Determination of some soil properties on consistency limits and penetration resistance and investigation the changing of this properties along with depth

The aim of this study was to determine the direct and indirect effects of soil properties affecting the liquid limit, plastic limit, plasticity index, and penetration resistance and to reveal the change of all investigated properties along the sample layers. In the 5 da pasture selected as the study area, 20 sampling points were determined randomly, penetration resistance values were read these points, then the soil samples were taken from 0-25cm (K1), 25-50cm (K2), and 50-75cm (K3) depths. The analyzes were carried out to determine the plastic limit, liquid limit, plasticity index, moisture content, grain size distribution, organic matter content, aggregation rate, aggregate stability and clay activity index. One-way variance analysis (ANOVA) was used to determine the differences between the layers in terms of the studied properties, and path analysis was used to determine the direct-indirect effects of the properties affecting the penetration resistance, liquid limit, plastic limit, and plasticity index. The clay content and penetration resistance increased, but sand, silt, moisture and organic matter content, aggregation rate, aggregate stability, clay activity index, liquid limit, and plastic limit decreased along the soil depth. It was determined that these differences observed throughout sampling layers were significant statically. As a result of path analysis, it was determined that the property with the highest direct effect coefficient on penetration resistance and liquid limit is clay content, on plastic limit is organic matter content. The relationships between consistency limits and penetration resistance was not occured at the expected level due to the fact that measurements could not be performed under different humidity conditions. In addition, it is concluded that some properties such as bulk density and void ratio should be included in the models in order to determine the properties that affect the compaction and consistency limits of soils more accurately. Keywords: Liquid limit, plastic limit, plasticity index, compaction, pasture