LAUSR

ABSTRACT Improved process understanding of temporal change in soil hydraulic, water retention, and soil physical properties is required to improve modelling of soil-water dynamics. This study reports on temporal trends in soil physical properties for intensive till and no till irrigated wheat, from autumn sowing to summer harvest. There were significant temporal trends for bulk density, readily available water capacity, and unsaturated hydraulic conductivity (at three matric potentials). Using a simple two-parameter exponential model for unsaturated hydraulic conductivity, the model coefficients appeared to increase over the first 10 weeks, followed by a decrease and later increase, but the temporal effect when using this model was not significant given the parameter uncertainty. Daily rainfall, irrigation, and evapotranspiration were evaluated as possible explanatory variables, but these were not generally significant in explaining temporal trends of soil properties. An implication is the need to provide temporal data to parameterise hydrological models for more accurate modelling, including irrigation scheduling.