Distributed soil displacement and pressure associated with surface loading

Soil compaction is an inevitable result of agricultural practices. It alters physical properties of soil and tends to be undesirable as it adversely affects water and nutrient penetration. Furthermore, additional energy is spent to till the soil. Although a tremendous amount of research has been conducted in the area of soil compaction, the focus has been primarily on surface soil displacement. Realizing that the observed soil displacement is the cumulative effect from the compaction of subsurface layers, this research discusses the displacement and distributed pressure through the soil from a surface load. A given volume of soil of known density and moisture content was loaded at the surface with a slowly applied force using an Instron® testing machine. The distribution of the pressure and displacement profile from the surface to depth was measured to provide insight into the formation of the subsurface soil structures. The nonlinear exponential decay of the soil displacement (compaction) from the surface to a given depth converges to zero at the location of a hard, compact layer or a point where no soil movement occurs, regardless of the initial soil compaction. By increasing soil moisture content and decreasing soil bulk density, the vertical soil displacement increased at the surface and within the soil profile, and the pressure distribution decreased with depth. Changing the shape of loading surface had minimal effect on soil displacement