Effect of Sampling Frequency on Geospatial Field Mapping from Tractor Operational Data

Purpose: This study investigated the impact of sampling frequency on the spatial interpolation accuracy of tractor performance data and identified an optimal frequency range that balances data processing efficiency with spatial reliability. Methods: A 78 kW tractor equipped with sensors and a data acquisition system was tested in two experimental fields. Eight performance variables—engine torque (ET), engine speed (ES), engine power (EP), engine fuel rate (EFR), travel speed (TS), draft force (DF), traction power (TP), and axle power (AP)—were recorded at 100 Hz and subsequently downsampled to 50, 20, 10, 5, and 1 Hz. Spatial interpolation was performed using the Kriging method in ArcGIS Pro, and prediction accuracy was evaluated with the coefficient of determination, normalized root mean square error, and a composite performance index (CPI). Results: Most variables maintained stable spatial interpretation performance, recording R² values above 0.830 at sampling frequencies of 10 Hz or higher. ET gradually declined as the sampling frequency decreased, with a pronounced drop in performance observed below 10 Hz. Traction-related variables (DF, TP) were sensitive to downsampling, exhibiting substantial decreases in R² and notable increases in NRMSE at 5 Hz and lower. Conclusions: Frequencies of 10 Hz or higher ensured stable performance while balancing data efficiency, with 10–20 Hz identified as the optimal interval for efficient mapping. These findings highlight the critical role of sampling frequency in spatial analysis and provide practical guidelines for precision agriculture.