Читать книгу Hydrogeology, Chemical Weathering, and Soil Formation - Allen Hunt - Страница 22

Roy W. Simonson’s (1959) generalized theory of soil genesis took a decidedly systems view of soils and elaborated upon Jenny’s view of the soil as an open system. He described four groups of physical, chemical, and biological processes common to all soils: additions of organic and mineral matter as solids, liquids, and gases; their removal; their transfer or translocation; and their transformation:

Simonson argued that the changing balances between these processes differentiate one soil from another. For example, mineralization and humification of plant litter engage more or less the same processes of transformation in all environments, but different process rates may lead to different end products.

Stanley Buol et al. (1980) categorized processes of soil formation using Simonson’s general scheme: enrichment, deposition on the soil surface, and littering are additions; leaching and surface erosion are removes; eluviation, lessivage, and pedoturbation are examples of transfers; and humification, mineralization, and weathering involve transformations. In Figure 1.1, Simonson’s model would engage the internal soil processes and forms with energy and material inputs from, and outputs to, the atmosphere, hydrosphere, biosphere, and anthroposphere. For the soil system to persist, incoming material must at least replace outgoing material. This fact was recognized by Constantin C. Nikiforoff (1959), who likened the situation to a section of an aggraded stream between two bends: water enters from upstream, water leaves downstream, but between the two bends nothing is lost and work is done. The corresponding “stream” in the soil system is the collection of surficial materials which constitute the soil. In the words of Buol et al. (1980, 11), “A soil is an evolving entity maintained in the midst of a stream of geologic, biologic, hydrologic, and meteorologic material.”