Multiple-depth mapping of soil properties using a visible and near infrared real-time soil sensor for a paddy field

In describing soil variability, information on the distribution of soil properties is required in both the horizontal and vertical directions. This study investigated the potential of a real-time soil sensor (RTSS) for mapping six soil properties at multiple soil depths of a paddy field. Soil spectra were acquired at three depths using RTSS. Three calibration models were developed. The first model (CM1) combined the dataset for depths of 10 and 15 cm, the second model (CM2) combined the dataset for depths of 15 and 20 cm, and the third model (CM3) combined all the three depths. CM3 was the best calibration model for all the soil properties. The generated maps exhibited variations in the distribution of all the soil properties at different depths.