Wet conditions recently may have thrown off your hay harvest schedule or left you with ruined hay on the ground. With forage being tight this year as we head into winter, a late alfalfa cutting may be on your mind, but we need to take into consideration the impactions a harvest in later September or October have for next spring.
Typically alfalfa needs six weeks of uninterrupted growth before the average first frost to winterize. The winterization process itself, takes three weeks, but having a total of six weeks helps to mitigate risks by allowing the alfalfa to move stored reserves to the roots and become acclimated to changing temperatures. The added three weeks before winterization acts as insurance for early frosts as well. Allowing alfalfa to successfully winterize is key to having productive stands next spring and reducing long term losses in your alfalfa stand.
Stress during the season also plays a role in the winterization process. Environmental stresses such as; drought, heat, hail, or frost cause slower regrowth and shorter stands in season. Even the amount of times we cut stands and the age of the stand are stress considerations. Therefore, if you are trying to push the six week rule, remember that alfalfa that has been heavily stressed throughout the season or older stands would benefit from having uninterrupted growth to complete the winterization process.
When planning your last cutting for older or stressed alfalfa stands, keep in the mind the dates for establishing fall alfalfa as a guide to your last cutting. The window for growth leading into fall ranges throughout the state of Nebraska. Typically for northeast Nebraska we recommend having the last cutting wrapped up and stands beginning the winterization process by now. If we do push the harvest window later, remember that these fields harvested later into September or early October will have a slow start next year and may have issues overwintering if the stands are stressed or older.
When cold temperatures do come to call, the nature of the freeze we get will have an impact on management options. A non-killing frost ranges from 32-30°F, with a killing frost occurring at 29-24°F for 4 to 6 hours. The determination between a non-killing and killing frost is crucial when making management decisions, especially cutting or grazing.
In the case of non-killing frosts, typically we can see a deterioration at the tip of the alfalfa plants, with wilted and slightly curled leaves. If the light frost occurs for an extended period you can see some bronzing on the leaves as well. It is important to note that these alfalfa plants will continue to grow, but their quality will decrease as fall continues. If cut following a non-killing frost regrowth will continue to occur at the crown buds and the plant will begin to utilize stored sugars, possibly affecting winter survival and spring vigor.
Once the hard frost occurs the stand can be cut. Harvest needs to take place shortly following the killing freeze to maintain as much of the nutritive value as possible. Bloating can be a risk when stands are used for grazing. Remember this should really only be an option if the need for forage will outweigh harm to the stand. Damage to the stand and increased exposure to environmental conditions can negatively affect the stand over winter and into the spring.
-Ben Beckman is a beef systems Extension Educator serving the counties of Antelope, Cedar, Knox, Madison and Pierce. He is based out of the Cedar County Extension office in Hartington. You can reach him by phone: (402) 254-6821 or email: ben.beckman@unl.edu