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This is a list of U.S. state soils.A state soil is a soil that has special significance to a particular state.Each state in the United States has selected a state soil, twenty of which have been legislatively established.
Map of the United States showing what percentage of the soil in a given area is classified as an Ultisol-type soil. The great majority of the land area classified in the highest category (75%-or-greater Ultisol) lies in the South and overlays with the Piedmont Plateau, which runs as a diagonal line through the South from southeast (in Alabama) to northwest (up into parts of Maryland).
Soils are the product of climate, organisms and topography, acting on parent (geologic) material over time. Thus the great diversity of geologic materials, geomorphic processes, climatic conditions, biotic assemblages and land surface ages in the United States is responsible for the presence of an enormous variety of mineral and organic soils.
Soil temperature depends on the ratio of the energy absorbed to that lost. [68] Soil has a mean annual temperature from -10 to 26 °C according to biomes. [69] Soil temperature regulates seed germination, [70] breaking of seed dormancy, [71] [72] plant and root growth [73] and the availability of nutrients. [74]
If the soil has more than 15% by weight retained on a #4 sieve (R #4 > 15%), there is a significant amount of gravel, and the suffix "with gravel" may be added to the group name, but the group symbol does not change. For example, SP-SM could refer to "poorly graded SAND with silt" or "poorly graded SAND with silt and gravel."
The activity of soil is the ratio of the plasticity index to the clay size fraction. If activity is less than 0.75, the soil is inactive. If activity exceeds 1.4, then the soil is termed active. If activity lies within the above values, then the soil will be moderately active. [10]
In soil science, soil gradation is a classification of a coarse-grained soil that ranks the soil based on the different particle sizes contained in the soil. [1] Soil gradation is an important aspect of soil mechanics and geotechnical engineering because it is an indicator of other engineering properties such as compressibility , shear strength ...
In geotechnical engineering, soil compaction is the process in which stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water (or other liquid) being displaced from between the soil grains, then consolidation , not compaction, has ...