Frost Heave of Alfalfa as Affected by Harvest Schedule

Abstract

AbstractFrost heave of alfalfa (Medicago sativa L.) occurs periodically in northern areas of the United States, and frequently results in serious stand losses. Studies were conducted at Wooster, OH, to determine the effect of date of initial harvest, harvest frequency, and date of final harvest on yield and persistence of alfalfa on a Wooster silt loam (fine‐loamy, mixed, mesic Typic Fragiudalf), a frost heave susceptible soil. Late‐autumn harvests (late October) were a major factor associated with frost heave in this research. An average of 38 and 28% frost heave occurred in 1986 and 1987, respectively, compared to 5 and 7% with no late‐autumn harvests for the same years. The extent of frost heave was not related to average root weight, percent of roots branched, or percent total nonstructural carbohydrates. The two winters had high soil moisture, soil temperatures slightly below freezing, and no snow cover for relatively long periods, factors previously recognized as related to frost heave. Soil cover provided by leaving the autumn regrowth appeared to be the major effect in reducing the amount of frost heave that occurred by modifying the soil temperature. The practice of late‐autumn harvesting has become widespread in recent years. Producers with soils subject to heaving must consider the value of leaving the regrowth as protection against frost heave damage and potential loss of the alfalfa stand, against the value of the harvested forage.