A portable soil surface roughness instrument for automatic two-dimensional profile roughness measurement in the field

Soil surface roughness, characterized by the unevenness of the soil surface, is a critical parameter influencing radar backscatter coefficients and microwave emissivity, and is essential for applications in agriculture, soil science, climate modeling, and geology. Current roughness measurement methods, such as manual pin meters and photogrammetry, face limitations in field portability, automation, and cost efficiency. To overcome these challenges, this study introduces a novel, portable instrument utilizing automated two-dimensional rotary laser scanning to quantify surface roughness. The device's innovative design integrates a tripod-mounted laser scanner that generates 1 cm-resolution horizontal profiles by calculating surface heights from rotation angles and distances, eliminating manual intervention and enabling rapid field deployment. Compared to traditional contact methods or LiDAR systems, the instrument achieves comparable accuracy (R2 = 0.97 vs. pin meters) while offering significant advantages in portability (<5 kg total weight), automation (full-profile measurement in < 30 s), and affordability (estimated cost <$2,705). Field experiments validated its ability to compute roughness parameters (RMS height, correlation length) critical for microwave remote sensing and soil erosion modeling. By bridging the gap between laboratory-grade precision and field practicality, this instrument provides researchers and agronomists with a cost-effective tool to advance microwave remote sensing, precision agriculture, climate forecasting, and soil conservation efforts.