|
The Canadian system of soil classification is more closely related to the American system than any other. They differ in several ways. The Canadian system is designed to cover only Canadian soils. The Canadian system dispenses with a sub-order hierarchical level. Solonetzic and Gleysolic soils are differentiated at the order level. The American system is designed so that surface tillage cannot result in a change in classification. Canada's first independent taxonomic system of soil classification was introduced in 1955. Prior to 1955, systems of classification used in Canada were strongly based on methods being applied in the United States. However, the U.S. system was based on environmental conditions common to the United States. Canadian soil scientists required a new method of soil classification that focused on pedogenic processes in cool climatic environments. Like the US system, the Canadian System of Soil Classification differentiates soil types on the basis of measured properties of the profile and uses a hierarchical scheme to classify soils from general to specific. The most recent version of the classification system has five categories in its hierarchical structure. From general to specific, the major categories in this system are: ''orders'', ''great groups'', ''subgroups'', ''families'', and ''series''. At its most general level, the Canadian System recognizes ten different soil orders: Classification involves arranging individual units with similar characteristics into groups. Soils do not occur as discrete entities; thus the unit of measurement for soil is not obvious. This unit of measurement is called the pedon, defined as a 3-dimensional body, commonly with lateral dimensions of 1 m and depth of 1 to 2 m. A vertical section of a pedon displays the more-or-less horizontal layers (horizons) developed by the action of soil-forming processes. Soil classification facilitates the organization and communication of information about soils, as well as the understanding of relationships between soils and environmental factors. The land area of Canada (excluding inland waters) is approximately 9 180 000 km2, of which about 1 375 000 km2 (15%) is rock land. The remainder is classified according to the Canadian system of soil classification, which groups soils into sets of classes at 5 levels or categories from most general to most specific: order, great group, subgroup, family, series. There are 10 orders and several thousand series. Thus the system makes it possible to consider soils at different levels of specificity. Soil classes are defined as specifically as possible to permit uniformity of classification. Limits between classes are arbitrary as there are few sharp divisions of the soil continuum in nature. Differences in soils are the result of the interaction of many factors: climate, organisms, parent material, relief and time. The soil classification system changes as knowledge grows through soil mapping and research in Canada and elsewhere. ==Orders== 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Canadian system of soil classification」の詳細全文を読む スポンサード リンク
|