A study of the relationships between root growth and physical properties of soils

Abstract

Laboratory and field studies were made to evaluate the influence of multiple roots of plants on some of the physical properties of Willacy fine sandy loam and Harlingen clay soils. The relationship between plant growth and soil physical properties were also determined. Studies were made to evaluate relationships between soil moisture suction, bulk density, hydraulic conductivity and soil strength. A high inverse curvilinear relationship between soil moisture suction and soil strength at different bulk densities were observed for Willacy fine sandy loam. These results demonstrated the dependence of soil strength on soil moisture and soil strength for Harlingen clay was linear from 0-40 bar soil strength. This relationship was found to be nonlinear above 40 bar soil strength. Soil strength of Harlingen clay decreased with increasing soil moisture content. The relationship between soil strength and hydraulic conductivity for Willacy fine sandy loam was found to be nonlinear and was inversely related. This relationship between the two parameters may be useful in estimating hydraulic conductivity of certain soils from an estimate of soil strength. There was no defined relationship between soil strength and hydraulic conductivity of Harlingen clay. Plant population increased soil strength of Willacy fine sandy loam and Harlingen clay soils. In Harlingen clay soil strength decreased with increasing plant population. The trend for higher soil strength in close proximity of plants was observed. The varying effect of roots on soil strength of sandy and clay soil was explained to be due to forces developed by axial and radial root pressures, elastic plastic properties of clay and rate of drying of soils..