Effects of Frost Action on Soil Aggregate Stability

Abstract

ABSTRACT Arainfall simulator study was conducted on three Minnesota soils to examine the effects of soil type, initial soil moisture content at the time of freezing, rate of freezing, number of freeze-thaw cycles, and energy of raindrop impact on soil aggregate stability. For all three soils, the effect of raindrop impact energy was more pronounced than the effect of freezing and thawing on the disruption of soil aggregates. The rate of freezing had little or no significant effect on aggregate stability. While freezing, in general, resulted in a breakdown of soil aggregates, there were certain optimum soil moisture levels at which aggregate disruption as a result of frost action was minimized or reversed. The effect of number of freeze-thaw cycles on aggregate stability of the three soils tested was not consistent. Regression equations that relate the mean weight diameter of soil aggregates to these factors are presented.