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Classing the Soil Skeleton (Greater than Two Millimeters): Proposed Approach and Procedure
Author(s) -
Corti G.,
Ugolini F. C.,
Agnelli A.
Publication year - 1998
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1998.03615995006200060020x
Subject(s) - weathering , clastic rock , mineralogy , skeleton (computer programming) , soil water , geology , porosity , homogeneous , chemistry , soil science , geochemistry , sedimentary rock , mathematics , geotechnical engineering , combinatorics , computer science , programming language
In soil science, analytical procedures apply almost exclusively to the fine earth (<2 mm). Rock fragments or skeleton (>2 mm) are regarded as inert and discarded during sieving; however, we have found that the clasts display physical and chemical properties that can equal or surpass those of the fine earth. These properties depend largely on the degree of alteration of the clasts. In light of these findings, we developed a method to separate the rock fragments into weathering classes. This method has been applied to five European skeleton‐rich soils derived from different parent materials. Color intensity, roughness and irregularities of the surfaces, cracks, and surface features of the exposed minerals were considered reliable criteria for the separation of the clasts. We noticed also that the degree of alteration of the clasts corresponds to size: as size decreased, weathering increased. Consequently, sieving could be used for separating the weathering classes. On the basis of these criteria, clasts were differentiated into highly, moderately, and slightly altered. There are statistically significant differences among the weathering classes in terms of bulk density, porosity, organic C, total N, and cation‐exchange capacity. There are no statistically significant differences in pH. The results confirm that the procedure separates relatively homogeneous and different classes of rock fragments. We also compared the characteristics of the soil skeleton to those of the fine earth and fresh rock. We concluded that not characterizing the skeleton of the soils may provide distorted information on the capability of these substrata.