PSXII-10 - Concordance Between a Time-of-flight Sensor and Plate Meter Method for Estimating Forage Mass

Abstract: This project explored the use of a time-of-flight sensor (ToF) as an alternative to the plate meter (PM) for estimating forage mass. The ToF configuration included a single beam TFmini Plus LiDAR Module (Benewake Co., Haidian District, Beijing, China), an Arduino Uno (manufactured by Arduino S.r.l., Torino, Italy), and either a PC or cellular phone for datalogging transmitted serial values sent over a USB connection. The ToF configuration was attached to a utility vehicle drawn sled with a ground to sensor distance of 84cm. A reflective mat was attached to the sled that floated atop the forage canopy to create a height area to compensate for the narrow field of view of the sensor beam (≤ 5cm). Six comparisons were conducted between the ToF and PM including warm-season and cool-season forage stands. Both the ToF and PM were calibrated by clipping 10, 14, or 20 calibration squares each to a 5cm residual forage height followed by drying clipped forage at 55C. Calibration coefficient of determination ranged from 0.86 to 0.95 and 0.86 to 0.96 for ToF and PM, respectively. Pearson’s correlation and Lin’s concordance coefficients ranged from 0.45 to 0.95 and 0.36 to 0.92, respectively. While both the ToF and PM demonstrated a predictable relationship between their respective height measurements and clipped area forage mass, the concordance between the two methods was weak for some comparisons, likely due to within field sample point variation between the two methods. Further research is needed to better understand mat density, sampling intensity, and plant density and height on the potential use of the ToF as an alternative to the PM.