Attempts to Explain the Variability in the Cation-Exchange Capacity of Soils in Terms of Particle Size and Organic-Matter Levels

Abstract

A study is herein reported where attempts to explain the variability in the cation exchange capacity of Lajas Valley soils in terms of other soil properties were made. The independent variables considered were percentage of particles smaller than 0.002 mm., percentage of organic matter, and the summation of the percentage of particles ranging from 0.05 to 0.002 mm. and smaller than 0.002 mm. The correlation coefficients obtained were 0.44, 0.47 and 0.46 for each respective attempt. Only 19 percent of the variability in cation exchange capacity could be explained on the basis of the percentage of particles smaller than 0.002 mm. in size. Another simple correlation where the percentage of particles between 0.05 mm. and 0.002 mm. was added to the percentage of particles smaller than 0.002 failed to explain satisfactorily any significant additional variability. A multiple correlation including the percentage of organic matter, in addition to the percentage of particles smaller than 0.002 mm. also failed to explain any significant additional variability. This failure is analyzed in view of the different nature of montmorillonitic clays that predominate in Lajas Valley soils.