Soil Science
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[edit] Soil Science
Soil Science encompasses many aspects of soils study such as the disciplines of soil physics, soil chemistry, soil classification, soil microbiology, etc. One of these studies is pedology. Pedology is the study of soils in a three dimensional context in their natural setting across the landscape in terms of origins, morphology (forms), classifications, characteristics or attributes, profile or cross-section, surface and internal water relations, geology, plant ecology, etc. and interpretations for use and management.
Most soils develop from weathered mineral geologic materials and usually include some organic materials in their upper part. This is called the O horizon, and it is composed of organic material, generally not considered topsoil, but leaf litter and muck. The rock that the mineral part of the soil originates from is called the parent material. Through the further influence of the soil-forming processes of additions, removals, transfers and transformations the nature of the parent materials are altered to the extent that they become soils. The soil-forming processes are controlled by the soil forming factors of parent material, climate, living organisms, relief, and time. Thus the similarity or contrast of soils from place to place reflects the similarity or contrasts of the soil-forming processes and factors.
The primary convention for naming soils is to select a named geographic feature in the vicinity where the soil was first recognized and identified as a new soil, e.g: the Dunkirk soil series for the village of Dunkirk near Lake Erie, NY. All soils found to have closely similar attributes are classified as Dunkirk wherever they are found. That distribution can be more localized or it can be somewhat more extensive.
The description of the soil usually identifies attributes such as pH (degree of alkalinity or acidity), maturity (stage of pedogenic development), texture, consistence, color, gravel content and type, drainage class, and other soil features.
The United States and other nations have soil maps that show the soils in relation to one another as they occur across the landscape. On these maps each soil is characteristicaly related to a unique landscape position. Thus, the pattern of distribution and the location and extent of the soil type can be comprehended. Soil maps are a prime requisite for many users who need site information to make informed decisions on many aspects of use and management. Comparison of soil resources and their respective suitabilities and/or limitations can also be used to evaluate alternate sites for intended uses.
In the United States the Cooperative Soil Survey has more than a hundred year history. The various surveys were published with text and maps as soft covered books. Now they are published through the internet Web Soil Survey at: http://websoilsurvey.nrcs.usda.gov/app/
[edit] Soil Equations
The Bulk Density of a soil is it's dry mass divided by the total original volume of the soil. The porosity of a soil is the volume of it's pores divided by the total volume of the soil. The particle density of a soil is the mass of it's solids divided by the volume of it's solids.
