Alfalfa offers many benefits to rotation system

By Zachary Fore
U of M Extension Cropping Systems Specialist
zfore@extension.umn.edu

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Prairie Grains is the official publication of
the Minnesota
Association of
Wheat Growers,
North Dakota Grain Growers Association,
South Dakota Wheat, Inc., and the Minnesota Barley Growers Association.

A legume, alfalfa does not require nitrogen fertilizer. Many crops yield extremely well following alfalfa, and it has been a profitable crop to grow in recent years. Following are some specific details about the benefits of alfalfa in the cropping system.

Profitability
Alfalfa has been one of the most profitable crops produced in recent years. Total production costs for alfalfa in Minnesota average from $125 to $175/A. Yields have averaged about 3 tons per acre, with the best growers getting over 4 T/A. Prices vary greatly with quality, but dairy-quality alfalfa can be worth $100/ton or more.
When calculating potential returns to alfalfa, keep in mind that yields will be lower in the establishment year. An average yield for first year direct seeded alfalfa is 1.5 T/A. The following table shows different gross returns for various alfalfa yields and prices.

Improved Workload Distribution
Alfalfa in your cropping system can help improve the distribution of your workload. As many alfalfa producers will tell you, harvest dates come about Memorial Day, The Fourth of July, and Labor Day. This gives you time to plant your other crops and harvest them with minimal interference from the alfalfa crop.

Erosion Control
Alfalfa is an excellent crop for reducing soil erosion. Alfalfa can easily reduce soil loss by 50% to 80% compared to small grains, corn, or soybeans. Erosion control is especially important on slopes and in areas with high soil loss potential.

Weed Control
Alfalfa is a competitive, perennial crop that is mowed frequently. In addition, tillage, which brings to the surface buried weed seeds, takes place less often when alfalfa is used in a crop rotation. These properties of alfalfa make it an excellent crop for suppressing weeds.

Our current cropping system of predominantly annual crops selects for certain weeds species, such as foxtails and pigweed, that are well adapted and very competitive with annual crops. Alfalfa effectively breaks the cycle of these weeds. Alfalfa producers will tell you that fields coming out of alfalfa are the cleanest fields they have. A producer recently told me, "When I used to grow alfalfa, I was able to keep wild oats under control. Since I quit growing alfalfa, I’ve got wild oats everywhere."

Disease Control
Alfalfa is an excellent crop for breaking certain disease cycles. Alfalfa is a broadleaf crop, and is not a host for scab and most other diseases which attack grass crops such as wheat, barley, and corn.

Nitrogen Fertility
Alfalfa is a legume, and is extremely efficient at converting atmospheric N that plants cannot use, to nitrate and ammonium N, which plants can use. While the alfalfa crop is growing, it is using all the N it is "fixing." However, when the alfalfa crop is tilled into the soil, a significant amount of N becomes available to the following crop. The amount of N that becomes available depends on the density of the alfalfa stand, and the amount of alfalfa growth present when the stand was tilled in.

Nitrogen recommendations for crops following alfalfa vary somewhat from state to state. However, when corn is planted following a good stand of alfalfa (4 or more plant/sq. ft.) nitrogen requirements may be reduced by up to 190 lb/A the first year and 75 lb/A the second year. Wheat nitrogen requirements may be reduced by up to 75 lb/A the first year, and 35 lb/A the second year following a good alfalfa stand.

Rotation Response
Most crops yield extremely well when planted where alfalfa was the previous crop. Weed control, disease control, and N fertility are at least partially responsible for this response. It is likely that other factors which we don’t understand at this time also contribute to this positive rotation response.
Grass crops and non-legumes perform especially well following alfalfa. For example, in a 10-year rotation study in Wisconsin, corn yields following alfalfa, even with 300 pounds of applied nitrogen per acre, were greater than with continuous corn.

Marketing and quality
Many growers are deterred from producing alfalfa because alfalfa can be difficult to market. Alfalfa can’t be just hauled to the elevator. Successful alfalfa producers know that quality is essential in marketing alfalfa. There will always be a market for high quality alfalfa. High quality alfalfa is a result of cutting at the right time, baling at the right moisture content, having weed-free fields, avoiding weathering in the field, and storing promptly and carefully. Buyers want alfalfa that not only has a high relative feed value, but also looks and smells good. Good management commands a premium in the alfalfa business.

Stand establishment
Alfalfa is usually planted in the spring (generally between April 15 to June 1 in southern MN; and May 1 to June 15 in northern MN) or late summer (generally between July 15 and Aug. 1 in northern MN; and Aug. 1 and Aug. 15 in southern MN). One advantage of fall planting is less weed competition. However, generally less moisture in the fall may mean greater potential for poor, late, or uneven emergence. There’s also the threat of frost in the fall. Alfalfa needs six to eight weeks of growth before fall freeze-up.

Oats is a common companion or nurse crop, although wheat, barley, and flax can also be used. Whether to use a companion crop depends on your objectives as a producer. To help prevent erosion, or if you need straw, forage, or grain, consider planting oats along with alfalfa. But bear in mind that a companion crop will also compete with alfalfa for establishment, and the sooner it is removed, the better for the developing alfalfa stand. Direct seeding of alfalfa without a companion crop improves the stand establishment potential of the alfalfa crop from the start.

For more specific production information, contact your county extension office. With good management, alfalfa can be grown profitably, and can improve the profitability of other crops grown in a rotational system with it.