In sandy or compacted soils the ability of mycorrhizal fungi to promote soil structure may be more important than the seeking out of nutrients. Soils in natural settings are full of beneficial soil organisms including mycorrhizal fungi. Research indicates, however, many common practices can degrade the mycorrhiza-forming potential of soil. Tillage, fertilization, removal of topsoil, erosion, site preparation, road and home construction, fumigation, invasion of non native plants, and leaving soils bare are some of the activities that can reduce or eliminate these beneficial soil fungi. In many man-made landscapes we have reduced or eliminated the soil organisms necessary for plants to function without high levels of maintenance.
Nursery grown plants available to landscape contractors are often deficient in mycorrhizae.
Plants raised in most nurseries receive intensive care and feeding. The artificial conditions, high levels of water and nutrients and sterile soils at the nursery keep certain soil born diseases to a minimum and produce vast quantities of plants for sale. Unfortunately, the high levels of water and nutrients and the lack of mycorrhizae discourage the the plant to produce the extensive root system it will need for successful transplantation. The result are plants poorly adapted to the eventual outplanted condition that must be weaned from intensive care systems and begin to fend for themselves. Application of mycorrhizal inoculum during transplanting can encourage plant establishment and set the plant on track to feed for itself.