Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 2, 2005
Publication Date: November 7, 2005
Citation: Benjamin, J.G. 2005. Freeze-thaw effects on penetrometer resistance and shear strength of two soils. Agronomy Abstract. Presented at the 2005 ASA, CSSA-SSSA International Annual Meeting. Nov. 6-10, 2005. Salt Lake City, UT Technical Abstract: High soil strength caused by soil compaction is of concern to farmers in most mechanized farming systems, particularly when no-till soil management is used. Farmers in temperate climates rely on winter freezing and thawing to partially alleviate soil compaction in these systems. The effectiveness of the freeze-thaw process for alleviating soil strength is little understood. A study was conducted to determine the effects of the number and duration of freeze-thaw cycles for decreasing soil strength. Loam soil and clay soil were compacted at three water contents with two impact energies using an automated soil compactor. The soils were periodically inserted and removed from a freezer over a 12 week period to apply freeze-thaw cycles. Penetrometer resistance was measured with a fall-cone device. Soil shear strength was measured with a motorized torsion shear device. The loam soil compacted to bulk densities in the 1.3 to 1.8 g cm-1 range while the clay compacted to bulk densities in the 0.9 to 1.4 g cm-1 range depending on water content and compaction energy. Bulk density did not noticeably change due to freeze-thaw cycles but shear strength and penetrometer resistance were decreased by greater numbers of cycles and longer freezing times. Soil strength decreased more in the clay soil compared with the loam soil. These results indicate that freeze-thaw cycles can reduce soil strength even if no bulk density changes occur.