Soil Freezing Dynamics in a Changing Climate: Implications for Agriculture

Abstract

Soil freezing can affect winter cereals and perennial crops directly over winter, and it can affect all crops indirectly by modifying soil physical structure, soil moisture, microbial communities, and weed growth over the following growing season. Although climate warming is expected to increase mean air temperatures over winter, changes in snow cover and extreme temperature events could complicate the responses of soil freezing dynamics to climate change. I examined projections of soil freezing responses to climate change obtained using a variety of modeling, observational, and hindcasting approaches. Overall, despite a general pattern of a decreased numbers of days of frozen soil and decreased numbers of days with snow on the ground, projected responses of soil freezing dynamics to climate change have been regional in nature. Specifically, although southern temperate regions that currently experience mild winters will likely cease to experience soil freezing in some years, many northern temperate regions may experience an increased number of soil freeze-thaw cycles (FTC) as a result of reduced snow cover. Nevertheless, from the standpoint of agricultural impacts of soil freezing, an increased number of soil FTC may be of little consequence if it is not also accompanied by changes in the timing, severity or depth of soil freezing. The latter factors may be influenced strongly by changes in the timing of precipitation, which affects snow cover. The increased occurrence of extreme warming events may also affect the timing and strength of plant cold acclimation and deacclimation responses. The management of snow and plant litter cover may play an important role in modulating interactions between climate change and soil freezing responses in some systems.