Ground penetrating radar (GPR) detects fine roots of agricultural crops in the field

Ground penetrating radar (GPR) as a non-invasive technique is widely used in coarse root detection. However, the applicability of the technique to detect fine roots of agricultural crops is unknown. The objective of this study was to assess the feasibility of utilizing GPR to detect fine roots in the field. This study was conducted in four locations with different soil types and soil moisture conditions in Texas. Several varieties of winter wheat and energy cane were scanned with GPR (1600 MHz). Soil cores were collected immediately after scanning to measure root parameters. Using an image analysis software, four pixel indices with or without intensity threshold were used to assess the relationships between GPR signal and root parameters. There were significant relations between GPR indices and root parameters depending on soil conditions. The accuracy of root estimation was higher in wet clay soils than in dry sandy soils. Estimated root parameters from GPR had lower variation than measured roots. Average GPR pixel intensity without intensity threshold may be better to reflect root information than pixel indices with intensity threshold. This study demonstrates that GPR has the potential to predict bulk root biomass and diameter in winter wheat and energy cane.