Quantifying the effect of soil physical properties on the compressive characteristics of two arable soils using uniaxial compression tests

The compaction of cultivated soils by agricultural machines considerably affects both the structure and physical properties of soil, and thus can have major impacts on crop production and the environment. In this study, we have used experimentally determined soil compression curves to constrain two important soil compression properties for black and brown soil from northeast China: the compression index and pre-compression stress condition. We have investigated the impact of variable initial water contents (0.14, 0.16, 0.18, 0.20 and 0.22 g/g) and initial bulk densities (1.20, 1.30, 1.45 and 1.60 Mg/m(3)) on these compressive properties by performing uniaxial compression tests on both types of remolded soils. It was determined that the pre-compression stress values were higher for black soil than for brown soil, whereas the opposite was true for the compression indexes, suggesting that black soil is less vulnerable to soil compaction than brown soil. The effect of initial water content, bulk density and the mutual interaction between them significantly influenced the compression properties of both soils (P < 0.01). The pre-compression stress condition of both arable soils showed a positive correlation with bulk density and a negative correlation with water content. By contrast, the compression index for both soils showed a prominent negative correlation with bulk density. The compression index of brown soil showed an insignificant dependence on water content, but showed a positive correlation for black soil. Consequently, cultivation operations should be avoided under low bulk densities and high water contents on the premise that the crops could grow well in order to reduce the risk of soil compaction. (C) 2014 Elsevier B.V. All rights reserved.