Submitted to: American Geophysical Union
Publication Type: Abstract Only
Publication Acceptance Date: 12/12/1997
Publication Date: N/A
Technical Abstract: Overwinter freezing and thawing in agricultural fields changes the soil physical properties and affects the movement of water and solutes in the soil. These effects often carry over into the subsequent cropping season. It is necessary to understand these overwinter processes and effects to develop efficient and sustainable agricultural systems. Soil columns packed with a silty clay loam topsoil were buried vertically in a field near Ankeny, Iowa and extracted for sampling at regular intervals throughout the winter. Soil temperatures, soil water contents, solute concentrations, and frost depths were monitored in the soil columns and the surrounding field soil. Weather station data plus snow depth, snow density, and plant residue cover were used in the Soil-Heat-Atmosphere-Water (SHAW) model to predict frost depth and the movement of soil water and solutes. Data were collected for four winters starting in the fall of 1992. Soil water and solute movement were evident throughout the winter period and during the spring melt. Frost depths depended on snow cover, residue cover, and soil conditions. The SHAW model adequately predicted frost depths most of the time. Unexpected solute movement through preferential flow paths occurred in some cases and was not predicted by the model. This work has shown the need for soil freeze/thaw research and is continuing.