Don Myers
1. Should I make forage seedings in spring or late summer?
Summer seeding of alfalfa is a rapidly increasing practice. Recent surveys indicate that approximately 40 percent of the alfalfa seedings in Ohio are now made in August. The remaining alfalfa fields (60%) are seeded in spring. Approximately half of these spring seedings are made without a small grain. The majority of the other legume species (Red clover, birdsfoot trefoil, etc.) are spring seeded.
There are several reasons for the rising interest in August seedings of alfalfa. The seeding is usually made following a small grain crop. After the small grain is harvested and the straw removed, the seeding operation is performed. Thus, a summer seeding allows a farmer to maximize the yield of his small grain without harming the establishment of his forage crop. Another advantage to an August seeding is that weed competition is often much less at this time than in the spring. Finally, summer seeding of alfalfa usually works well into the management scheme of most farms. During August the producer is normally less pressed for time than in the spring.
Many farmers are choosing to make part of their seedings in spring and part in summer. In this way, they can distribute their labor commitments and also the risk of failure, should uncontrollable factors (weather, insects, disease, etc.) occur. In general, if the seedings are properly done and if the new stands are then properly managed, the chance of success should be equal with spring and summer seedings of alfalfa. Other legume species are normally better adapted to spring seeding.
2. When should lime and fertilizer be applied to make necessary corrections prior to seeding alfalfa?
If the pH is lower than 6.2, lime and fertilizer should be applied at least 6 months prior to seeding.
3. How come my no-till forage seeding resulted in a poor stand?
There are a number of reasons that this could have occurred. As you search for the particular problem(s) that was responsible for your poor stand, we suggest you carefully reexamine the following aspects of your forage program:
(1) Soil fertility - What was the soil pH and the residual levels of the major nutrients at the time of seeding? Whenever the soil pH is too acidic or the P level is too low, corrections need to be made well in advance of seeding. Because the fertilizer nutrients must be surface applied in a no-till system, they need to be added at least 1 year, and possibly 2 years, prior to seeding.
(2) Soil properties - Are there problems with drainage or compaction?
(3) Existing vegetation - Did you make the seeding into an aggressive perennial?
(4) Herbicide program - Could there have been damage to the stand from herbicide residuals?
(5) Seeding - Was the seeding timely? Was the seeding made shallow enough? Did you get an acceptable seed/soil contact with the no-till drill?
Even when a producer has paid close attention to the above details, poor stands
can still occur. There are many factors over which we have little control (weather, insects, diseases, etc.).
4. Can a no-till seeding of alfalfa be made into old sod in the spring?
Yes, some producers have been successful with spring seedings of alfalfa into old sod. In general, it is too difficult to attempt to kill the sod and seed during the spring. Therefore, we recommend that the old sod be killed the preceding fall with a non-selective herbicide (Roundup). The killed residue should be left on the soil surface over winter. Seeding can then be done the following spring during mid to late April.
Even though some producers are successful with such spring seedings, a more reliable method is to kill the sod during summer and then seed sometime during August. Therefore, when possible, a farmer should seed alfalfa into sod during the summer.
5. When should alfalfa be fertilized?
We recommend a split application of K: 1/2 should be applied following the first cut and 1/2 following the last regular cut (approximately mid-September). If, however, you can only apply K once, then a mid-September application is preferable.
A single application of P is adequate. This can be applied after either the first or the last harvest of the year. If desired, P can be split applied with K.
6. Why the high fertility recommendations on CRP forages?
The Conservation Reserve Program (CRP) makes no provision for fertilizer application following seeding. Therefore, if adequate vegetative cover is to be maintained in CRP fields for the 10 year period mandated by the program, some minimum level of soil fertility is needed prior to seeding the vegetative cover. This minimum soil fertility level has been determined to be 30 lbs./A P (Bray PI) and 220 lbs./A exchangeable K.
The Natural Resources Conservation Service (NRCS) oversees all CRP fields; it must assure the persistence of a vegetative cover that is adequate to retard soil loss. Thus, SCS is making fertilizer recommendations for CRP fields based upon the above minimum levels. The recommendation for soil test values between 30 and 90 lbs. P/A and 220 and 400 lbs./A exchangeable K is to apply 20-40-40 as a starter fertilizer at seeding.
If the soil analysis for a CRP field is extremely low and thus a large quantity of fertilizer appears to be needed to raise the soil fertility to the minimum CRP levels, we suggest that another soil sample be obtained. By definition, CRP land was to have been recently planted in a row crop. it seems improbable that a row crop could have been grown on a soil having such low fertility.
7. Does the nitrogen production gained by including a legume in a pasture seeding justify the extra seed cost and P & K need? What if it's CRP ground?
Yes. Including a legume eliminates the need for nitrogen fertilizer, thereby reducing input costs. We always recommend that a legume be included in a pasture mix so that both the quantity and the quality of the pasture mix are maintained.
Vegetative cover must be maintained on all CRP (Conservation Reserve Program). Even though the monetary return may be less on a CRP field, we suggest that a legume be seeded along with the grass because it will add increased vigor to the forage stand. In addition, legumes can help improve soil aggregation and allow easier root, water, and air penetration of the soil.
8. Is it economical to apply 150-200 pounds of nitrogen to tall grasses? When is the most efficient time?
There should be an additional 20 pounds of dry matter produced for each pound of N added. This extra dry matter will subsequently be converted into animal product. As a general rule of thumb, 20 pounds of dry matter will equal one pound of beef. Therefore, one pound of N fertilizer should result in one additional pound of beef. To determine whether or not this is an economical practice, you must compare the cost of the N fertilizer with the value of this additional beef production.
If 150-200 pounds of N are applied, we recommend a split application - 1/2 in early spring prior to the initiation of new growth (March to early April) and 1/2 in early summer (mid-June). The greatest response to N fertilization will occur in early spring. Therefore, if only a single N application can be made, an early spring application will be most efficient.
9. What specific inoculum should be used for alfalfa?
Rhizobium meliloti is the bacterial species that should be used to inoculate alfalfa. In farm supply stores, this bacterium is normally sold as an alfalfa/clover (combination) inoculum.
10. How can one control weeds in alfalfa?
A weed control program must be able to selectively remove problem weeds from a field without causing serious injury to the alfalfa itself. In deciding on a plan for weed control, you must ask yourself several questions so that you can identify the specific weed problem that you are trying to deal with. First, are the major weeds grasses or broadleaved species? Are they summer or winter annuals? Are they summer or winter perennials? Second, one must know whether the field is an established stand or a new seeding as approaches for weed control will be different in these fields. Finally, consult the forage chapter of the current edition Ext. Bull. 789, Weed Control Guide for Ohio Field Crops, for a rating of the relative effectiveness of forage herbicides on the major weeds you have identified, and using this information, formulate a weed control program. Specific information concerning rates and methods of application for the herbicides are contained in the Weed Control Guide For Ohio Field Crops.
There have been a few recent changes in herbicide recommendations for forages. Poast is now labeled for use with alfalfa, both in new stands and established stands. In addition, Dinitro is now illegal to use.