CONICET | Buscador de Institutos y Recursos Humanos

The available information for agricultural soils about the physical-mechanic behavior in response to the external loads that are applied during the activities of tillage and traffic is scarce in Argentina, and nonexistent in the Santa Fe State. Neither models have been generated that allow the estimation of this behavior. Mollisols of Santa Fe have silty-loam textures and moderate-low organic carbon contents. The general aim of this research was to determine the effect of intrinsic soil properties on the compaction susceptibility, preconsolidation pressure and compression curve of Mollisols, and to develop pedotransfer functions that allow the estimation of these parameters. The main productive soils of the Santa Fe State (i.e. Argiudolls and Hapludolls) were selected to carry out the study. Undisturbed soil samples (A horizon) were taken in 14 soil series that differ in texture (clay: 11-35%, silt: 20-75%, sand: 3-68%) and organic matter (2-4.5%). The uniaxial compression test was applied to the samples (n=70) previously exposed to five matric potentials (-6,-10, -30, -100 and -250 kPa) to generate a moisture gradient. After load withdrawal, soil bulk density (), particle density (p), void ratio (e), gravimetric soil moisture (Wg), particle size distribution, and organic matter (OM) were determined. The compression curves, the compression index (Cc) and the preconsolidation pressure (p) were obtained. A lineal relationship (R2=0.71) was determined between Cc and Wg,  and clay+silt content. There was an interaction between  and clay+silt content. Organic matter did not affect Cc. p was significantly related with Wg, clay content and OM (R2=0.76), but was unaffected by initial . Soil compressibility was dependent on the initial , clay content and Wg. A nonlinear model fitted the data with R2=0.84. The developed models could be very useful to estimate the soils compressibility using information of properties that are routinely evaluated.