Intrinsic Mesoscopic Spatial Variability in Macroscopically Uniform Soils

A soil judged to be uniform when viewed at a macroscopic scale may be a highly diversified population of grains and pores when viewed at a microscopic scale. If so, at intermediate scales, it will exhibit an intrinsic mesoscopic spatial variability (IMSV) that cannot be eliminated by thorough mixing and fastidious packing. For a given soil, data from a stepwise mechanical analysis or a stepwise drying curve can be conventionally construed as counts of grains or pores assigned to specific size classes. For any set of parcels of equal volume, it is postulated that counts for the j th size class will be normally distributed about the mean. The smaller the parcels, the greater the expected amplitude of normalized deviations. A description of IMSV uses the raw data and a table of probabilities of suggest replies to questions about how small parcels of macroscopically uniform soil must be if there is to be some predetermined probability that the data for the j th size‐class in any one parcel will deviate to a predetermined degree from the mean for that class. In effect, IMSV suggests lower limits on parcel‐sizes that could be called representative elementary volumes once a tolerable probability has been chosen for specified deviations from the mean for all parcels.