The soil is a living environment, full of organisms that influence plant growth and health. These organisms include visible inhabitants like earthworms, as well as a multitude of invisible, microscopic inhabitants like bacteria and fungi. Plants—through their growing roots—are also part of this living environment. Many of the interactions among these inhabitants occur through biochemical signalling, particularly in the rhizosphere.
Soil microbes and the biochemical compounds they make play a major role in nutrient release and nutrient use efficiency.