Freezing Induced Field Soil Water Changes During Five Winters in West Central Minnesota

ABSTRACT SOIL freezing induced movement of soil water in the top 1.5 m of a Barnes loam soil (fme-loamy, mixed, Udic Haploboroll) was studied over the winters of 1982 to 83 through 1986 to 87 under fall plow, fall chisel, and no till systems each with and without residue. Measurements consisted of frost depth, snow depth, soil water content, air temperature, snowfall, and precipitation. Changes in soil water were determined relative to soil water content just before freezing. Changes in water content were related to depth of soil freezing and initial fall soil water content. Frost penetration was inversely related to snow depth. However, early season snowfall has a greater effect than later snowfall. Fall plowing traps the least snow and has the deepest frost. No till-residue plots trap the most snow and have the least frost. Uniform frost penetration was measured over all treatments in a year with virtually no snowfall. Initially dry soil grained water. Initially wet soil lost water. Greatest accumulation of water was measured 14 days before complete thawing, which is after maximum frost penetration when surface melting had started. In both wet and dry years water accumulated in frozen soil zones. Accumulation roughly coincided with arrival of the freezin front. Accumulation below the frozen zone occurred at the beginning of spring thaw or during mid-or late winter periods of snowmelt. Apparently water from snowmelt or surface soil thaw passed through frozen soil to unfrozen soil beneath.