Effects of Biosolids Application on Temporal Variations in SoilPhysical and Unsaturated Hydraulic Properties

The objective of this study was to determine the effects of biosolids on temporal variability of physical and hydraulic properties of a calcareous soil. The biosolids was added to the soil at 0, 25, 50 and 100 Mg ha–1. Soil physical properties including aggregate stability, bulk density, saturated hydraulic conductivity, final infiltration rate and available water capacity were determined at 28, 85, 145, 221, 441 and 530 days after the biosolids application. The soil physical properties significantly changed in different sampling dates showing a significant temporal variation following the biosolids application. The unsaturated hydraulic properties were estimated using van Genuchten (1980) and Mualem (1976) equations. Unsaturated hydraulic properties significantly change following biosolids application and sampling dates. The soil moisture characteristic and unsaturated hydraulic conductivity are key parameters in water flow and solute transport modeling processes. Thus, the temporal variations in soil physical and hydraulic properties should be considered in solute transport modeling and studies following biosolids application.