Classification soils

The U.S. Department of Agriculture (USDA) soil classification system was developed for use in describing soils in which plants grow.63-66 The USDA system is now universally accepted within the United States and it should be used to describe soils used in ET landfill covers. 

Clay is the most important component of soil liners because the clay fraction of the soil ensures low hydraulic conductivity. In the United States, however, there is some ambiguity in defining the term clay because two soil classification systems are widely used. One system, published by the American Society for Testing and Materials (ASTM), is used predominantly by civil engineers.18 The other, the U.S. Department of Agriculture s (USDA s) soil classification system, is used primarily by soil scientists, agronomists, and soil physicists.19... 

ASTM and USDA Soil Classification by Grain Size... 

The distinction between various particle sizes differs between ASTM and USDA soil classification systems (see Table 26.2). In the ASTM system, for example, sand-sized particles are defined as those able to pass a No. 4 sieve but not able to pass a No. 200 sieve, fixing a grain size of between 0.075 and 4.74 mm. The USDA soil classification system specifies a grain size for sand between 0.050 and 2 mm. 

FIGURE 26.5 USDA soil classification. (Adapted from U.S. EPA, Requirements for Hazardous Waste Landfill Design, Construction, and Closure, EPA/625/4-89/022, U.S. Environmental Protection Agency, Cincinnati, OH, August 1989.)... 

Soil Survey Staff. Soil taxonomy, a basic system of soil classification for making and interpreting soil surveys. U.S. Dept. Agric. Handbook, 436. Washington D.C. Soil Conserv Serv, 1975. 

Many other designators are used for various horizons and horizon conditions. A complete list of these will not be given here but can be found in any introductory soils text or book on soil classification. 

Dent D, Anthony Y. Soil Survey and Land Evaluation. Boston Allen Unwin 1981. Douglas LA. Soil Micromorphology and Soil Classification, Thompson ML (ed.). 

Soil Survey Staff. Soil Taxonomy A Basic System of Soil Classification for Making and Interpreting Soil Surveys. Washington, DC U.S. Government Printing Office 1975. 

Most of the landforms in which wetlands form can be seen in tracing a river from its source in hilly or mountainous areas to its outflow in coastal floodplains and the sea. The main landforms are inland valleys, allnvial fans or fan complexes, meander or lacustrine floodplains, and allnvial terraces (Figure 1.4), and each of these is associated with particnlar soils as illnstrated for ricelands in Asia in Table 1.6. This section gives a brief description of these associations. More complete descriptions are given in Moormann and van Breemen (1978), Driessen and Moormann (1985) and Richardson and Vepraskas (2001). Following these anthors I use the USDA (1999) soil classification. 

USDA (1999) soil classification, na, not applicable —, absent or rare +, common ++, abundant. 

Surficial deposits at XY are dominated by tills and colluvium, which have been locally reworked by alluvial and glacio-fluvial processes (Figs. 1 2a). On the transect reported herein, the depth of overburden varies from negligible on mountain sides to at least 5 m thick in central parts of the till plain in central valley areas (unknown maximum thickness). In the section of the traverse the XY ore zone is c. 10 m thick, and occurs below c. 3 m of colluvial overburden (Fig. 2). Pedogenesis is generally restricted to minor to moderate horizonation that has produced predominantly brunisols (Canadian Soil Classification System, Agri-Canada 1998). 

Agri-Canada (1998). The Canadian System of Soil Classification. 3rd Edition. Ottawa, Agriculture and Agri-Food Canada. 

Sorbents Redox buffering > Aggregation Plant nutrient Pedogenesis Soil classifications... 

Quantifying soil morphology in tropical environments Methods and application in soil classification. Soil Sci. Soc. Am. J. 64 1423-1433... 

Soil classification has been oriented to soil properties in recent years, but still is tempered with concepts of soil genesis, with external associations, and with the use of the soil. The first systematic classification was by Dokuchaiev in Russia in 1882, Based upon field and laboratory characteristics, soils were grouped into three categories—normal soils of the dry-land vegetative zones and moors, transitional soils of washed or dry land sediments and abnormal soils. The system involved properties of the soil with external associations of climate and vegetation. Later, an associate (Sibirtsev) renamed the highest classes zonal intrazonal, and azonal. 

Note Further details can be obtained from Soil Classification, A Comprehensive System 7th Approximation/ Soil Conservation Service, U S. Department of Agriculture. Washington, DC. (Published periodically). 

In summary, this set of 264 nonfractionated whole soil samples, which could be grouped according to major soil units of the World Reference Base soil classification, is possibly the largest sample set that has been characterized by an extremely sensitive, versatile analytical method under identical experimental conditions. 

The sophistication and effectiveness of soil classification reflects the level of scientific maturity and an understanding of the particular area of study (Simonson 1959). A major aim of classification is to usefully summarize the natural variability of forms the entity takes and to enhance communication... 

Isbell, R. F. (1996). The Australian Soil Classification. Collingwood, Australia CSIRO Publishing. 

---