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Monitoring Soil Moisture With Distributed Acoustic Sensing in the Agricultural Setting

Description: 

Distributed Acoustic Sensing (DAS) emerges as a non-intrusive and high-resolution method for monitoring crucial agricultural soil properties. The deployment of fiber optic cables in the soil ensures minimal disturbance to the soil environment, enabling the comprehensive monitoring of soil health parameters, including moisture, density (compaction), temperature, and organic content through high-resolution ambient seismic signals. Each of these properties involves dynamic processes from multiple perspectives, posing challenges for extraction from a single observation type. In this study, we conducted a two-day DAS observation spanning approximately 150 meters in a farmland setting with diverse agricultural treatments. Employing ambient noise interferometry, we derived seismic velocity variations in both space and time, revealing a notable correlation between relative seismic velocity and soil moisture. A spectral analysis confirmed that ambient noise power spectral density serves as reliable proxies of precipitation intensity for shallow farmland soil. In addition to DAS, we co-located a Distributed Temperature Sensing (DTS) observation system to record the high-resolution temperature of the near-surface soil, influenced by soil moisture and air temperature diffusion. By combining the precipitation and surface temperature data with independently measured soil temperature, we developed a model representing the physical system of rainfall elastic load, diffusion in the soil, and evaporation. Our findings indicate that rainfall leads to an abrupt increase in soil moisture and a sudden drop in seismic velocity, followed by gradual recovery during the downward diffusion process (drainage). Notably, the substantial rise in seismic velocity, up to 60% at some plots depending on the tilling treatment, is best explained by thermoelasticity. We explore how the degree of tilling affects drainage and soil temperature. DAS exhibits substantial potential for real-time precision agriculture monitoring, offering opportunities to enhance resource management, sustainability, and crop productivity in the face of a changing climate.

Session: Advancing Seismology with Distributed Fiber Optic Sensing - II

Type: Oral

Date: 5/3/2024

Presentation Time: 10:45 AM (local time)

Presenting Author: Qibin

Student Presenter: No

Invited Presentation: 

Authors