| dc.description.abstract | The presence of coarse fragments (rocks) can impact soil physical properties such as volumetric water content, bulk density, and plant available water. Soils containing greater than 35 percent coarse fragments by volume are considered skeletal soils. Skeletal soils can be highly sensitive to erosion, occur in ecosystems of volatile carbon fluxes, and are difficult to restore once damaged. Furthermore, desertification in skeletal soils can directly impact local inhabitants through changes in property values, tourism resources, and local agricultural economies. Due to the sensitivity of the ecosystems in which skeletal soils are found, understanding their relationship with soil moisture is crucial for best land management efforts. Although a variety of sensors can measure soil moisture, many have measurement volumes that are too small or too large to give useful information at the landscape scale. The presence of coarse fragments further complicates soil moisture measurements by increasing the spatial variability of soil properties and acting as physical barriers for in situ sensors. The cosmic-ray soil moisture observation system (COSMOS) rover is a passive, non-invasive surface soil moisture sensor with a footprint greater than 100 m. However, the COSMOS rover has yet to be calibrated in a skeletal soil. Our objective was to calibrate the COSMOS rover in a skeletal soil to assess the impact coarse fragments have on surface soil moisture sensing. COSMOS rover surveys were conducted under three soil moisture conditions. Electrical conductivity surveys were conducted to estimate the spatial distribution of coarse fragments within the COSMOS footprint for each survey. Soil samples were taken to determine a ground measured bulk density, water content, and coarse fragment percent volume. The COSMOS measurements were then compared to the ground truth water content measurements by interpolating them over the COSMOS footprint. As expected, there was a decrease in water content as the percent volume of coarse fragment increased. COSMOS measurements responded to both changes in coarse fragment volume and changes in soil wetness with rainfall events. The COSMOS was able to accurately measure the soil water content of a skeletal soil without an additional correction factor for coarse fragment content. | en |
