Manual and ground penetrating radar field measurements of field-corn spacing, planting depth, and furrow feature identification

The objective of this study was to investigate the utility of a 2.6 GHz GPR system to measure seed spacing and planting depth in a closed furrow and identify features that could potentially represent the furrow path. The experimental design had four treatments: two downforce pressures, three populations and planting depth, and two plots. The downforces significantly affected the planting depths and variability. The planting depth variability was more than the nominal resolution of the planter. The planter failed to satisfy the percent coefficient of precision and coefficient of planting depth accuracy parameters. Hyperbolic features were observed in the radargrams, but there were random across the radargram. The hyperbolic features were inconsistent with the seed depth and it was challenging to identify individual corn seed. There were horizontal features that were consistent and had similar two-way travel times to the bands observed in parallel and perpendicular radargrams. If the two-way travel times were the same, then it is highly likely that the bands in the parallel and perpendicular radargrams are from the same feature. Using the perpendicular to matchup with the parallel A-scans features that could represent the furrow were effectively identified.