In order to assess the influence of litter cover on soil background spectral response, trays of dry Lehmann Lovegrass (Eragrostis lehmanniana) were used at three different densities (635, 1015, 2815 Kg/ha) over three different soil backgrounds (Whitehouse sandy clay loam, Superstition sand, and Cloversprings loam). After analysis, spectral measurements made with a Barnes Multi-Modular Radiometer revealed that, soil-litter mixtures exhibit an oil like spectral behavior in the (0.45-2.30 m) waveband range. Mulched soils could not be discriminated from bare soils solely on the basis of the spectral response. However, mulched and bare soil spectral responses differed in amplitude depending on the difference in brightness between the bare soil and the litter cover. In addition, the results showed that while an increase of litter cover density on the soil surface decreased RVI, NDVI and PVI predicted greenness, it increased the GVI based greenness for all soils except the Superstition sand where the GVI showed a reversed trend. The PVI increased at low and intermediate litter densities and decreased at higher ones for the Superstition sand.

Thesis (M.S.)--Mississippi State University. Department of Agricultural and Biological Engineering. / Title from title screen. Includes bibliographical references.

An experiment was conducted to determine whether the water depth (above soil) and soil type would have any influence on the multispectral reflectances of paddy rice, and their calculated vegetation index values. The results showed that, when vegetation cover was low (below 600 grams of dry biomass per square meter), the near infrared (NIR) reflectances decreased very little with water depth. The same was true for red reflectances, but to a lesser degree. Overall the changes were not significant at 0.05 level of significance when the water depth was increased from 2.5 centimeters to 10 centimeters. When the vegetation cover became higher most NIR and red reflectances did not show a significant decrease with the increase of the water depth, and sometimes they even increased slightly up to a water depth of 6.4 cm. Nevertheless both rice cover and water depth as well as soils played an important role in the reflectance pattern in red and NIR bands. Some index values increased and some decreased depending on water depth and rice cover. Statistical analysis of the data showed that rice multispectral responses were mainly controlled by vegetation and minimally influenced by soil and water depths.

Everglades National Park is a hydro-ecologically significant wetland experiencing salinity ingress over the years. This motivated our study to map water salinity using a spatially weighted optimization model (SWOM); and soil salinity using land cover classes and EC thresholds. SWOM was calibrated and validated at 3-km grids with actual salinity for 1998–2001, and yielded acceptable R2 (0.89-0.92) and RMSE (1.73-1.92 ppt). Afterwards, seasonal water salinity mapping for 1996–97, 2004–05, and 2016 was carried out. For soil salinity mapping, supervised land cover classification was firstly carried out for 1996, 2000, 2006, 2010 and 2015; with the first four providing average accuracies of 82%-94% against existing NLCD classifications. The land cover classes and EC thresholds helped mapping four soil salinity classes namely, the non saline (EC = 0~2 dS/m), low saline (EC = 2~4 dS/m), moderate saline (EC = 4~8 dS/m) and high saline (EC >8 dS/m) areas. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection