Winter Alfalfa Management
Warren C. Thompson
National Forage Specialist: America’s Alfalfa
When is it safe to take a fall/winter alfalfa harvest without causing irreparable damage to the crop in years to come? This question comes up under many and varied situations such as the big dollar value for cash-hay or the weather report looks favorable for good hay making conditions. It could be that there is a shortage of hay due to a dry summer or overstocking. Situations like these and others occur nearly every year so let’s see if I can help unscramble this situation.
The biggest threat to harvesting hay in the fall is drying conditions. The long time problem is much more complex. In the fall and early winter, it takes time to build food reserves in the roots and crowns of the plants to produce healthy plants that survive the winter and continue to produce for years to come. When alfalfa is harvested inside the six weeks window, the plants do not have sufficient time to build the reserves. This weakens the plants and they never seem to recover.
Once growth is terminated and that takes about two days of 24-26 degrees (F) for two consecutive nights to shut the plant down, it is safe to harvest. After wilt (usually 2-4 days) it is safe to harvest and when harvest is made before massive leaf drop, the feed is equal to the harvest quality prior to wilt and leaf drop. (See photo below)
In several tests around the USA, we have found that the following year’s yield is normally reduced equal to the weight of forage removed during the fall harvest. But most farmers are willing to take that chance when the price is high and/or the needs great.
So here is the recommendation that I have lived with for years: If you seriously need the feed this winter, go ahead and harvest this fall following the above schedule. Keep in mind that the likelihood of ideal hay curing conditions during this period is poor at best. Actually, silage is a better bet since dry-down time is cut in half or more.
If you are growing the grazing tolerant varieties, grazing can be a best bet for this harvest. Just keep in mind that if you do graze the alfalfa at this season, bloat can be a problem. So follow the same guidelines of grazing entry that are standard for the rest of the season. Besides, at this period, cattle are likely going to be hungry for some fresh grazing and are very likely to over-eat. If there ever was a good time for free access to dry hay and Poloxolene (Bloat Guard) this is it.
Should you graze ‘mechanical harvest-only’ varieties, you better pull the animals when the soils are even the least bit wet and treading damage is likely to occur. Also on these varieties, (especially in the colder-climate areas), be sure to leave some excess crop residue to help resist ice-damage and smothering.
Our America’s Alfalfa harvest tolerant varieties are performing quite well in abusive treatments and splendidly under ideal conditions. These varieties include AmeriGraze 210+Z, AmeriGraze 401+Z, AmeriStand 403T, Alfagraze and AmeriGraze 701. Why? These varieties store more carbohydrates and produce more crown buds late in the season. But for goodness-sakes, don’t try to kill them by abusive treatments. Next year’s yield will be lowered and if you thin some areas, weeds can become a real problem next summer.
Leave some stubble for winter protection. In the areas north of I-40, to I-70, leave 4-6 inches of stubble. Further north, stubble height of 6-8 inches is better. In the southern regions, leave a four-inch residue for quick spring growth even though winter damage is usually no big issue.
Fall/winter is a great season to apply top-dress fertilizers. There was a time when it was thought that fall applied potash would leach during the winter months. On very sandy soils, this has been confirmed in recent years. But even on these soils, leaching losses are minor compared to the importance of getting the fertilizer on at this season to improve winter survival and following year’s production. Besides, applying at this time is usually more convenient and less damaging to plants and soils.
Fertilizer prices are usually lower and more accessible in the fall and winter. Also, spreader trucks and fertilizer buggies are more likely to be available. What fertilizers should you use? Go to your most recent soil tests to find the ratio recommended for each field and you decide what the production you want and fertilize accordingly. The key fertilizers are phosphate and potash and a maintained pH level of 6.5 and above. Where pH has been a problem, an annual application of Boron is nearly always recommended. In some areas, sulfur and magnesium are routinely recommended. Since alfalfa produces it’s own nitrogen, seldom (if ever) is nitrogen needed as part of the top dress program.