Alfalfa Persistence under Infrequent Cutting

Abstract

Alfalfa (Medicago sativa L.) cultivars have been developed for modern forage production systems with three or four cuts per year. Little is known about persistence of alfalfa cultivars in unharvested systems such as Conservation Reserve Program (CRP) fields. Our objective was to determine the stand persistence of alfalfa cultivars that were not harvested or harvested once per year. Twenty-three alfalfa cultivars representing a range of fall dormancy and disease resistance were established in binary mixture with timothy (Phleum pratense L.) at Becker, Grand Rapids, Morris, Rosemount, and Waseca, MN. Cutting treatments, which included a single cut per year (about 1 August) or no cutting were applied for 3 yr. Cutting treatment effects at Rosemount, Becker, Grand Rapids, and Waseca suggest that annual cutting of alfalfa-grass mixtures on CRP land would enhance alfalfa persistence, but stand survival of many cultivars was lower than that normally observed in cultivar trial plots cut three or four times per year. At Becker and Morris, fall dormancy was a good predictor of stand survival. There was no relationship between stand survival and disease resistance of cultivars. Annual mowing should be considered as a tool for maintaining alfalfa in CRP fields at some locations, but cultivars designed for the CRP program, which normally does not allow cutting, are needed.