February 5, 2010
Good quality alfalfa is the cornerstone of any dairy farm forage ration. It takes a lot of effort to figure out what management practices work best on your farm. This article contains just some of the questions and answers that have often come across my desk regarding good alfalfa management. Most of the information contained in this article came from the University of Wisconsin forage website.
How do I pick a good alfalfa variety? There are a lot of choices out there. One of the most important decisions that a producer makes is which variety to plant. Yield results for alfalfa varieties currently in Minnesota trials including the 2009 season are here. When considering varieties, the following factors come into play:
- High yield potential: Forage yield drives the economics of alfalfa production. While it may appear that two varieties perform similarly, only a 1/10 ton lower yield per cutting can result in substantially lower profitability over the life of a stand.
- Disease resistance: Multiple disease resistance is an important risk management strategy. Many diseases do not affect the health of the alfalfa plant each year, but having disease resistance can prevent catastrophe and will likely show in large yield differences at least once during the life of the stand.
- Stand persistence/winter survival: Healthy alfalfa plants that persist throughout the productive life of the crop results in higher profitability. Stand persistence is often influenced by plant health, insect management, soil fertility, and climatic conditions.
- Other selection criteria: In addition to the aforementioned items, we also have to consider factors such as forage quality, potato leafhopper resistance and maturity.
How about "cheap" alfalfa seed? You get what you pay for. University trials have used Vernal alfalfa as a standard check variety for many years. Vernal has not performed nearly as well as varieties developed in recent years. Vernal may work well for a cutting or two when growing conditions are optimum, but when stress occurs, performance lags. In medium to high yield environments, Vernal comes in at 75 to 80% of top varieties. The cost of good seed quickly becomes a minor issue when evaluating production over the life of the stand. Some "cheap" alfalfa seed is really a blend of varieties. Often in years of surplus seed production, several alfalfa varieties are blended together and sold as an unnamed seed blend. The blended seed varies by dealer and company. The problem is that you never know what genetics have been included and at what ratios. Therefore, it becomes a chance of getting good or poor quality alfalfa variety genetics in a blend.
How about applying manure to alfalfa? Manure has traditionally been targeted for use on corn acres because corn uses and needs all of the nutrients supplied by manure, especially nitrogen. In recent years, there has been a trend towards applying manure on alfalfa producing acres. We know that alfalfa CAN use all of the nutrients supplied by manure and these acres are conveniently available during the growing season. We also know that phosphorus-based manure management plans may limit the amount of manure applied to corn. Most commonly, manure applications on alfalfa occur during the fall of the terminal year before tillage since the acres will be rotated to corn production the following year.
There have been some documented cases of gross over application of nutrients that can cause some environmental hazards. Over application can also cost the producer money due to unnecessary additional fertilizer purchases. Applying manure prior to alfalfa seeding breaks traditional thought in that manure nitrogen is being applied to a legume crop, which fixes its own nitrogen. However, such applications can result in significant phosphorus (P) and potassium (K) contributions for alfalfa establishment and in subsequent production years. The application of manure to alfalfa prior to seeding should only be used where the crop is direct seeded or the companion crop is removed as forage. Applying high rates of manure where the companion crop will be harvested as grain often results in significant lodging of the crop.
Manure can be applied to established alfalfa, if we follow a few guidelines:
- Manure applications need to be made immediately after alfalfa harvest to reduce the risk of plant damage from both salt burn and wheel tracks.
- Skip applications if soils are wet to reduce soil compaction.
- Do not apply more than 3000 to 5000 gallons per acre of liquid manure or about 10 tons of solid dairy manure.
- Keep in mind that burn potential is a function of manure ammonium nitrogen and salt content. This can vary with manure type and source.
- Finally, be sure to apply manure uniformly across the field.