Abstract
The characteristics of Japanese soil were developed by wide paddy field farming, the influence of volcanic ash on soil, and a perudic moisture regime under temperate climatic conditions. Major soil classifications in Japan have developed in line with public work projects and soils in Japan have tended to be classified independently depending on the land use, such as cultivated area, forest, and so forth. Consequently, there is no available soil map drawn with a single framework of soil classification on a practical map scale, which hampers the progress of environmental studies such as watershed-level nutrient cycling, carbon sequestration and so on. In response, we published the Comprehensive Soil Classification System of Japan – First Approximation; a more practical system that enables the nationwide classification of soils. In it, we defined the following categories: soil great group, soil group, soil subgroup, and soil series group, determined by dichotomous keys. The proposed system contains 27 soil groups, 116 soil subgroups and 381 soil series groups. Setting these 4 category levels renders the system usable for both general outlines and detailed descriptions, and to create soil maps and soil information on various scales.
