Measuring and Modeling Root Water Uptake in Soil

Water movement through the root zone has attracted an increasing interest during the last few decades. In this research, the spatial and temporal patterns of root water uptake were studied in the root zone of an apple tree. An important part of the root water uptake model is root length density which was measured by sampling soil cores in the one quarter of the root zone. A 2D model of root water uptake was established, which included root density distribution function, potential transpiration and soil water stress-modified factor. Root water uptake distribution was measured by an array of TDR probes and the model parameters were optimized, by minimizing the residuals between the measured and simulated data. Studies showed that the maximum root water uptake occurred at depth 10-30 cm. The results also showed an excellent agreement between the measured data and the simulated outputs, indicating that the developed root water uptake model was efficient and feasible.