Changes of topsoil bulk density and saturated hydraulic conductivity under infiltration condition of water storage pit

The bulk density and saturated hydraulic conductivity of topsoil are important physical parameters in studying water infiltration and soil water movement. Soil sections and digital images analysis techniques were used to study the effects of different infiltration heads on bulk density of the topsoil in sandy loam under water storage pit irrigation condition. The effects of different infiltration heads and soil bulk density on saturated hydraulic conductivity were tested. The comparative analysis between tested and computer simulated results of horizontal wetting front was conducted. The results indicated that infiltration head had a remarkable influence on the bulk density and saturated hydraulic conductivity of topsoil in sandy loam (soil bulk density was 1.345 g/cm3). With the increasing of infiltration head, the topsoil bulk density increased, soil became compact, and the saturated hydraulic conductivity of topsoil decreased. The power function could be used to describe the relationship between topsoil saturated hydraulic conductivity and infiltration head and soil bulk density. With the increasing of soil bulk density, the effect of infiltration head on saturated hydraulic conductivity decreased. When soil bulk density up to 1.466 g/cm3, infiltration head had few influence on saturated hydraulic conductivity. The results explore the micromechanism of the effect of infiltration head on the infiltration characteristics, and provide theoretical foundation for the further research in water storage pit irrigation.