Abstract

Ground-penetrating radar (GPR) with a suspended 1-GHz horn antenna was deployed over bare and vegetated soil surfaces using surface reflection (SR) magnitudes and propagation times (PT) to calculate bulk soil dielectric permittivity and soil water contents. Concurrent radar measurements over sand, Millville silt loam (coarse-silty, carbonatic, mesic Typic Haploxerolls), and sand–bentonite surfaces showed rapid drainage from sand and slower drainage from higher-surface-area textured soils. Soil texture and temperature affected diurnal variations in measured water content (occurrence of minima and maxima) for both SR and 2-cm time-domain reflectometry (TDR) water content data. Measurements over wheat canopy showed that while SR values were strongly altered by canopy biomass, PT measurements remained unaffected. Wheat canopy influence on SR gradually intensified during the growth season until the canopy was removed and SR-based measurements rejoined with PT data. Hornantenna radar measurements over natural surfaces offer a promise for remote mapping of soil texture and truthing of radar data collected from air- and spaceborne platforms, and they may be used in the field for water content and vegetation biomass measurements.

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