Influence of Geometric Standard Deviation of Soil Particles (?g) over Spectral Reflectance of Soil Surface (Case study: Pol-e-Dokhtar, the Lorestan Province)



Homogeneity and uniformity of soil particles is a most potent factor which affects soil spectral signatures. Geometric standard deviation of soil particles (?g) exhibits the homogeneity of soil components. This study presents the influence of ?g on spectral studying of soil geometric mean particle diameter as well as lime. The study was conducted in Pol-e-Dokhtar using the data set of LISSIII-P6 , September 7th 2007. Subsequent to satellite data preprocessing, some such processes as: Normalized Difference Vegetation Index, Principal Component Analysis, Soil Line Euclidean Distance and Unsupervised Classification were carried out on the acquired data. By stratified randomized sampling method and according to the false color composite as well as photomorphic units of the main image of the study area, 95 sample points were eventually selected and samples collected from 0-5cm of soil surface. Geometric standard deviation (?g), geometric mean particle diameter (dg) and lime (CaCO3) were later determined for each soil sample in the lab. Samples were accordingly divided into two parts on the basis of the computed geometric standard deviation: the first, ?g <10 (homogeneous soil samples) and the second, ?g ?10 (heterogeneous soil samples). Subsequently via correlation operations in SPSS for both groups, it was expressly displayed that for the first group (?g <10), dg and lime were very forcefully and explicitly correlated with the remotely sensed data, in comparison with the second group (?g ?10). Hence, the geometric standard deviation of soil particles (?g) in the study region can powerfully impress soil spectral reflectance.