This is the time of year I usually have an article about cutting and harvesting alfalfa in the fall. In the past, producers have been advised to cut hay 4-6 weeks prior to a killing frost. (The average first frost date for the Lovelock area is Oct. 1-10.) This advice is based on the fact that alfalfa plants need time to store carbohydrates in their root system prior to a killing frost in order to prevent winter kill. About 50 percent of the stored carbohydrates are used during the winter for plant survival. The remaining carbohydrates are available in the spring for initial herbage growth.
However, some experts now question the usefulness of that recommendation. The old recommendation is very conservative and will assure the best chance of reducing any winter kill or injury, but with new disease-resistant and winter-hardy alfalfa varieties, coupled with today's high hay prices, many growers are willing to be more aggressive in their fall harvest management. Hay growers, and particularly commercial growers, seem willing to take on more risk in a marketplace where premium alfalfa can easily sell for $200 to $250 a ton.
But, before you decide to make that last cutting you should ask yourself some important questions.
- How old is the stand and how long do you want/need to keep it? If your goal is to keep the stand for five or more years, fall harvesting may be too risky for you. If you plan to keep the stand for three or four years to capitalize on the benefits of shorter rotations, fall harvesting is a viable option to maximize yields.
- What is your feed inventory or current prices for high quality hay? Do you need high quality feed? Fall alfalfa is usually some of the highest quality alfalfa of the season.
There is still risk involved with harvesting during the "fall critical period," which is usually defined as mid-September to mid-October. This is because harvesting during this window can still result in inadequate time for regrowth to restore root reserves prior to a killing frost. But the critical period becomes less important as cutting frequency decreases. For example, a third cutting in September is safer than a fourth cutting in September. There is no need to wait for a killing frost. In fact, it's usually better not to wait. A killing frost will induce leaf drop and quality and yield decline. Dormancy is a response to the combination of decreasing day length and temperature. Once October arrives, cut when weather and your time permit.
Younger stands are less susceptible to winter injury than older stands, because young alfalfa plants are healthier than older plants. Thus, younger stands are less likely to be injured by fall cutting. Healthy stands seeded to winter hardy varieties in spring should be very tolerant of October harvesting. If the stand is getting toward the end of its useful life, there's little harm in being aggressive.
Alfalfa uses a lot of potassium, and its winter survival has been linked to soil K levels. Fields with medium or low levels of K will be less tolerant of fall cutting. Also, Alfalfa fields that are waterlogged now or at any point during the season are less tolerant of fall harvesting.
Some forage experts also recommend taking at least one cutting during the growing season at 50 percent bloom. Doing so may reduce the quality of that cutting but it will also reduce the risk associated with fall harvest compared to making all cuttings at the late bud or first flower stage.
Leaving six inches of stubble in the field in the fall can also help catch snow which serves as an insulator against subfreezing winter temperatures. Growers should avoid fall-harvesting fields that have a history of frost heaving or of accumulating little snow cover.
Grazing is a great option for fall harvesting alfalfa. Patterns of use by grazing animals often leave better stubble for catching insulating snow. But don't graze when the soil is wet, lest stand damage occur. Follow bloat precautions if grazing pure alfalfa, especially right after a killing frost.
In the end, fall harvest decisions will depend on economic considerations/goals of the operation and how much risk a grower is willing to take.
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