IN SEARCH OF HIGHER
Alfalfa (Medicago sativa) has fueled the dairy industry for many years. Over time there have been great strides made in breeding alfalfa varieties with comprehensive disease resistance, winterhardiness, and faster regrowth potential. Fall dormancy rating is no longer as strongly correlated to winter survival and persistence like was once the case. As a result, the genetic potential for higher alfalfa yields has increased, but in the upper Midwest there has still been a very dramatic shift to grow more silage corn. In part this is because it results in higher and more stable yields from year to year.
A part of the issue simply relates to the fact that alfalfa is a perennial and corn is an annual. As such, corn allocates resources for the short-run while alfalfa does the same for the long haul. Further, seed companies divert a lot more of their resources into breeding corn than breeding alfalfa. Can alfalfa compete with corn silage from a yield perspective or is the current production as good as we can expect---while still harvesting dairy quality forage?
Alfalfa dry matter yield results from the University of Wisconsin’s performance trials are presented in Table 1.
There are several readily apparent conclusions that can be drawn from a quick look at these data. They are:
· Location matters. Where your ancestors decided to drop anchor or buy real estate has a big impact on the quantity of crops you harvest. Length of growing season, soil type, and topography are a big part of the equation no matter what management decisions are made. The Arlington location typically provides the best combination of productive soils and a long growing season. Even the old variety ‘Vernal’ has yielded as much as 8.50 tons of dry matter at Arlington.
· Weather matters....a lot. Regardless of what we do, a dry, wet, or cool growing season (or even month) can doom an alfalfa crop. Note the 2007 seeding at Chippewa Falls where the dry conditions on a somewhat sandy soil in 2008 and 2009 resulted in only about 3.0 tons of dry matter harvested per year, but in the third production year (2010) a total of 5.50 tons was achieved from the same trial. For many alfalfa fields, four harvests are taken each year. In effect, this is the equivalent of four separate growing seasons. It becomes difficult to recover yield from a two to three week dry spell when the “growing season” for any one cut is only about 30 days.
· A total management program is needed if you expect to maximize alfalfa yield. This gets to be an old story, but it’s pretty clear that many current alfalfa fields are deficient in potassium and sulfur. Either nutrient can have a large impact on yield. Ditto goes for insect pests like potato leafhopper when left unchecked. Finally, behind the average numbers in Table 1 is a lot of genetic variation. Take advantage of this fact.The potential is there! A total of ten varieties yielded over 10 tons of dry matter per acre at Arlington in 2009 and 2010. This is the equivalent of not just a good corn silage yield, but a great one. Perhaps an argument can be made that 10 tons of alfalfa per acre is unattainable on most production fields. Fair enough. What can’t be argued is that the genetic potential to achieve such a yield doesn’t exist. It obviously does.
For more information contact Mike Rankin