The Soil: The Soil Matrix
Even the most uniform soil presents a heterogeneous environment or matrix to a plant's roots.
This matrix must be explored sufficiently by the roots to provide the plant with adequate support, water and nutrients.
The relationship between a growing root and the soil is a complex one and is influenced by the texture, structure and chemical composition of the soil as well as a host of soil fauna and microorganisms.
This photo shows the underside of the root mass of a recently fallen mountain ash tree (the small photo in the top left puts it in perspective). The exposed roots are extremely dense and occupy most of the available soil space between the abundant gravel and small rocks. Fine roots are prolific in the topsoil.