Search

This paper presents a multi-sensor remote sensing study of physically crusted soil with various moisture contents by using millimetre-wave backscatter radiation. The backscattered radiation was used to generate an empirical model to estimate soil moisture at the thin surface crust scale by using a set of soils with known moisture content as a reference. The model was then used to assess the moisture content of a new set of soils from the same group. Real-time measurement of soil moisture in the top layer beneath the soil crust is impractical at best and impossible using traditional methods. The proposed method, therefore, paves the way to assessing soil moisture content immediately beneath the surface crust as well as in a micro-profile at depths of 0-3 cm. It can be combined with other active and passive remote sensing methods to provide a micro-profile measurement of soil moisture to the depth of the entire upper root zone (0-30 cm) and of the plough layer (0-20 cm) under undisturbed conditions. The method is based on the emerging technology of millimetre waves, which provide improved spatial resolution of the subsurface concurrent with surface mapping. Further development and use of the method described herein will make it simple and practical to analyse and understand the processes governing the soil-water interface. The major processes for which this information is important are soil crusting, water budgets (infiltration, runoff and evaporation) and soil erosion. [ABSTRACT FROM AUTHOR]

Studies the feasibility of accounting for the crust status solely from the spectral information through the determination of the spectral signature of soil's structural crust in the 1.2 to 2.5 micrometer spectral region. Cumulative rainstorm energy and infiltration rate used; Ratio between sole and crust and built and crust spectra.

In this study, a controlled spectral investigation of the properties of structural crust, using infiltration rate as an indicator, was carried out, on a grumusol (typic chromoxerets) soil. The scope of this paper is to investigate the spectral relationship between structural crust and the infiltration rate and some related properties of a grumusol soil. Structural crust is a thin compact layer generated on the soil's surface after rainstorm events due to raindrop energy. The crust, which is a result of physical segregation and rearrangement of soil particles, affects some of the soil's physical properties, such as infiltration, run-off and soil erosion. A set of soil samples was subjected in the laboratory to increased levels of cumulative energy from a simulated rainstorm, while measuring the infiltration rate. The result was a set of soil samples with increased levels of crusting and correspondingly reduced infiltration rates. After drying the soil samples, their spectral parameters across the SWIR region (1.2 μm-2.4 μm) were studied in the laboratory. Empirical relations were found between the infiltration rate and reflectance values (either in raw or in first derivative domains). A spectral ratio manipulation, using a fog type rain treatment (characterized as having no rain energy) as reference, confirmed that, within the spectrum, changes in both albedo and absorption enabled the crust to be detected using reflectance radiation. This is basically because fine (mostly clay) mineral enrichment processes occurred at the surface of the crusted soil. These minerals (montmorillonite, calcite) are spectrally active across the selected spectral region. Although further study is required to fully account for other soils, rainstorm energies and water qualities, this technique suggests great potential as a tool for rapid, non-destructive, in situ assessment of crusted soil properties. [ABSTRACT FROM AUTHOR]