August 29, 2013
Summer is drawing to a close and some farmers are asking if there's still time to seed alfalfa. They held off from doing it thus far in August, because it's been dry in their area of the state. In years with adequate rainfall, late summer or fall is typically the best time to establish alfalfa. Yields from late summer seeding are generally higher than yields from spring seeded alfalfa in the establishment year.
Farmers who did not have success with alfalfa that was planted in late summer 2012, should not be discouraged, says Cory Catt, forage products manager with Latham Hi-Tech Seeds at Alexander, Iowa.
The unique challenges brought by the drought last summer slowed emergence but that shouldn't be a problem this year. Seeding into dry conditions is always risky because alfalfa seed needs to absorb approximately 200% of its weight in readily available moisture for the germination process to begin, he says. In addition, the newly developing root system needs consistent access to moisture to sustain the plant and build the essential carbohydrates in the crown prior to the first frost. Catt offers the following considerations for farmers to ponder, to help them decide whether to plant a new stand of alfalfa in fall or spring.
* Weed Control: Another advantage of late summer or early fall seeding is the crop gets a jump start ahead of weeds. Soil temperatures are much higher in the late summer than in the early spring, allowing alfalfa seedlings to germinate, grow and develop a crop canopy at a much faster rate. Because of the warmer, drier soil at this time of year, diseases such as Pythium, Phytophthora root rot, and Aphanomyces root rot are much less of a concern.
* Importance of Moisture: The possibility of moisture stress during germination and seedling establishment is the main concern among farmers when choosing late summer seeding. Timely seeding reduces this risk significantly. Make late summer seeding decisions based on current soil moisture conditions and short-term weather forecasts. Near normal August and September rainfall should be more than adequate to establish productive stands in the fall.
When seeding in late summer, ensure alfalfa has excellent growth to build adequate carbohydrates prior to the first frost. Assuming the plant receives the proper amount of moisture, it should produce enough foliage to safely survive the winter.
Generally speaking, you should seed alfalfa six to eight weeks before your area receives a killing frost. For most of Wisconsin, Minnesota, North Dakota and South Dakota, prime seeding time is August 1-15. Farmers in Iowa and Nebraska can still seed toward the later part of August. In areas south of I-90, the date begins to lengthen and can continue into September depending on the year.
* Killing Frost: Another concern is the threat of an early killing frost. Again, timely seeding will minimize these risks but it is important to get the seedling off to a rapid start. This will allow adequate time for the plant to build as many carbohydrates in the crown as possible before the first frost hits and plant dormancy starts.
* Seed Treatments: Fortunately, new seed treatments are better than ever at helping set the fragile alfalfa seed for emergence success. Treatments surround the seed, helping it absorb soil moisture quickly to begin the germination process. New treatments also contain key micronutrients and growth promoters to help accelerate emergence.
* Planting Tips: When planting alfalfa, Kansas State University Research and Extension encourage producers to keep the following in mind:
Test the soil. Alfalfa grows best in well-drained soils with a pH of 6.5 to 7.5. If the land needs lime, add it before planting. Apply the needed phosphorus and potassium. Each cutting removes 10 pounds of phosphorus per acre for each ton of forage harvested, so it's an annual input.
Plant certified inoculated seed. Inoculation helps alfalfa seedlings fix available soil nitrogen for optimum production.
Plant in firm, moist soil. If possible, prepare the seedbed and plant after a rain. Tilling after a rain will reduce soil moisture. A firm seedbed ensures good seed-soil contact; therefore, use a press wheel with the drill to firm the soil over the planted seed.
Don´t plant too deep. Plant one-fourth to one-half inch deep on medium and fine textured soils and three-fourths inch deep on sandy soils. Don´t plant deeper than 10 times the seed diameter.
Plant right seeding rate. Plant 8 to 12 pounds of seed per acre of dryland, 12 to 15 pounds per acre in irrigated medium to fine-textured soils, 15 to 20 pounds per acre on irrigated sandy soils.
Beware of herbicide carryover. Check for herbicide carryover that could damage the new alfalfa crop. Areas where row crops were drought-stressed and removed for silage, a great seedbed was set up for alfalfa, but still brings a risk of herbicide damage.
Choose pest-resistant varieties. Resistance to Phytophthora Root Rot, Bacterial Wilt, Fusarium Wilt, Verticillium Wilt, Anthracnose, Pea Aphid, and Spotted Alfalfa Aphid is essential. Some varieties are resistant to even more diseases and insects.
"New alfalfa seed technologies and proper planting dates should provide confidence that your seed will be able to emerge comfortably prior to the first frost," says Catt. "Remember, when it comes to establishing a successful summer seeding alfalfa stand, emergence is the most critical component." For more information visit Latham Hi-Tech Seeds website or the blog.
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