A regular pattern in the relative areas of soil profile classes and possible applications in reconnaissance soil survey

Abstract

The relative areas of soil profile classes are found to show an unexpected regularity in various landscapes (where relative area is defined as the proportion of the total soil-covered area of a region which is occupied by a particular soil class). If i classes are ordered by their relative areas ( A 1, A 2, …, A i ) then a plot of the cumulative relative area CA n (the sum of relative areas for classes 1 to n in the sequence) against A n , may be approximated by a straight line. The slope of this line, which must pass through the origin, may be estimated from the relative areas of the commoner soil classes which may be identified in a reconnaissance soil survey of a region. From the slope it is then possible to predict the total number of soil classes in the region whose relative areas exceed some threshold. This procedure is offered as a technique to aid reconnaissance soil survey, particularly where a surveyor must derive a soil classification from a set of samples obtained by a random sampling procedure. An estimate of the number of soil classes which occur may help in the planning of additional purposive sampling to produce a satisfactory classification on which to base a map legend.