Final cutting, weed control and fertilizer impact spring alfalfa yields
DES MOINES, Iowa, Sept. 26, 2008 – Fall and winter alfalfa field management can have a substantial impact on spring growth and next year's harvest. The timing of final cutting, weed control measures and fertilizer applications are production factors for next year's alfalfa crop, according to agronomy experts from Pioneer Hi-Bred, a DuPont business.
"Fall is the time for a thorough evaluation of the 2008 alfalfa growing season," says Gary Brinkman, Pioneer field sales agronomist. "In addition to considering fall cutting options, growers need to decide what types of fall weed management and fertilizer should be applied."
Pioneer suggests growers avoid harvesting alfalfa into the fall and consider the benefits this will have on next year's alfalfa crop.
"If growers are considering a fall alfalfa harvest, they need to take into account the potential impact for the spring crop," says David Miller, director of Pioneer alfalfa
Harvesting alfalfa into the fall potentially can damage alfalfa and increase the risk of winterkill. As alfalfa goes dormant it stores carbohydrate reserves in the root. Cutting the plant in the fall can leave it with inadequate nutrients to survive the winter.
"It's a matter of arithmetic; if a grower depletes the energy source prior to dormancy, the plant may not have adequate energy to initiate spring growth," says Brinkman. "If a grower needs to have that final cutting for added sources of feed, he or she should wait until two consecutive days of a hard freeze – 24 to 26 degrees."
Waiting until after a hard freeze allows the plant to put down all possible root reserves. Harvesting after a hard freeze will not affect winter survival or the next spring yield. However, it is important growers leave 6 inches of stubble and potentially a few strips to help catch snow for improved insulation.
Fall is also an excellent time to start reviewing fertilizer and weed management options.
"Growers should make sure there are adequate levels of fertilizer – potash specifically," says Brinkman. "A fall application or spring application is fine. Typically, the best time is after the third cutting (or fourth depending on intensity during the summer months) to help maintain winter survival conditions."
Additionally, weed management is applicable in the fall as well. Fall is an optimum time to control perennial weeds.
"It is smart to kill weeds before they get established," says Brinkman. "The majority of the time, a great spring alfalfa stand is due to applying weed control measures in the fall."
Typically, alfalfa needs to be planted approximately every three years. Intensity of harvests can play a bit of a role in the number of years an alfalfa stand can be utilized. The general recommendation, following three years of alfalfa, is to rotate to another crop for at least one year.
"Corn is a great crop to plant after alfalfa because of the significant levels of nitrogen," says Brinkman. "Some research studies have shown up to 100 pounds of nitrogen available for a corn crop. That is a huge value. Rotating out of alfalfa also breaks diseases and insect cycles."
For growers looking to replant this spring, there are a couple of important factors to consider. Soil pH should be 6.8 and adequate levels of phosphorus and potash are needed. The field should have good internal drainage or drainage tiles.
"The majority of planting occurs in the spring but is geography specific," says Miller. "Usually a targeted window of early to mid-April for a beginning point is recommended. It is better to plant on the early side of this time frame rather than later. Alfalfa will emerge in fairly cool temperatures."
Genetics also are an important aspect to look at before purchasing seed later this year or early next spring. Pioneer® brand varieties are equipped with characterization charts that offer growers information on disease and pest resistance as well as maturity and yield information.
"Pioneer still offers the traditional workhorse varieties, which are versatile," says Miller, "However, in today's industry, it is potentially more economical to invest in varieties that offer growers protection for specific field concerns rather than the conventional scout-and-spray method. For example, it may be wiser to invest in a leafhopper-resistant variety if the pest has a significant impact on two to three cuts per summer."
It also is important to prepare the seedbed, which needs to be firm and packed. Seed needs to be planted in the first quarter inch in heavier soils, and in sand, possibly a half inch.
"One of the major reasons growers see stand failure is because the seed is planted too deep," says Brinkman. "Plant alfalfa seed shallow, and work to achieve good seed-to-soil contact.
"Alfalfa is an important and valued feed source. Getting an optimum stand next spring means good fall management and proper planting techniques."
For more information on fall and spring alfalfa management, contact your local Pioneer seed sales representative. To learn more about Pioneer's comprehensive planting-to-feeding program, Silage ZoneSM, ask a Pioneer professional or visit www.pioneer.com/silagezone.
Pioneer Hi-Bred, a DuPont business, is the world's leading source of customized solutions for farmers, livestock producers and grain and oilseed processors. With headquarters in Des Moines, Iowa, Pioneer provides access to advanced plant genetics in nearly 70 countries.
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