Fundamental Steps for Regional and Country Level Soil Surveys

Abstract

The spatial and temporal data and information are essential for decision and policy making within each governing system as well as in conservation and sustainable management programs through the execution of soil surveys. The soil survey data are used to establish national and regional level databases. A unique method of soil survey was executed to map some soil attributes in 300,000 ha of Zayandeh-rud Valley, Isfahan, Central Iran. To establish a powerful database, it is important that soil surveys address the environmental impacts. To do so, the following steps were considered: (1) fundamental factors and processes for landscape formation, (2) evolution pathways of geomorphic surfaces, and (3) mapping of pedologic properties and visualization of collected information. Execution of mentioned steps highlighted some historical facts in study area. It has observed that some geomorphic surfaces have developed before Pleistocene period; the Zayandeh-rud River had three different pathways in Quaternary period; the pedodiversity indices are directly related to soil evolution and time; and the soil evolution pathways in this valley does not follow the convergence pathway of the Jenny’s theory. Results also indicate that the digitally extracted continuous maps have the ability to accurately show the spatial distribution of pedologic properties.