Two simple indexes for distributions of soil components among size classes

Abstract The destruction of soil aggregate structure in the field can lead to increased rates of erosion and decreased soil fertility. Methods developed to quantify aggregate stability have evolved around the application of disruptive forces that are comparable with those observed in the field, such as erosion, slaking and tillage. The indexes proposed here quantitatively summarize the degree of disruption with respect to a reference level based on the maximum disruption level possible for a given soil. The calculation takes into account the particle size distribution associated with the maximum level of disruption (texture) of the soil sample. The aggregation index can be calculated from the disruption index by difference. These indexes allow comparisons to be made between soil samples taken from several locations that have different initial aggregate distributions and textures. The characterization of an aggregate distribution in a single number (index) allows for easier statistical comparison of results from a wide range of studies. The indexes could potentially be used to characterize the change in distribution of organic matter after disruption associated with a given aggregate size distribution.