SODS: Soil Health On-Demand Sensors-A Multi Parameter Field Study with Temporal Monitoring

Real-time monitoring of soil health parameters is crucial for efficient use of resources, improving agricultural productivity, and sustainability. Traditional soil analysis methods, although accurate, are time-consuming and lack the spatial and temporal resolution necessary for dynamic agricultural environments. Recent advancements in sensor technology offer promising alternatives, enabling real-time, in situ monitoring of key soil health indicators. This study details the deployment and validation of novel Sensor-in-Field probes at the Donald Danforth Plant Science Center Farm in Missouri, U.S., in a winter wheat plot. Three Sensor-in-Field probes were evaluated for their ability to measure nitrate (NO₃), ammonium (NH₄), soil organic matter (SOM), carbonaceous soil minerals (CSMs), soil volumetric density (SVD), soil hydration state (SHS), and total soil carbon (TSC) over a 28-day period. The probes' coefficients of variation were well within acceptable limits (<20%) for all parameters. The measured metrics averaged 0.05% ± 0.001 and 1.92% ± 0.02 for CSMs and SOM, respectively, while TSC was 1.18% ± 0.15. For the nutrients, the measured NO₃ and NH₄ values were 4.44 ppm ± 0.37 and 2.78 ppm ± 0.22, respectively. The accuracy of the soil probes was validated at a certified traditional soil analysis laboratory. Three samples were collected at three different time points and analyzed. Bland-Altman analysis showed <± 10% difference between the soil probes and traditional lab analysis for CSMs, SOM, and TSC, while t-test analysis reported p-values > 0.005 for NO₃, NH₄, and SHS/SVD, indicating non-significant differences between the probes and traditional soil analysis methods.