6. Bio-fertility is created in small amounts, and is localized in the immediate root zone (rhizosphere) where it is needed.
Like air and water, the soil is a precious resource, but it is not an unchanging resource. On the contrary, the quality of the soil in any one location can change dramatically in a relatively short time. Our urban environments are a good example of this. Soils in natural undisturbed forest areas generally contain robust and diverse populations of mycorrhizal fungi. In urban areas however activities such as site development, tilling , topsoil removal, grading, digging, and soil compaction destroy many of these beneficial fungi.