What should you do with fall alfalfa? Leave it? Cut it? Graze it? Each of these options can be correct under appropriate conditions. Making the best decision requires balancing the associated rewards and risks with each option. In the past, producers have been advised to cut hay 4-6 weeks prior to a killing frost (The average first frost date for most of Northern Nevada is October 1st- 10th). 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 winterkill or injury, but with new disease-resistant and winter-hardy alfalfa varieties, coupled with today’s 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 $250 - $350 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 5 or more years, fall harvesting may be too risky for you. If you plan to keep the stand for 3 or 4 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 of alfalfa, without the risk of winter injury. Grazing alfalfa in late summer and autumn provides a high-quality pasture for preconditioning calves, putting body condition on bred cows and flushing ewes. Alfalfa regrowth is a rich source of protein, energy, vitamins and minerals. However, due to the potential for pasture bloat, ranchers should always be cautious when grazing alfalfa-dominated hayfields.
Fall grazing presents some specific challenges. Ruminant livestock grazing lush pastures of alfalfa, clovers and small grains are prone to a condition called “frothy bloat”. Rapid digestion of forage containing highly soluble proteins results in a stable foam, which prevents rumen gases from being expelled by normal eructation (belching).
How do you prevent or control bloat? A number of products are promoted as “bloat preventative”, including specific alfalfa varieties, ionophores and mineral mixes. However, the most studied and effective treatment is Poloxalene (Bloatguard), combined with good animal health practices such as mineral supplementation and vaccinations.
Livestock should also be fed dry roughage before turning out on alfalfa fields. The alfalfa should be dry, and grazing should be continuous rather than frequent corralling or movement. Paddock rotation should occur in the afternoon. The animals should be monitored multiple times daily initially and daily thereafter. The intake of Poloxalene should be monitored, daily as intake will vary among animals. However, do not 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.
Sources:
Watch For Bloat When Grazing Alfalfa This Fall, Dennis Cash and Rachel Endecott from Montana State Extension.
What To Do With October Alfalfa, Bruce Anderson, Nebraska Extension Forage Specialist.