Towards Green Initiatives: Advancing Root Zone Monitoring Using Non-Invasive Geophysical Techniques

Aligned with Saudi Arabia’s Vision 2030 Green Initiative, this study presents an innovative approach to sustainable agriculture in hyper-arid regions by integrating advanced geophysical methods to monitor tree root water uptake (RWU). The research highlights the combined use of modeling through HYDRUS-1D and Electrical Resistivity Imaging (ERI) for non-invasive root zone monitoring under controlled experimental conditions. The findings address critical challenges in agricultural water management in arid environments, where extreme temperatures and sandy soils significantly impact water dynamics and crop sustainability. RWU patterns of a citrus tree were simulated using HYDRUS-1D under varying soil and climatic conditions. The results revealed that the highest RWU rates occurred in the upper 30 cm of soil, predominantly during the morning. As temperatures increased, RWU activity shifted more profoundly into the soil profile. These insights are crucial for optimizing precision irrigation strategies in water-scarce regions. The model calibration utilized real-time soil moisture data collected through innovative 3D and 4D ERI methods—a seven-month experiment conducted in a controlled outdoor environment in Dhahran, Saudi Arabia. The experimental setup included a 2m x 2m x 2m wooden tank filled with sandy soil, in which a lemon tree was planted and monitored using ERI techniques. The 3D and 4D geoelectrical models captured temporal and spatial variations in root zone moisture content during irrigation events, providing unprecedented insights into subsurface water distribution and root activity dynamics.

A key outcome of the research was the successful detection of root activity through resistivity anomalies, confirming the potential of ERI as a non-invasive tool for root zone monitoring. This novel approach to root zone monitoring offers significant advantages over traditional methods. Unlike invasive techniques, such as soil coring, ERI provides high-resolution data without disrupting the natural state of the root system. Additionally, the continuous monitoring capability of ERI enables dynamic observation of root water uptake patterns over time, supporting the development of more efficient irrigation and water management practices. Integrating geophysical methods with numerical modeling presents a scalable and sustainable solution for addressing water management challenges in agriculture. This research improves water use efficiency, reduces environmental impact, and enhances crop productivity in hyper-arid regions by providing actionable insights into root zone moisture dynamics. The findings have broad applications in precision agriculture and environmental management. They underscore the importance of adopting innovative, non-invasive technologies to optimize resource utilization and achieve sustainable development goals in water-scarce regions.