Although plant genetics and cutting management are most likely the primary factors affecting alfalfa persistence, proper fertility management can significantly improve winter survival in several ways. High fertility results in increased root branching and extension, increased growth rate after winter, increased stored food reserves, lowered cell freezing point, and increased disease resistance. Soil pH has been shown to be a significant factor in influencing stand persistence. Considerable research has been conducted that illustrates the importance of fertilization on stand survival under Wisconsin conditions. Specific studies that illustrate the substantial decrease in stand survival associated with more acid soils include Wang et al. (1953), Kelling et al. (1982), Peters and Kelling (1988), Kelling and Wolkowski (1991), and Kelling et al. (1998a). These data from several locations showed that stand survival was strongly linked to pH and that the pH necessary for optimum survival was at least 6.4, and often 6.7, or above.