During the winter, soils go through "freeze/thaw" cycles as temperatures change. There has been a fair amount of research on this subject; in general I believe the more freezing and thawing that occurs, the better. Soils contact and expand during this cycle and it serves as natures own aerification process because soils are moved. When moisture in the soil freezes, the soils increase in volume as water turns to ice and thus, air (pore) space is increased. This can also be referred to as "frost heaving" as the soils heaves upward. On roadways and hard surfaces, this can be a problem, but on golf courses, it is generally a good thing.
3 weeks ago