Now is a good time for growers to assess stands of alfalfa
Wednesday, October 23, 2013 5:00 PM
LOVELOCK - Now would be a good time for farmers to assess stands to determine if any limestone, nutrients or reseeding plans are necessary.
After a year of limited irrigation water, producers should evaluate the density of the stand and determine if soil fertility, diseases or other stresses might have affected this past year.
Over time, alfalfa plant density lessens. Both forage yield and quality are directly related to stand density.
In the past, alfalfa stands were evaluated by using plant counts to determine the number of plants per square foot (with less than 3-5 plants per square foot indicating the field should be replaced) because these stands usually yield less than four tons per acre.
Furthermore, forage quality declines as weeds invade open spaces between plants.
The problem with using plant counts to assess stands is that all plant crowns are counted equally. However, a small weakened plant is not nearly as productive as a large healthy plant.
Research in Wisconsin has demonstrated that the number of stems per square foot is a better reflection of productivity than is the number of plants. Results showed that fields with 55 or more stems per square foot (measured at six inches of regrowth) produced maximum yields and that fields with fewer than 40 stems per square foot were not profitable and warranted replacement.
Although, the matter of when to remove an alfalfa field is primarily an economic decision. The anticipated yield, quality, and price of alfalfa produced from a new field must be compared with that of the existing stand. Remove a stand when its productivity has declined to such a degree that net profits would be greater if the alfalfa were removed and a new crop established.
However, producers in Nevada have to also consider if there is, or will be, adequate water to establish a new crop for the upcoming year.
When faced with a depleted alfalfa stand, growers have two options: stand extension and stand replacement.
Continue to harvest a poor alfalfa stand.
Inter-seed another forage plant.
Over-seed with alfalfa.
Replant alfalfa after removing old stand (produce back-to-back alfalfa).
Remove stand and rotate to another crop. Factors to be considered when deciding which option to pursue include pressure from diseases, pests, and weeds; rotation requirements; total acreage and type of forage desired; and the projected status of the alfalfa hay market.
Prolonging stand life is unwise if disease pressure is severe. Likewise, if fields are heavily infested with rodents or difficult-to-control perennial weeds, remove the stand.
If you have insufficient forage acreage, consider inter-seeding, over-seeding, or replanting alfalfa after alfalfa. High hay prices are another incentive for extending stand life. However, continuing to harvest a poor alfalfa stand is not usually a viable option. In general, intermountain alfalfa stands remain in production for too many years rather than too few.
Thickening a stand is difficult because alfalfa does not readily reseed itself, and over seeding is not successful because of competition with existing plants and auto-toxicity (a process in which established alfalfa produces a chemical that can reduce establishment and growth of new plants).
Inter-seeding with grasses or small grains is an option. Inter-seeding may preclude the need for an herbicide and alfalfa weevil treatment. Also, yields of mixed alfalfa-grass fields are frequently over one ton higher than those of older, pure-alfalfa stands.
The economics of inter-seeding are market related and depend on the price differential between pure alfalfa and an alfalfa-grass mixture. The market for mixed hay is primarily for horses, but mixed hay is also fed to cattle and dry cows.
The price difference between pure alfalfa and alfalfa-grass mixtures depends on the visual appearance of the hay and the strength of the horse hay or stock hay market. Alfalfa-grass hay sometimes sells for as much as pure alfalfa hay in areas that have developed a strong horse hay market.
Finally, if a soil test has not been taken in the past couple of years it would be advised to get one taken immediately. Some changes to soil properties, such as, soil pH, nutrient levels and salts removal, can take time. Therefore, fall is a good time to make these adjustments to soil characteristics so your plants will have better growing condition come next spring.
So, get out there and take a good look at your alfalfa fields and hope for a wet winter.
Source: Intermountain alfalfa management, Pub. 3366, University of California Division of Agriculture and Natural Resources, Steve B. Orloff, Harry L. Carlson.