Soil and Land Evaluation: History, Definitions and Concepts

Land and soil evaluation is a classification system that assesses the best use for a given portion of territory, while evidencing the existing limitations for more or less specific types of use. Although land evaluation dates back to the introduction of agricultural use of land, it has only been since the beginning of the 20th century that, with the spread of pedology, and soil mapping, as a science in its own right, soil and land evaluation has taken on a purely territorial perspective. The term "land" is defined by the United Nations Food and Agriculture Organisation (FAO, 1985) as "an area of the earth's surface, the characteristics of which embrace all reasonably stable, or predictably cyclic, attributes of the biosphere ... including those of the atmosphere, the soil and underlying geology, the hydrology, the plant and animal populations, and the results of past and present human activity...." However, the objective of the evaluation may also be the soil itself, or rather the "soil type", meaning a group of soils with similar features and properties; so it is that we talk about soil evaluation. According to the Soil Taxonomy definition (1999), soil is a natural body, present on the land surface, formed by solid materials (minerals and organic matter), liquids and gases. Soil occupies space and is characterized by one or both of the following elements: (1) horizons or layers, which can be distinguished from the initial material as the consequence of additions, losses, transfers and transformations of energy and matter and (2) the capacity to support plants with root systems in a natural environment. The upper limit of soil borders the air, shallow water, live plants or undecayed plant matter.