa evaluation program within the Plant & Soil Sciences Dept. at OSU tests the performance of alfalfa varieties that may be marketed in the state. Our purpose is to help alfalfa producers decide which varieties to consider and to assist marketers to choose varieties for this area. Normally 10 to 20 new alfalfas are submitted annually for testing in Oklahoma. We also include in these tests some varieties that are well tested to give a sound basis of comparison among varieties.

The table below summarizes facts about the best varieties in current tests. Those wanting detailed information about alfalfa variety performance should visit http://alfalfa.okstate.edu/var-test/alf-var.html on the Internet. Currently, detailed results for the 1999-2003 harvest years in Oklahoma are available and can be printed from that site. If anyone desires older data, email the authors at caddel@okstate.edu

Some of varieties listed in Table 1 are well-tested and have had consistently good yields. That is, they have been in several tests, representing diverse alfalfa production areas in the state. A couple (HybriForce-400 and Good As Gold II) look good in limited testing and will probably have adequate testing by the end of this season to recommend.

• OK 49 is a relatively old (1990) variety developed by the Oklahoma Ag. Experiment Station for Oklahoma that has maintained its high yield and persistence.
• Magnum V, released in 1995, has been one of the highest yielding and well-tested varieties for this area. It has consistently produced high yields in diverse locations.
• Garst 6420 was released in 1998, and is distributed in Oklahoma by Garst Seed dealers. It is another in a long line of good varieties marketed by this company.

The cost of alfalfa seed is too often a determining factor for deciding which variety to buy. Before making a decision based on seed price, consider some of ramifications of the choice.

Generally, cheap seed is a poor way to save on the cost of alfalfa production. Cheap seed is frequently VNS (Variety Not Stated). So, immediately you know that the seed was probably not selected for this area; it is just what is available.

Seed of proven varieties normally costs more than VNS seed because much expense went into the selection of the genetics of the variety. The seed was produced under carefully controlled conditions and it was conditioned, treated, bagged and shipped under carefully controlled conditions. And they are worth more to the alfalfa producer.

The yielding potential of alfalfa varieties varies greatly. Some varieties will not produce high yields, no matter how well it is treated. Other varieties consistently produce high yields of high quality hay.

Table 2 shows that there may be little yield difference between the most expensive proven variety and some of the less expensive proven varieties.

On the other hand, there is nearly always a big difference between the yield of VNS and proven varieties - as illustrated by a yield loss of 10% to 30%. Frequently the proven varieties persist longer which again changes the economics of seed.

Table 2 is broken into several parts that may not be apparent at first glance.

The first major break has to do with the site.

High Yield Potential - Good Soil and/or Irrigated.
Rainfed sites and shallow soils.

The second break out is sowing rate -

Same rate for all seed sources (top).
Sowing rate differing according to seed quality (bottom).

Within each of these groups is -

Proven variety, priced high (example $3.50)
Proven variety, priced moderately (example $2.50)
VNS of high quality and reliable source (example $1.75)
VNS of poor quality and unknown source (example $1.25)

The different qualities of and source of seed results in nearly a three-fold difference in cost of seed per pound. This difference can be canceled by sowing less seed per acre. A good productive stand can develop from only 10 pounds of seed per acre of good, clean seed planted in a good seedbed.

If the stand only last three years, there is still a big difference in cost of seed on per acre per year. The difference becomes much smaller when seen as cost of seed per ton of hay produced.

If the seeding rate is reduced, seed cost per ton of hay for proven varieties is less than the VNS seed in only three years. At the high seeding rate after seven years (and most VNS stands will not be productive for seven years), there is little difference in cost of seed on per ton of hay basis in the highly productive sight.