ABSTRACT
During soil formation large spaces are formed by physical and biological action, and so soils are even more porous than would be expected from a random packing of particles. Soil porosity is part of the property known as soil structure which includes the arrangement of particles into aggregates and the size, shape and distribution of pores both within and between the aggregates. The formation of soil structure thus requires both physical rearrangement of particles and the stabilization of the new arrangement. Stability is particularly associated with organic materials linking mineral particles together and with the clay minerals and sesquioxides. Knowledge of the factors controlling structural stability and the processes involved in damaging soil structure has led to significant changes in soil management in temperate climatic regions of the world. Soils with low organic matter contents which include many cultivated soils and are often termed mineral soils.
