Factors That Impact Alfalfa Reseeding Success
Sep 28, 2010
Question: I have an alfalfa field that’s on a hillside that I want to reseed back into hay as this is the best way to manage this highly erodible ground. My plan was to seed it with some wheat to get some quick plant establishment along with the alfalfa in the grass seeder on my drill. A friend of mine told me I shouldn’t plant alfalfa back in--that I need to put the ground in straight wheat for a year because of some toxin alfalfa leaves in the ground, which will inhibit germination of the new seed. What do you think?
Answer: New alfalfa seedlings can die when seeded into an established alfalfa stand. This is known as autotoxicity. Autotoxicity can result in poor germination and reduced vigor of alfalfa seedlings replanted into destroyed (tilled or herbicide plus no-till) alfalfa fields without rotation (Volenec, Purdue). These negative effects come mainly come from the leaves and flowers. To reduce your risk, it is recommended that you wait at least one year before reseeding alfalfa into the field. If waiting one year before reseeding is not possible, there are a few things you can do to reduce autotoxicity. Tillage can help with this situation; however, your highly erodible fields may not allow that. If you are planning to no-till the new stand in, waiting four weeks after the old stand has been killed will help reduce autotoxicity. Rainfall and sandy soils tend to leach the toxin sooner which again reduces the autotoxicity. Purdue University has a great extension bulletin with more specifics, see the link below.
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