ALLOCATIONS OF CATION EXCHANGE CAPACITY TO SOIL FRACTIONS IN SEVEN SURFACE SOILS FROM PANAMA AND THE APPLICATION OF A CATION EXCHANGE FACTOR AS A WEATHERING INDEX

A STUDY WAS CONDUCTED TO RELATE THE CATION EXCHANGE CAPACITY OF 7 SURFACE SOILS FROM PANAMA TO THE VARIOUS SOIL FRACTIONS AND TO THE MINERALOGICAL COMPOSITION ASCERTAINED BY WET CHEMICAL METHODS AND X-RAY DIFFRACTION ANALYSIS. THE CATION EXCHANGE CAPACITY (CEC) AND MINERALOGY OF TROPICAL SOILS IS VARIABLE DUE TO THE DIVERSITY AND ECOSYSTEMS AND GREAT SOIL GROUPS ENCOUNTERED. IN RECENT VOLCANIC SOILS THE CEC TENDS TO BE RELATIVELY HIGH, WHILE IN THE OLDER VOLCANIC SOIL THE CEC TENDS TO BE RELATIVELY LOW. IN YOUNG ALLUVIAL SOILS THE CEC IS RELATIVELY HIGH, IN PLANOSOL THE CEC WAS RELATIVELY HIGH. IN SOME SOILS THE CEC COULD NOT BE FULLY ACCOUNTED FOR BY EITHER ALLOPHANE, CLAY MINERALS OR ORGANIC MATTER. IT IS BELIEVED THAT THIS IS DUE TO HIGHER CEC VALUES OBTAINED AT PH 7.0 RATHER THAN AT THE NATIVE SOIL PH AND TO OTHER ANALYTICAL ERRORS SUCH AS RETENTION OF ACETATE WHEN USING THE AMMONIUM ACETATE METHOD. THE RELATIVELY HIGH CONTRIBUTION WAS NOTED OF THE SILT FRACTION TO THE SOIL CATION EXCHANGE PROPERTIES, PARTICULARLY IN THE ALLUVIAL AND LATERITIC SOILS. A WEATHERING INDEX OR CATION EXCHANGE FACTOR WAS OBTAINED BY DIVIDING THE CLAY ACTIVITY BY THE PERCENT CLAY. THIS INDEX WAS APPLIED TO THE SOIL DATA TO PLACE THE SOILS IN A CERTAIN WEATHERING SEQUENCE.

  • Supplemental Notes:
    • Vol 109, No 5, PP 324-331, 1 FIG, 6 TAB, 19 REF
  • Authors:
    • Martini, J A
  • Publication Date: 1970-5

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Filing Info

  • Accession Number: 00237889
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 3 1970 12:00AM