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," says Schoper. "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 you 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 and potassium 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 you 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 3,000 to 5,000 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.
Source: University of Minnesota