Simulation of Root Zone Soil Moisture Dynamics and Optimization of Irrigation Scheduling for Greenhouse Strawberries Based on HYDRUS-3D

Understanding the dynamics of root zone soil water content is crucial for precision irrigation scheduling in protected strawberry cultivation. The HYDRUS-3D model is capable of simulating three-dimensional water flow and root water uptake. Although the model has been tested in various settings, its validation under realistic greenhouse cultivation rack systems with direct soil moisture measurements remains limited. In this study, a HYDRUS-3D model was developed to simulate root zone soil water dynamics in a greenhouse U-shaped strawberry cultivation system under both irrigated and non-irrigated conditions, with and without plastic mulch. In the first year, the model’s accuracy was evaluated using a newly developed line-scale dielectric soil moisture sensor. The simulated volumetric soil water content showed good agreement with sensor measurements across all scenarios (R2 ≥ 0.8302, RMSE ≤ 0.0309, NSE ≥ 0.5979). In the following two years, we utilized the established model to schedule irrigation and investigated its water-saving effects. Model-scheduled irrigation reduced water use by 8.45–13.36% compared with conventional irrigation scheduling. No significant differences were observed in most morphological, physiological, fruit quality, or yield indicators (p > 0.05). However, occasional improvements were detected in chlorophyll content, root activity, ascorbic acid and total soluble solids. These findings demonstrate that HYDRUS-3D effectively simulates root zone water content dynamics throughout the strawberry growth cycle and serves as a practical tool for precision soil water management in greenhouse cultivation rack systems.