Time to Wrap Up the Last Cutting of Alfalfa

By Mark Sulc, Ohio State University Extension

It is time to take the last cutting of alfalfa and red clover in Ohio. Cutting this week will allow plenty of time for the stand to regrow and store energy and proteins in the taproots, which are important for winter survival and early growth next spring.

It may be tempting to wait to cut the alfalfa because of low yield due to the recent dry weather, in hopes that rains will come and more growth will occur. But delaying the last cutting of alfalfa to late September into mid-October can carry serious risk to the health of the stand. Cutting later will interrupt the process of storage of energy and proteins in alfalfa taproots. When cut during the fall rest period, the plants will regrow and utilize precious taproot energy and protein reserves without sufficient time to replenish them before a killing frost.

Fall cutting may not result in real obvious stand loss, although that can occasionally happen. The more common occurrence is for fall-cut alfalfa stands to suffer some loss of vigor and yield next year that is not so obvious. One could only see such loss of vigor and yield next year if side-by-side comparisons were made within the same field, where strips of alfalfa are cut or not cut this fall. Often, the yield gained by cutting during the fall is lost in reduced yields the following year.

If stands cannot be cut this week or are not worth cutting due to low yield, a LATE fall harvest is probably a safer alternative than cutting next week and into to mid-October, By LATE HARVEST, I mean as close as possible to a killing frost of alfalfa, which happens when air temperatures reach 25 F for several hours. This often does not happen until sometime in early November in Ohio. BUT I recommend a late harvest option ONLY IF the soil is well-drained, the stand is healthy, a variety is planted that has excellent winter hardiness, and the soil has good fertility status.

If you cannot cut alfalfa by this week, waiting to cut near the killing frost will prevent the late fall regrowth that “burns up” energy reserves. This will reduce the risk of loss of vigor next spring.

A fall harvest after a killing frost (end of October, early November) is relatively safe IF the soil is well-drained and there is no history of heaving on that particular soil. Without residue cover, the temperature at the soil surface will fluctuate more, so the potential for heaving injury is greater, especially on soils with less than perfect drainage.

I am often asked whether leaving a large amount of fall growth can harm the alfalfa stand in the winter. The fear is that the alfalfa will “smother itself out”. I have let pure stands of alfalfa go into the winter with a lot of growth, even more than we see this fall, and I have never experienced a problem or seen the crop “smother out”. So if we do get a lot of growth this fall, and you don’t need the forage, it won’t harm the alfalfa stand to let it be and not cut it.

Fall management of alfalfa is one of the few controllable factors that will potentially influence the health of your alfalfa stand next year. It could play a determining role in how much yield you get next year.

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