Susceptibility to Compression of a Clay Loam Haplaquoll1
- J. L. B. Culley and
- W. E. Larson2
The objective of this study was to determine the compressibility of a poorly drained clay loam soil cropped to corn (Zea mays L.) with moldboard plowing as primary tillage (CN) or with no tillage (NT). Undisturbed cylindrical cores (100 cm3)obtained from planter-tracked (WT) and untracked (NWT) interrows just prior to harvest, were subjected to uniaxial compression after being equilibrated at soil moisture potentials (ψ) of −5, −10, −20, and −40 kPa. The precompression (over-consolidated) and virgin compression regions were isolated by plotting bulk weight volume (v) against the logarithm of applied pressure. The breakpoint or precompression pressures (σp), which separated the over- and virgin compression regions, were determined using a statistical procedure. There was no apparent σp for cores from CN-NWT interrows with ψ at or above −10 kPa. Tracking of tilled interrows resulted in the presence of over-consolidated regions at all moisture potentials. Virgin compression indices (slopes) decreased in the order CN-NWT > CN-WT > NT-NWT > NT-WT. A highly significant correlation (p < 0.01) was obtained between σp and the undrained strength as measured by the fall-cone device.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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