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| Hauptseite > Publikationsdatenbank > Using crosshole GPR to monitore the impact of maize roots and nitrate fertilizer on the soil-plant continuum |
| Hauptseite > Publikationsdatenbank > Using crosshole GPR to monitore the impact of maize roots and nitrate fertilizer on the soil-plant continuum |
| Conference Presentation (After Call) | FZJ-2025-02084 |
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2025
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Please use a persistent id in citations: doi:10.34734/FZJ-2025-02084
Abstract: Non-invasive imaging of soil-plant parameters is crucial for precision agriculture, particularly for managing natural resources such as groundwater. This study demonstrates the potential of cross-hole ground-penetrating radar (GPR) to monitor soil water variations in the presence of maize crop roots using two different GPR frequencies, and the effect of varying nitrate fertilizer concentrations on GPR data. In 2023, weekly time-lapse GPR measurements were conducted during a maize growing season using 200 MHz and 500 MHz borehole systems at the upper minirhizotron facility in Selhausen, Germany. The facility features horizontal rhizotubes arranged in three columns, allowing for measurements at depths between 0.1 m and 1.2 m. GPR data are collected using horizontal zero-offset profiling (ZOP) at five depths between 0.2 m and 1.2 m, while root images are obtained at all six depths. Variations in soil water and root presence are primarily related to relative permittivity, while nitrate fertilizer concentrations are expected to affect soil conductivity and GPR signal attenuation. The GPR signal strength was analyzed by calculating the envelope of each trace and identifying maximum amplitudes to differentiate areas of varying conductivities and nitrate fertilizer concentration. In addition, the permittivity and maximum amplitudes are trend corrected to reduce the static and dynamic influence on the signals and to allow time-lapse comparison. Trend-corrected permittivity results shows increased variability over time up to depths of 0.6 m and 0.8 m, correlating with higher root presence, while maximum amplitudes shows greater variability only at 0.2 m. A statistical approach reveals a correlation with r2>0.5 between the standard deviation of the 200 MHz GPR data and root data for trend-corrected permittivities at 0.2 m and 0.8 m, but only at 0.2 m for maximum amplitudes. The 500 MHz data improves the resolution of small structures, when both data are compared along the tube but did not show the same correlation. Preliminary findings suggest that varying nitrate concentrations impact GPR data along rhizotubes, with both frequencies indicating decreased maximum amplitudes in areas with higher nitrate fertilization. These results highlight the potential of GPR as a non-invasive tool to accurately map root zones and to assess spatial variations in nitrate concentrations, enhancing precision farming practices and promoting sustainable crop management.
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