"The decision of whether to proceed with a late summer alfalfa seeding depends on the need for good quality forage the next spring, temperature, and available soil moisture," said Karla Hernandez, SDSU Forages Field Specialist.
Hernandez lists the advantages and disadvantages of late summer seeding below:
1. Reduced weed problems due to the drier soil conditions which reduce weed seed germination. Additionally, summer annual weeds that do germinate, are typically killed by frost.
2. Time available for proper seedbed preparation.
3. Increased first year yield compared to spring seeding.
4. Possibility of seeding alfalfa following summer harvest of small grains to serve as a cover crop which will provide numerous other benefits to most farm operations.
Disadvantages of late summer seeding
1. The increased risk that moisture shortage will limit establishment.
2. Possibility of winter injury if plants do not become well established before a killing frost.
3. If soil conditions are too dry at seeding time, the seeds may germinate too late to develop enough growth and carbohydrates to be stored in the root system which increases the chances of not surviving the winter.
Recommendations for planting late summer alfalfa
If alfalfa establishes well, Hernandez said there is a good chance of beginning the next year with an established crop that can result in one or two extra cuttings.
"The risk of dry weather could be minimized by delaying summer seeding until late summer when soil moisture levels are well known," she said.
Hernandez reminded growers that fall seeding of alfalfa, on the Upper Plains, should take place by mid-August, which is approximately six weeks prior to the first killing frost. "This gives the plant enough time to crown and to store carbohydrates reserves for next season, key in their ability to overwinter," she said.
She added that planting companion crops during this time is not recommended as they tend to compete for moisture and weed pressure is usually low.