Soil Profile
The first step is to decide on (sub-) horizon boundaries. See video: Describing Soil Profile (also shown in the former section)
You also notice that a little soil sample from each (sub-) horizon is collected and put on the ground surface at the side of the pit. These samples (properly put in raw, from topsoil down to the bottom of the pit) are examined for color, pH (EC, if needed), texture, and ‘'consistency when wet''. The person in the pit continues with examining structure, consistency (when dry and when moist), porosity, percentage of course fragments, root distribution, etc.
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- Soil profile description is explained in Soil Survey Manual (USDA, 1993, Chapter 3), but the pocket size guidelines we normally have with us in the field is the one from Soil Profile Description (FAO Guidelines) (Online).
- ISRIC - World Soil Information Database (Online)
In summary: The pit is first carefully studied for its different horizons and layers (H, A, E, B, C, R) and then described horizon by horizon, for color, texture, structure, etc.
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The description card is filled out and kept in a file for later processing, see examples of
- Soil Description Cards (These are examples, as there is not an standardized format)
From the long list of soil characteristics which should be described texture and structure are very important (considering the objective of this course), and normally used to infer a number of other properties, such as bulk density, consistence, etc:
See the long list of soil characteristics (see also under ‘Table of Contents’ – Chapter 3-- in the beginning of the USDA Soil Survey Manual)
© International Institute for Geo-Information Science and Earth Observation (ITC), 2010