Describing and interpreting the macrostructure of mineral soils - a preliminary report

Abstract

A revised approach is presented for the description and interpretation of soil macrostructure. Structure is defined so as to include the size, shape and arrangement of voids as well as aggregates. Limits are suggested of the minimum sizes of voids and peds that can be described reliably in the field. The importance is emphasized of a decision on the purpose before soil macrostructure is described and two levels of detail of description are presented. The simple system of macrostructure description outlined is considered to be adequate for many applied purposes. The detailed system presented is required for thorough characterization of benchmark pedons and for some applied purposes. The concept is supported that descriptions of macrostructure should be used in estimating soil properties important to the purpose at hand. Guidelines are proposed for estimating properties such as saturated hydraulic conductivity, available water, and air capacity from information on structure and other soil properties readily determined in the field. Measurements of soil properties are required periodically to check estimates based upon guidelines and to improve the guidelines if necessary. The usefulness of soil macrostructure description in assessing effects of land use on soil physical condition is documented.