Improving Soil Texture Digital Mapping Using Landsat ۸ Satellite Imageries in Calcareous Soils of Southern Iran

Over the last three decades, there has been a general tendency for changing research methods on soil resource management from conventional and mainly qualitative methods to quantitative ones based on spatial correlation models, which are called Digital Soil Mapping (DSM). The present study was carried out in Shabankareh Plain (۱۵,۰۰۰ ha) with different physiographic units, in Bushehr Province, southern Iran. The target sites (۱۷۲ points) were selected for soil sampling at depths of ۰-۳۰ cm. Soil texture classes DSM was produced by two methods. The first method was Conventional DSM, in which data of soil particles was obtained from laboratory analysis for each sampling point along with their geographical location. Also, the study area boundary was added to ArcGIS software in UTM format and was analyzed by operating Kriging or IDW estimators. The map produced by this method was a low quality digital map containing extra and scattered texture classes with unrealistically sharp boundaries. The second method used CoKriging of L۸ multispectral imagery data (OLI bands) and soil samples analysis was operated. Results showed that using B۱ band (۰.۴۳۳-۰.۴۵۳ µm) of Landsat ۸ satellite imageries of the study area in April ۲۰۲۰ produced high quality digital maps. In this method, soil textures were the same as the ones in the study area. Salt accumulation and water content of surface soil were possible reasons indicating why satellite imageries in the other periods of year were not suitable for DSM. The highest and the lowest ranges of influence among soil texture parameters were ۶۸۴ meters and ۳۸۸ meter for clay and sand particles, respectively.

کلیدواژه ها:

CoKrigging ، Geostatistical methods ، Reflectance B۱band ، Soil particle zoning.