Repeated Freeze-Thaw Cycle Effects on Soil Compaction in a Clay Loam in Northeastern Montana

In recent years, there has been an increased global concern regarding the impact of soil compaction on crop production and soil quality in modern mechanized agricultural farming systems. Farm equipment is heavier than ever before, and many farmers have resorted to energy intensive deep tillage to alleviate compaction. Freeze-thaw processes influence the physical properties of soil, primarily soil compaction and structure. A 3-yr field study was established in fall 2009 to investigate the effects of the dynamics of freeze-thaw cycles (FTCs) on soil compaction in a clay loam. Results showed that frequent FTCs over the winter generally alleviated soil compaction at the 0- to 30-cm depth. During the winter of 2009-2010, soil penetration resistance (PR) in compacted treatments that were subject to freezing and thawing conditions was significantly reduced by 73, 68, and 59% at depths of 0 to 10, 10 to 20, and 20 to 30 cm, respectively. In compacted soils that were not subject to freezing, PR was significantly reduced by approximately 50, 60, and 46% at the same respective depths of the soil profile presumably due to the biology of soil and disruptive effects of shrink-swell cycles caused by frequent wetting-drying processes. These results demonstrate that repeated FTCs can alleviate soil compaction and alter soil physical quality. We conclude that FTCs associated with typical winter weather conditions are the most effective and economical way to alleviate soil compaction and improve soil structure through the dynamics of FTCs.